any help yet...

[bill5674]

Okay lets try again,,90 c68 a/c. will set a/c at any temp,say 65.will jump to 75 ,and blow hot air. have changed out the dash head unit know good. Changed out the vacuum control module .same thing .Changed all vacuum lines ...they needed it.also changed the check valve at the rear of motor. Also cleaned as many grounds as the factory manule shows....has n`t anyboby had something similar? thanks Bill

 

[XLR8]

Okay lets try again,,90 c68 a/c. will set a/c at any temp,say 65.will jump to 75 ,and blow hot air. have changed out the dash head unit know good. Changed out the vacuum control module .same thing .Changed all vacuum lines ...they needed it.also changed the check valve at the rear of motor. Also cleaned as many grounds as the factory manule shows....has n`t anyboby had something similar? thanks Bill

Hey Bill,

The one time I had trouble with my a/c blowing hot air in my former C4, changing the vacuum switch (is that the same as the vacuum control module?) fixed it. Sorry I can't help.

Good luck with it. I hope someone comes along soon that can offer some suggestions.

Jane Ann

 

[bossvette]

If you have what is known as a "blend system" the hot water is always flowing thru the heat/AC unit there is a flap valve which controls the air flow thru the system directing it thru either the Heat or cooling exchangers or a blend of both. Assuming that your cooling system is working properly the position of the flap valve could be your problem

 

[bill5674]

thanks guys but the postion of the door (flap) is controled by the vacuum module

 

[gmjunkie]

thanks guys but the postion of the door (flap) is controlled by the vacuum module

Yes!! Unless the Plastic Clip is broken and the servo rod that controls it has came off the Flap!!Years and High heat while setting the sun make them brittle and brake!!!!! Common problem!! And a Pain in the WahZoo!!

 

[bill5674]

thanks junk .....let me think about that one.it does blow cold ,door closed to heater core,then the temp control jumps to 75..hot air door is open.I think that would mean that is workimg.For some reason it`s getting a signal to change temp,don`t think thats it.I bought a used vacuum module...my dealer said it`s no longer available. Hey Jane Ann, were you able to get a new one ,and did you have the same trouble? ...my head still hurts from laying under the dash saturday.The real pain is i switched her over to 134 about a year ago and still holds a charge and blows cold,at least for what it is.almost ready to isolate the flap leave it open and hot wire the blower!!

 

[XLR8]

Hey Jane Ann, were you able to get a new one ,and did you have the same trouble?

Bill,

my mechanic called it a vacuum switch. It was ~2 or 3 inches long and located under the hood near the top of the engine and exhaust manifold. Not connected to those things of course - just in that general vacinity. I want to say he charged me about 10 bucks to replace it! He said that the part gets brittle being exposed to the intense heat from the engine. He replaced it with a new one, yes.

The problem started one morning on my way home from work. It was already 90 degrees out, and my A/C was blowing nothing but hot air straight out through the defrost vents on top of the dash. I may be mistaken in my memory of the situation, but it seems that I couldn't get it to cut off either.

I had to drive to the garage with the windows open and continually wiping the windshield to see because it was fogging up everything in this humid climate.

Sorry I can't offer more info than that. I looked for the receipt for the repair but I can't find it. All I was able to find was vacuum switch replacement on my excel spreadsheet. And he DID charge me $10.70...

Jane Ann

 

[bill5674]

thanks Jane Ann that would be the vacumm tee/check valve.although mine was also not holding vacuum , changed it ,still did not solve the problem.

 

[XLR8]

Sorry that didn't help. Good luck with it, Bill.

Jane Ann