gc_caddy Posted July 24, 2004 Report Share Posted July 24, 2004 It's HOT out there (~95) Had the A/C on max but then upon heavy acceleration, the blower cuts out totally. I'm assuming this is normal to give me the extra horsepower. But should the BLOWER also stop functioning during this time? I would think that the PCM needs only to cut off the compressor. The blower and A/C returns a few seconds after I let up on the accelerator. Any way to deactivate this A/C cutoff? Link to comment Share on other sites More sharing options...
gc_caddy Posted July 24, 2004 Author Report Share Posted July 24, 2004 Oh yeah, no codes were set. Link to comment Share on other sites More sharing options...
Ranger Posted July 24, 2004 Report Share Posted July 24, 2004 I think you have some sort of a problem there. The PCM only disables the compressor at WOT, not the blower. Link to comment Share on other sites More sharing options...
98Concours Posted July 25, 2004 Report Share Posted July 25, 2004 Sounds like a vacuum leak. Jeff Jeff 98 Concours 90 Seville 04 Corvette Link to comment Share on other sites More sharing options...
franey Posted July 25, 2004 Report Share Posted July 25, 2004 I agree with the other post , you probably have a vacum leak . Right behind your power stearing pump should be a vacume line with a small black and gray vacume check valve, the line coming off t. he check valve will run un to a plastic Y, one line will run into your fire wall , the other one will run down to your vacume tank under battery. IF any lines have a hole in them or the tank, or the check valve is not working properly, when you accelerate to get on freeway or speed up, the air will not come out of the vents and it fells like the air went off, when you level out the air comes back on. YOU have a vacume leak. Link to comment Share on other sites More sharing options...
Ranger Posted July 25, 2004 Report Share Posted July 25, 2004 What does vacuum have to do with an electric fan? Am I missing something here? Link to comment Share on other sites More sharing options...
98Concours Posted July 25, 2004 Report Share Posted July 25, 2004 my blower motor was doing the same thing, so I took it in. The dealer found a vacuum leak under the battery. It happened when my battery leaked acid and ate thru a hose. They replaced the hose and it works great. Don't know what vacuum has to do with it, but it does. Jeff Jeff 98 Concours 90 Seville 04 Corvette Link to comment Share on other sites More sharing options...
franey Posted July 25, 2004 Report Share Posted July 25, 2004 When the vacume goes off the main vacume valve it closes all of the valves and you have no air flow , not because of no fan, but because the air flow is stopped. Gives the appearance of NO FAN. Link to comment Share on other sites More sharing options...
Ranger Posted July 25, 2004 Report Share Posted July 25, 2004 Well ok, that makes some sense but gc caddy says the blower stops. Also, doesn't a loss of vacuum default to defrost position? Link to comment Share on other sites More sharing options...
franey Posted July 25, 2004 Report Share Posted July 25, 2004 From the time you lose vacume on acceleration to the time it returns , varies from 1 to 3 seconds, if you have never experienced the vacume probelm we described here , it lasts about as long as it takes to saY . WHAT THE -ELL, and it is back on. MINE never came out the defrost because it happened so fast that by the time it went off, the valve to defrost apparently never had time to close before the valve returning the air to your upper vents had kicked back in and it was blowing out them again. His may be the fan motor , but i think he should check for a vacume leak first . I am not aware of anything that would literally stop your fan motor on acceleration and then when you level out a few seconds later it kicks back in. I can not find anything in the shop manual , which would give this condition momentarily on acceleration. Link to comment Share on other sites More sharing options...
pos2nat Posted July 25, 2004 Report Share Posted July 25, 2004 I also have this problem, but the fan shutoff period is so short I ignore it. I will now check the vacuum lines. It normally happens when I go over 3000 rpm. Link to comment Share on other sites More sharing options...
gc_caddy Posted July 25, 2004 Author Report Share Posted July 25, 2004 Thanks for the suggestions regarding checking for the vacuum leak. That never occurred to me. It hasn't happened today when I took the car out for a test. I think it might only cut out when the outside temp is very hot (>>90deg). It doesn't normally get that hot here in Vancouver, BC. I'll check the vacuum lines to see if there is a problem. Thanks again. Link to comment Share on other sites More sharing options...
JasonA Posted July 25, 2004 Report Share Posted July 25, 2004 I'll put my nickel into the kitty as one having had the same experience. The blower motor would "turn off" when at heavy throttle. The culprit was a bad vacuum hose, which tended to close the air mix door, as described above. The total effect was the motor quit running...but in reality, the door was simply shut. A few hose solved the problem. Mine was a hose underneath the battery, and was fixed by a dealership while under previous ownership (mother). The problem has kind of returned, and has kind of been there for a while (sometimes it does it, sometimes not). I've been too lazy recently to crawl under there and find the pinhole leak. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
franey Posted July 26, 2004 Report Share Posted July 26, 2004 If the hoses appear to be ok , replace the tank, it is only 11.OO, mine had a minute seam crack, which did not allow the vacume pressure to build up for when the check valve closed. Once i replaced it works perfect. Link to comment Share on other sites More sharing options...
gc_caddy Posted July 26, 2004 Author Report Share Posted July 26, 2004 If the hoses appear to be ok , replace the tank, it is only 11.OO, mine had a minute seam crack, which did not allow the vacume pressure to build up for when the check valve closed. Once i replaced it works perfect. Thanks Franey, I found the vacuum hoses that you'd talked about. I just did a quick visual check tonight and they appear OK (I'll re-check them more carefully tommorow). I have also located the black plastic tank under the battery. Is there a good way to check the vacuum pressure? Do I need a gauge or pump of some sort, or do I just visually look for pinholes/cracks or a hissing sound? Link to comment Share on other sites More sharing options...
franey Posted July 26, 2004 Report Share Posted July 26, 2004 IF you do not have any vacume gages or vacume pumps , run your car for about 10 minutes with AC OFF, BRING RPM UP , to about 2500 , you do not nave to hold it here long about a minute will do ,or just driv e around the block acouple of times. when you get back , lay just under the fender where you see the tank , reach up and pull the rubber piece off the end of the tank. YOU should here a slight pop , when you remove it, this is the vacume pressure letting go . IF you do not here it then your system is not holding the vacume. The second time mine went out i just replaced the check valve 4.00, TANK 11.00, 2.50 hoses, and bought package of vacume T's , which had a vacume Y IN it for 3.50. It was the tank , with a small seam crack, I figured for 21.00, it was a small price to pay to lay this problem to rest once and for all. NOW no matter how hard i get down on it , the AC , does not go off the vents. Link to comment Share on other sites More sharing options...
gc_caddy Posted July 27, 2004 Author Report Share Posted July 27, 2004 Sounds great, Franey! Excellent tips. Thanks so much! Link to comment Share on other sites More sharing options...
rayntx Posted August 15, 2004 Report Share Posted August 15, 2004 checked all the e mails concerning the a/c cutting off.............I have a 96 sedan deville and the problem if any that I am having is that the a/c doesnt cut off but it blows out from the bottom vent when I accelerate going up an incline or hill, as soon as I decelerate air comes out of the vents..........replaced all vaccum hoses, valve and evac resovoir and still having the same symptons. Drivng on flat roads dont have any problems.................any suggestions anyone.....confused in Texas Link to comment Share on other sites More sharing options...
bigfoo Posted August 15, 2004 Report Share Posted August 15, 2004 What about holding the brake and punching the gas, does that cut it off too? Link to comment Share on other sites More sharing options...
Ranger Posted August 16, 2004 Report Share Posted August 16, 2004 Rayntx, That definately sounds like a vacuum problem. You must have missed something somwhere. Link to comment Share on other sites More sharing options...
franey Posted August 17, 2004 Report Share Posted August 17, 2004 You have a defective air door valve under the dash. I had the same problem when mine was under warranty , if i can find the old shop ticket i will post what they replaced. Link to comment Share on other sites More sharing options...
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