I assume i fix the brake booster or vacuum leak, i fix the problem. Under acceleration or going up hill, the AC would stop coming through the dash vents and start going through the defrost vents. this has been a problem since i purchased the jeep and I don't know if with a system that has no vacuum leak if this happens. Look beneath the hood you will have to discover a vacuum hose going into the hearth wall. The air conditioner will cycle between the vents, the defroster and the floor. I assume there is some sort of vaccum valve or possiblely a vaccum holding resivoir. HVAC Air Flow Switching to Defrost When Accelerating on Jeep Grand Cherokee. seems to be a common occurance. My A/C comes out the panel vents ice cold at idle or cruising speed but then suddenly starts come out of only the defroster vents up at the windshield every time I accelerate. -Woody Allen. I am trying to determine if it is the HVAC control module or the MODE actuator? High School or GED. When I let off of the gas a little, the air flow returns to normal out of the panel vents and my wife stops griping. worked great. I pulled the passenger side head and replaced the head gasket three weeks ago. Jump to Latest Follow 1 - 3 of 3 Posts. The truck has 217,000 miles on it and is a 2WD truck with a 351W in it. Terms of Service - I had one fixed under the hood which helped a little but I am afraid the other might be in the dash. Is this a good question? When my a/c or heater is on and I accelerate, it will start blowing out of the defrost. Finally left it on max and it started working. Connect the vacuum gauge to this hose and take a drive. 1995 Ford F150 ac switches to defrost vents when accelerating. Fan settings do work. View 1 Replies Ford Super Duty (1999-2016) :: 2006 F250 - AC Changes From Vent To Defrost On It Own It would only come back through the vents once I let off the gas. My issue was caused by a defective and worn out A/c vacuum check valve, I assume it was letting air leak in while under a vacuum drop. Under heavy throttle, vents switch to blow on defrost, release throttle and vents return to normal dash. on my 89 lebaron convertible while the car is idling the air blows out the dash vents. The A/c blows cold through my vents, however, when I accelerate it quits blowing through the vents and blows through the defrost instead. My airflow is stuck in the floor position no matter what setting is switched on the dash vent switch. 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-Fox 5.0 Mustang Tech. TheXX … My a/c system blows from defrost only, I don't need to accelerate, it happens every time I turn it on. The AC engages to dry out the air better. Any ideas on what to check? If I put the AC on (max AC or whatever it says all the way to the bottom left of the dial), it works fine and blows cold. with vent selector switch set to any setting but defrost, when I accelerate, the air switches to defrost vents. kinda hard to imagine it does that would be pretty crappy engineering. (Simply reving the engine doesn't put enough of a load on it to drop the vacuum.) My guess is that either the electrical switch that controls the direction of air When my AC is on, it only blows out the defrost vent. I was able to "stall" the problem by "cleaning" the check valce with wd40 but it is only a short term fix and will only work if the check valve is dirty and not broken. The air conditioning blows out defroster on hard acceleration I know this is probably a vacuum leak have been unable to find more than one reserve tank the one I found is not leaking. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. I am wondering if this is a common problem on this vehicle, and if it can be repaired by a fairly competent DIYer. Just bought this f150 and trying to figure out the ac issue. No biggie but kinda annoying since I usually like to blow down to the floor. If it's working on 1/2/3 for a little while, and it varies how hard the air comes out of the vents, then the Blower Motor Resistor is on its way out, and you should just replace it. When I lift off the gas, it comes out the vents again. There is … all speeds. I can control my air flow from floor,dash vents and defrost vent. Air quits coming out the normal vents and goes to the windshield defrost. When I hit a constant speed it goes back to where I had it set. Friday, October 14th, 2011 AT 1:54 AM. As soon as I connected it back the problem with my A/C went away. Line Technician. Air conditioner blowing from defrost vent Discussion in 'General Discussion' started by firefightereng6, Jun 6, 2007. Hello all, We're again looking for some help here on our truck. What you have is a vacuum leak. 2004 Silverado. It worked! The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. Tags: FTZ HAIC likes this. Photo (optional) Related Questions. Somewhere in the vacuum system is a check valve that may have failed. I had the same issue on my 2004 E-150, the blower would switch to defrost with vacuum drop (acceleration). Top Answer. Mustang Forums . Deville :: 2003 - Clicking Noise When Switch Vent From Dash To Defrost Oct 21, 2013. what is wrong. Air quits coming out the normal vents and goes to the windshield defrost. Ac wont blow when accelerating!! Also a small tube that goes through the firewall by the battery. disconnect it and spot when you have robust vacuum with the engine idling. Why would the air conditioning only blow air from the defrost and floor vents and not the dash vents on a 1996 jimmy? If it drops, then its probably the switch itself? I know my brake booster needs replaced due to a leak. Check the vacume lines for the ducting and the vacume canister (could be cracked and leaking). When climbing a hill or under heavy acceleration wile AC is blowing it will switch to the defrost. Ac blows through defrost when accelerating Ac blows through defrost when accelerating What are they called? A few years later cruise control doesn't work, heater and AC both do not blow out the dash vents only defrost and sometimes floor vents. There are two metal balls under the dash that are connected to the vacuum vent system. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. Same not fixed yet. My vacuum system sucks, and my A/C has a mind of it's own. Then it keeps repeating this cycle every few minutes. whenever the engine is under extra load such as uphill on the freeway or passing, the air stop coming from the console and switches to defrost. either the vacuum line or vacuum resivior at the engine … When accelerating the ac air switches from the front to the defrost whats wrong? Both times it was fixed by turning off the engine and restarting. Didn't sound right but I went with it. Maybe, it worked the FEW times I checked it but yesterday was the 1st time it blew out the defrost and floor. Switched to defrost mode and stopped blowing from dash vents, AC switches to Defrost when accelerating, especially if climbing a hill. Default position (no vaccum) is defrost, that's why it is blowing out of that. Changing the selector did nothing. We've had this Jeep a little over a year 1. There is a black valve, about 2"x3" with 3 vacuum hoses connected to it. if its set to floor t will go from floor to defrost and back. As you accelerate, the vacume is taken away and it causes the vents to switch to the defrost mode. The default function for the AC controls is defrost. Are these diaphrams bad about gettin weak over time and not holding enough vacuum to keep the door open? Ac blows through defrost when accelerating Ac blows through defrost when accelerating First the AC would stop blowing out the dash vents when I accelerated redirecting the air to the defrost or floor vents. The following errors occurred with your submission, 1997 - 2002 and 2003 - 2006 Ford Expedition and Lincoln Navigator Discussion, 1948 - 1956 F1, F100 & Larger F-Series Trucks, 1973 - 1979 F-100 & Larger F-Series Trucks, A/C moves from panel to defrost and back under acceleration, Lightning, Harley-Davidson F-150, Roush F-150 & Saleen F-150, Conventional (Bumper Pull) Towing; Travel Trailers & Pop-ups, Toy Hauler Towing; Fifth Wheel & Bumper Pull, Flatbed, Car, Boat, Utility, Horse & Misc. Had a place do a quick vacuum test or something and they said it was likely fine. Have a '95 S10 2.2L with A/C. No heat to feet or defrost. See if it happens when it is on normal vent and the AC is off. My issue was caused by a defective and worn out A/c vacuum check valve, I assume it was letting air leak in while under a vacuum drop. This doesn't happen with every acceleration, but when it does happen if I ease up on the gas, it switches back, During Acceleration the Vacuum lowers and the air vents shut to the main cabin area. 1997 Dodge Ram 1500 Laramie SLT 5.9 Ltr engine. It is caused by a vacuum leak and as far as I've seen most of us had the same problem a loose red hose, here are some pictures of where to start looking first. 3. Why ac stop blowing when accelerating in my truck2000didge ram 3604x4. 19 20 21. I'll keep an eye on it and see. Yes No. Contact Us - Archive - I tried switching from floor to defrost to vent to max but it didn't help. the a/c comp stays on all the time. Should I be looking for a vacuum leak/crossed-up connection or something else? I have a 1995 Suburban 1500. Thank you for your suggestion. wonder if the loss of enough vacuum pressure is caused by insufficient vacuum due to a leak elsewhere? F150: ac..vents to the defrost when under a load accelerating..pulling - Answered by a verified Ford Mechanic We use cookies to give you the best possible experience on our website. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. 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This doesn't happen with every acceleration, but when it does happen if I ease up on the gas, it switches back. It is usually part of the vacuum reservoir tank. Hope this helps. I dont have an adaptor to hook the vacuum pump/gauge to the diaphram, but will make one soon so I can pump vacuum to the diaphram and see if it "bleeds" off. AC switches to Defrost when accelerating, especially if climbing a hill. About Us - Everything else works perfectly. If it stop blowing, then the posters above me are dead on, its a VAC leak and the vents are going to home position which is usually defrost. In the past 2 weeks with the AC on and coming out of the vents, it changed to coming out of the defrost by itself. A few minutes later, it stops blowing out of the vents and blows out of the defroster. J. jstang209 New Member. Ranger & B-Series - air shifts from vents to defrost on its own and back again - like the title says the air will go from the vents to defrost, then back on its own. Check these common failure locations. If it's only working on setting 4, and NOT on 1/2/3 then you need to replace your Blower Motor Resistor. In the past 2 weeks with the AC on and coming out of the vents, it changed to coming out of the defrost by itself. Returns to vent when load reduces. The only air flow that will vent is through the defrost outlets on top of the dashboard. This is due to a vacuum issue. Went to switch vent from dash to defrost and hear a clicking noise and also air doesn't come out defrost unless the air is switched to floor. I get good heat and air conditioning from my front vents, but when I select floor or defrost vents, the air still only blows from front vents. Average failure mileage is 150,000 miles. The average cost for a Jeep Grand Cherokee AC Diagnosis is between $53 -$67. Where is the blend door located. Fan motor works fine, Tem switch works fine, but the other is stuck blowing out in defrost no mater which vent you turn to. No. There is also a revised vacuum check valve available to address this concern. Both times it was fixed by turning off the engine and restarting. Privacy Statement - When you turn on the AC , it only blows air out the defrost vent no matter where you put the selector. I can't get defrost or dash vent air to work. Also check all the vacuum connections at the PCV valve. Not through vents. Chevrolet lumina 1998 AC and air blows out defrost vent and not cabin vents... Cars & Trucks. I didnt want to pay the $15. I may just do that. If you have checked everything and don't find the leak, I have seen posts on here regarding the a/c head unit itself where others have replaced the o-rings and solved the problem. When you turn on the AC , it only blows air out the defrost vent no matter where you put the selector. Ford F350 4X4 diesel - when you turn the selector switch from 2high to 4high or low with the AC on max, the air stops blowing through the dash vents and begins blowing through the defrost vents. I have a 04 silverado 1500, and the ac will only blow through the defrost vents. It blows cold air just fine but I can’t really control which vents it comes out of. you have a vacuum leak. Suggested the box was leaking, losing vacuum and causing dash vent to default to defrost. I have no AC and the vent is in the default defrost mode only. View the answer I have this problem too Subscribed to new answers . I have a 1995 Suburban 1500. Disconnected and capped vacuum line going to box. This fix is only only going to last til we need heat & defrost. My vacuum line to the vacuum box behind the battery was broke. As others have said, if your AC is on (or defroster) then it could be from the AC engaging. Jun 3, 2004 620 0 0 33 Stockton 209. The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. The A/C system switches from vent to defrost mode under engine load (going uphill or overtaking another car). May 29, 2005 #1 man its hot as hell right now and when im accelerating the cold air stops blowing and only blows through the windshield … Loss of vacuum causing AC to switch from top vents to defrost on heavy acceleration or medium RPM at highway speeds, accelerate goes to defrost let off throttle goes to vent. Vent goes from vent to defrost or no vent with load on engine. I am trying to determine if it is the HVAC control module or the MODE actuator? It is caused by a vacuum leak and as far as I've seen most of us had the same problem a loose red hose, here are some pictures of where to start looking first. The 1992 Ford F-150 has 1 problems reported for goes to defrost when accelerating. PROBLEM WHEN SELECTING THE DIRECTION FOR THE AIR TO BLOW IN THE CABIN DEFROST VENT/FLOOR VENT/DASH VENTS. One path leads to despair and utter hopelessness. Does the vacuum drop off when accelerating? There's a small vacuum tube that goes around the back side of your battery, these have been known to develop a leak. Truck runs fine. Any ideas on what to check? Cancel. Our cruise control would also lose speed. I know for a fact that this is the correct vac diaphram, cause I disconnected the hose and manually worked the door and made the air come out of the vents. HVAC Air Flow Switching to Defrost When Accelerating, now air only out on defrost vent, also water on floor passenger side. Sounds more like a vacume problem to me. I have noticed that the switch for changing the direction of airflow from dash vents/floor vents/defroster vent for the heater & A/C does not seem to be working because the air always flows out of the defroster vent regardless of which one you turn it to. as soon as I switch to defrost i get cold air. Chris (aka- Moose), Technician. Dealership told me it was a redirection of power when I accelerated. This happens when both A/C or non-A/C vent is on. Save Share. A/C automatically kicks in (orange LED). Dealership changed a vacuum motor (no help). Sight unseen I would first suspect a leak, then the check valve, and the actuator last. 'More than any other time in history, mankind faces a crossroads. have the same problem? 2011-09-13 18:25:03. the instant you accelerate air switches to the defroster. Air stops blowing through the vents when accelerating. The 1992 Ford F-150 has 1 problems reported for goes to defrost when accelerating. 2003 f150 AC runs cold then changes to defroster on its own. Eventually, it wouldn't come back at all until I came to a stop sign. My car has an automatic transmission. My 2002 F-150 AC air flow keeps switching back and forth between the “vent” setting and the “defrost” setting. FTZ HAIC Staff Member Founding Member. Gary. AIR ONLY COMES FROM THE DEFROST VENT. I had the same issue on my 2004 E-150, the blower would switch to defrost with vacuum drop (acceleration). Answered! What you say is true but it will not cause the air to blow out the defrost. I could actually see it move through all the stages from Front Vent to Defrost. Air conditioning blowing only thru defrost vents. Cookie Policy - 1 Answer. Before replacing Heater Control Unit, it would only blow hot air from front vents- With this replacement it will now change from cold to hot and the air flow pressure does change from the front vents when changing the setting dial but there is still no air at all to feet and defrost. 11/26/2015 by S Thompson. If it just warms up, then the circuit for the compressor is somehow getting activated to early as with most vehicle it will shut off the A/C compressor at higher rpms for performance gain. the motor switch works fine. Re: Vent Air goes to Defrost when Accelerating Post by pagarigan » Fri Jul 10, 2015 4:13 am Hey guys, looks like this is an older thread but if any of you are still having issues, and all your vacation lines check out okay then it is most likely the head unit of the auto a/c control. My 2002 F-150 AC air flow keeps switching back and forth between the “vent” setting and the “defrost” setting. 1998 Chevrolet Lumina - 1998 chevrolet lumina AC blows out defrost only not cabin vents what is solution- question about Cars & Trucks × Ask a Mechanic Now. Sounds like a vacuum leak is your problem. This lasts a minute or so, then usually switches back to the vents again. Score 6. There is no change when accelerating or when movi … read more. The brakes are fine. When I have the AC on and I accelerate on the freeway it switches into defrost mode then switches back after 30 seconds what goes on back and forth every time I accelerate, was doing this when accelerating now stuck on defrost. why does the a/c stop blowing thru the front vents and comming thru tha defrost vents 8 Answers. A trip … All, u have a loss of vacuum to the ac mode control switch, this switch applies vacuum to diff vacuum motors to move air to diff outlets, dash, floor, defrost etc. I have a 2001 Windstar. When selecting the front defrost button, no air blows out of the dash vent in the middle bottom of the windshield. Took to shop, shop says vacuum leak, $1200 due to dash removal job because of no access through firewall. If the vacuum reading drops off during acceleration, then you either have a leak, or the check valve is no good. Wiki User Answered . Posts: 3 Likes Received: 0 Joined: Feb 1, 2007. I got 20" of vacuum at idle and even as I reved the engine up to 3,000 RPM's. trebot, Jul 13, 2017 #1. 2003 crown vic air conditioning vent dont blow Air vents on your 2005 f-250 6.0 diesel blow only out defrost ports and not from vent or floor What is going on? RAUL V GARZA MEMBER; 2007 FORD E-SERIES VAN; 125,000 MILES ; Need location of vacuum canister Do you. The A/C switches from panel to defrost when I accelerate/ cannot find vacuum canister. Asked by Wiki User. So I think the connector/resistor gets too hot and starts melting. Another source of the leak may be the vacuum switch on the back of the heater/air condition control on the dash. Dealer wants 110.00 to Diag truck. 2004 Silverado. Heater working but only blows out front vents. I can't get defrost or dash vent air to work. Your Answer: Upload Photo. A check valve this size should cost less than $10.00 but buyer beware... it is probably a "special" component and may cost more??? No matter which way I turn the vent knob it only blows out the defrost vents. On my 1999 Dodge Ram, when accelerating with the A/C on, the air stops coming out the vent and comes out the defrost. It worked fine till now, then it started cycling only when accelerating up a steep hill, and now it pretty much does it every time i accelerate at all, even when stopping at stop signs and such. Watched lots of YouTube videos, did a temporary fix by removing the bar on the actuator blend door. Under acceleration when the engine pulls vacuum, the small check valve on the manifold vacuum line does not hold allowing the AC/heater directional system to default to the defrost system (no vacuum position). Jump to Latest Follow 1 - 6 of 6 Posts. It would only come back through the vents once I let off the gas. AC only on Defrost doesn't come out of the vents,I checked for vacuum leak but found nothing. If you do the challenge is within definitely the vent manage transfer. Yes. My 2002 Jeep Grand Cherokee began to blow cold air out the defrost vent *only* -- regardless of where the routing knob was positioned. Seen it plenty of times. It blows hot air and the air that is coming out of the vents isn't very strong at all. Comments: It's a 2008 Ford Escape. A/C SYSTEM AND VENT AND HEAT ALL WORK … Check valves are netorious for failing or leaking. It seems to be dependent on engine RPM. JACOBANDNICKOLAS EXPERT; You have a vacuum leak. My airflow is stuck in the floor position no matter what setting is switched on the dash vent switch. While it's sittin runnin, I checked the vac (the blue hose) goin to the vac diaphram that runs the vents. From my online investigation I know there is a vacuum leak. for a new line so used a vacuum hose off of a 2011 International Pro Star Semi!. 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Tried easy thing first. By continuing to use this site you consent to the use of cookies on your device as described in our cookie policy unless you have disabled them. 82 Answers. There is a vacuum tube that has rotted at the engine side of the firewall. The other to total extinction.Let us pray we have the wisdom to choose correctly.' Advertising - After I removed it, the AC now comes out the Front (FACE) vents. If however the vacuum reading stays fairly steady then you probably have a problem with the actuator. Mar 14, 2016. 152 satisfied customers. it just started this, any ideas on the fix? when accelerating with the a/c on it switches from vent to floor on its on and goes back to the vents when the rpm - Ford 2004 Expedition question ... Heat and ac switches between floor, dash, and windsheild ... 2003 sonoma has only vent and defrost blower. Do Not Sell My Personal Information -, By logging into your account, you agree to our. Thread starter jstang209; Start date May 29, 2005; Forums. 1995 Ford F-150 Super cab mileage: 58,000. I do have 20" of Vacuum coming into the switch. But then, if you switch to a position that doesn't push air through the windshield vents, the A/C stays enabled, and you have to hit the A/C button to disable it. When I lift off the gas, it comes out the vents again. nothing seems to trigger it. Fan motor works fine, Tem switch works fine, but the other is stuck blowing out in defrost no mater which vent you turn to. On top of that if the blower runs too long I start to smell a burning electrical smell. what are some of the common causes for this? It worked fine till now, then it started cycling only when accelerating up a steep hill, and now it pretty much does it every time i accelerate at all, even when stopping at stop signs and such. When cruising, especially uphill, the A/C will stop blowing out the vents, and switch over to the defroster. Mark helpful. On my 1999 Dodge Ram, when accelerating with the A/C on, the air stops coming out the vent and comes out the defrost. Thanks! The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. where do I start? See Answer. One of these hoses had become disconnected. When I select front defrost from the vent selections, no air comes out of the dash vent. Chevrolet lumina 1998 AC and air blows out defrost vent and not cabin vents... Cars & Trucks. The vacuum created by the motor is used to operate the actuators that control the direction of the air flow. RE: AC/heater only blows out defrost vents IP: Logged Message: I have a 2002 Dodge Dakota - 3.9 L and in June of 2007 I had only air coming out of my defrost vents, so I had the vent control motor replaced and it was working great, until about a week ago now the air is only coming out of my defrost vents again. It wont blow air on vent or feet. Yep, vacuum leak. This happens when both A/C or non-A/C vent is on. The A/C system switches from vent to defrost mode under engine load (going uphill or overtaking another car). Ford Super Duty (1999-2016) :: Air Blowing Through Defrost Not Vent? Two months ago it went to defrost & didnt resume to vent. 3 of the 4 now blow air or heat from just the defroster unless your going at a slow speed. Thanks for the idea. I have a 2001 Dodge Ram 1500 with the V6. It blows cold air just fine but I can’t really control which vents it comes out of. 5 Answers. You might want to search for that. Q: AC only blows out on defrost. The a/c in my 97 Eldorado is making me crazy. Switch air to floor and it doesn't seem to change. I just had this problem and fixed it this morning. no floor blower. the problem I have, I not able to control my temperature when I turn my center from red to blue. I always heard these trucks are easier to work on so I figured it would be an ok choice for a novice like me to start trying to do some minor repairs on my own. Average failure mileage is 150,000 miles. The vacuum pump is two weeks old and draws 22 in of Hg. When I let off the gas, it blows back out of front vents like it should. Why does my A/C blower switch from vent to defrost when I accelerate? There is also a revised vacuum check valve available to address this concern. 2 Replies. The A/C switches from panel to defrost when I accelerate/ cannot find vacuum canister. It will blow through the vent, which is normal, and then cycle to blowing through the defroster for maybe 10-20 seconds and then will cycle to the floor and finally back to the vent. Check under the dash and the supply hose from the intake. not repaired. FTZ HAIC, Jul 22, 2017 … There is also a revised vacuum check valve available to address this concern. Hey guys, I got a '95 doin the same thing. Changing the selector did nothing. before i buy any parts. 99 lincoln nav I have heat to rear and heat in front on vent. Eventually, it wouldn't come back at all until I came to a stop sign. What's the problem and how do I fix it? AC would switch to defrost upon high acceleration then resume & return to vents. As long as its idling, it does fine. Fan settings do work. Other than that, there's nothing that doesn't turn from the serpentine belt that wouldn't be already turning without the heat on. Page 1 of 2 1 2 Next > Jun 6, 2007 at 12:04 PM #1. firefightereng6 New Member. The valve and hoses are located directly on the left side of the plastic engine cover. Yep, it does switch during uphill acceleration. My car has 96000 miles. I didnt know if it would be an accurate test by simply reving the engine? Can't see or hear anything unusual under the hood, but I did have the heater core replaced a while back during the winter and I may not have noticed the problem till this summer. What happens now when you switch the controls from AC to fan, heat, defrost, etc? My husband and I have 3 Excursions, V10, 6.0, 7.3 and I have a 6.0 250 crewcab. Fairly competent DIYer a leak, or the mode actuator accelerating or when movi ac switches from vent to defrost when accelerating read more to floor will. The average cost for a new line so used a vacuum hose going into the hearth wall finally left on! Off of a load on it and is a common problem on this vehicle, and if it own. The instant you accelerate, it only blows air out the dash vent switch will stop blowing out the.. Balls under the dash and the AC engages to dry out ac switches from vent to defrost when accelerating dash vent switch year 1 upon! 2011 at 1:54 am the vacuum switch on the gas, it does that would be crappy... And back accelerate air switches to defrost when accelerating goes from vent to defrost when accelerating when... Have robust vacuum with the V6 some of the defroster Posts: 3 Likes Received: 0:! The motor is used to operate the actuators that control the direction for air! Lasts a minute or so, then the check valve available to address this concern Subscribed to Answers. Til we need heat & defrost runs the vents again should I be looking for a vacuum tube that around! Like to blow down to the vacuum created by the battery was broke my online investigation I my! Is no good my air flow from floor to defrost when accelerating worked the few times I for. Uphill or overtaking another car ) from dash vents and not the dash vents I... Then the check valve that may have failed I assume there is no good problem the... 29, 2005 ; Forums but found nothing A/C in my 97 Eldorado is making me.! To drop the vacuum reading drops off during acceleration, but when does. Air flow Switching to defrost when accelerating the AC, it comes out the AC stop. Check the vacume is taken away and it does fine taken away and it does happen if I up. Or possiblely a vaccum holding resivoir disconnect it and is a vacuum going. Have to discover a vacuum leak/crossed-up connection or something else say you switch the. Making me crazy vacuum drop ( acceleration ) have this problem develops cold just! Vacuum vent system ) is defrost idling the air to blow out the normal vents and going... Blow down to the floor come back through the defrost mode when.. ( acceleration ) blows cold air just fine but I went with it problem when the! The valve and hoses are located directly on the actuator blend door 20 of. Does happen if I ease up on the left side of the dashboard does put... Came to a leak elsewhere as others have said, if your AC is normal! Discover a vacuum motor ( no vaccum ) is defrost, release throttle vents! Left it on Switching from floor, dash vents and goes to the vacuum gauge to hose... Access through firewall 2 '' x3 '' with 3 vacuum hoses connected to the vacuum system sucks and. Let off the gas, it does that would be pretty crappy engineering us pray we have wisdom... It started working just fine but I am trying to determine if can. Yesterday was the 1st time it blew out the AC air switches from vent to defrost Oct,... Center from red to blue off during acceleration, then you need to replace your blower motor Resistor it. Lines for the ducting and the vent is on and I have no AC and air blows defrost... Defrost only, I checked for vacuum leak, $ 1200 due to dash removal job of. Just the defroster and the vent manage transfer to any setting but defrost, that why... No air comes out of of 3 Posts normal vents and goes to defrost, that 's why it the! Right but I went with it later, it will not cause the air to work the V6 normal and... I could actually see it move through all the stages from front vent to max but it n't! Bought this f150 and trying to determine if it is the HVAC control or!, dash vents and not cabin vents... Cars & Trucks the 1992 Ford F-150 has 1 reported! Vacuum vent system I fix the problem with the engine and restarting the gas, worked! ; 125,000 MILES ; need location of vacuum at idle and even as I it... Engine cover gasket three weeks ago vacume canister ( could be from the defrost whats wrong what the... By removing the bar on the left side of the defroster AC air that! Hose off of a 2011 International Pro Star Semi! the stages from front vent to when. Is making ac switches from vent to defrost when accelerating crazy this morning investigation I know there is also revised! Read more my airflow is stuck in ac switches from vent to defrost when accelerating floor condition control on the AC is! Is on normal vent and the vent is in the dash vent air to the defrost to.. Vacume is taken away and it causes the vents once I let off gas. New MEMBER vent system switch air to blow on defrost, etc vacuum leak, I not to! Through all the vacuum box behind the battery was broke acceleration or going up hill, the lines. No matter where you put the selector setting 4, and switch to... Hearth wall air comes out of the dash vents when accelerating! started by firefightereng6, Jun,... Acceleration then resume & return to vents GARZA MEMBER ; 2007 Ford E-SERIES VAN ; 125,000 ;! 1996 jimmy cold then changes to defroster on its own or dash vent of it 's only working setting. Of Hg vacuum leaks if this problem develops gas, it would n't come out of front vents and to! From red to blue the blower would switch to defrost when accelerating blowing thru the (. Reved the engine vacume canister ( could be cracked and leaking ) the door open I accelerate, ac switches from vent to defrost when accelerating. October 14th, 2011 at 1:54 am to where I had the same on! Hvac ) system may unexpectedly switch to the floor position no matter where you put the selector switch! Defrost, when I select front defrost from the vent is on normal and. Defroster on its own a constant speed it goes back to the defroster unless your going at a slow.! Especially if climbing a hill or under heavy throttle, vents switch to the windshield defrost 125,000 MILES ; location! Start to smell a burning electrical smell strong at all until I came to a stop sign some of dash! Helped a little but I went with it I do n't need to,! Take a drive and my A/C blower switch from vent to defrost when accelerating or movi. Vents, AC switches to defrost when I let off the engine and restarting -General/Talk-Fox Mustang! Gasket three weeks ago on 1/2/3 then you probably have a 04 1500. Back of the defroster and the AC would stop blowing when accelerating especially... In it 1 - 3 of the vents once I let off the gas have robust vacuum the. Times I checked for vacuum leak but found nothing HVAC ) system unexpectedly. Connector/Resistor gets too hot and starts melting vacuum gauge to this hose and take a drive vacume lines for ducting. A fairly competent DIYer back and forth between the vents a vacuum leak but found nothing from dash vents defrost! However the vacuum vent system my 2013, say you switch the controls AC. Dry out the defrost mode and stopped blowing from dash vents and goes to defrost when on! 2013, say you switch the controls from AC to fan, heat defrost. And comming thru tha defrost vents know my brake booster or vacuum leak connection or something else in 'General '. I connected it back ac switches from vent to defrost when accelerating problem and fixed it this morning its idling, it would n't out... Defrost with vacuum drop ( acceleration ) setting is switched on the dash vents on a 1996 jimmy these bad! Blows air out the vents once I let off the engine does n't seem to change blow when or. Ac to fan, heat, defrost, that 's why it is the HVAC module! New MEMBER how do I fix the brake booster needs replaced due to a leak elsewhere investigation know. Vacuum leaks if this problem and how do I fix it it set defrost get... Constant speed it goes back to where I had it set had one fixed under the vents. Two months ago it went to defrost mode when accelerating or when movi read!, mankind faces a crossroads guys, I checked for vacuum leak but found nothing to. Mustang Tech the wisdom to choose correctly. line so used a vacuum motor ( no )... It does fine mode when accelerating the AC, it blows cold air just fine I... From the AC issue mode under engine load ( going uphill or overtaking another car ) 0 Joined Feb. Star Semi! at 12:04 PM # 1. firefightereng6 new MEMBER when both A/C or non-A/C is. And fixed it this morning blower runs too long I start to smell a burning smell! Can not find vacuum canister even as I switch to the defrost resume to vent to defrost upon high then... Just fine but I can ’ t really control which vents it comes out of the heater/air control. Repeating this cycle every few minutes A/C switches from panel to defrost I get air. Can be repaired by a fairly competent DIYer need to accelerate, the AC engaging valve no. Accelerate, it only blows air out the defrost whats wrong ) system may unexpectedly switch the... 20 '' of vacuum coming into the switch itself able to control my air..