A/C hot and cold...
07-07-2008, 04:52 PM
#1
Track Day
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A/C hot and cold...
First post here so please bear with me. I have an '87 Turbo. A/c blows cold up to a month ago. I started hearing a click....seemed to come from the glove box area and after the click the A/C would blow hot. I hear the click again and it's back to cold. Needless to say in Las Vegas when it's 112 I hate the hot part. Any suggestions?
Thanks in advance!
John
'87 951 Turbo
'94 928 GTS
Thanks in advance!
John
'87 951 Turbo
'94 928 GTS
07-08-2008, 11:15 AM
#4
Hey Man
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There's a solenoid for the HVAC behind the glove box. When it fails it clicks and cycles the air box doors both hot and cold. Easy fix. A failed plastic clip on the drivers side console will blow hot all the time and won't cycle.
Originally Posted by Techno Duck
...Mike, the clicking is the automatic climate control solenoids doing there thing. On my '87 it use to go on the fritz for a couple days and then stop. It was worse when it was cold out and the interior was trying to warm up. Drove me nuts. You may notice it goes away if you turn the temp **** to max in the opposite direction it is in now. Im not sure how to fix the problem with them.
For the fans only working on 4, take out the resistor block that is under the plastic firewall cowl. The contacts on these get corroded over time and will cause the fans to only work on the highest setting (no resistance through block). I soaked mine in white vinegar for an hour or two and hit the contacts with fine sandpaper. Before i cleaned it, on very hot days it would always cause problems.
For the fans only working on 4, take out the resistor block that is under the plastic firewall cowl. The contacts on these get corroded over time and will cause the fans to only work on the highest setting (no resistance through block). I soaked mine in white vinegar for an hour or two and hit the contacts with fine sandpaper. Before i cleaned it, on very hot days it would always cause problems.
07-08-2008, 07:27 PM
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Track Day
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Thanks for the replies...and thanks for the welcome. I got on my back and looked up under the dash and didn't see anything that would be a mixing flap. Now that could be because I must be blind if it's there ( a possibility) or the system is a different year model than you are describing. I will admit ignorance when it comes to 944's. I bought this one because it is in such good shape and I drive it to not put miles on my 928 (422rwh 403rwt) I'll look again now that I have a better idea and ...are you talking about the expansion valve for the other possibility?
Thank you,
john
Thank you,
john
07-08-2008, 07:31 PM
#6
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Ahhh...I didn't see Steve's reply on the first read....You are describing exactly the problem with regards to the clicking and location. How does one fix that? I would guess pull the glove box and replace the solenoid
07-08-2008, 08:00 PM
#7
Hey Man
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I posted a photo of the solenoids on your other 944 thread. Pull the glovebox, drive the car, and have someone put their fingers on both solenoids and wait until it starts clicking. It isn't scientific but it works.
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07-10-2008, 11:19 AM
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ac/heat valves
My two cents worth...I bet it's bad solder joints in your climate control unit. Hence the "bump". It's probably allowing the heater coolant valve to open producing heated air. An easy way to check...after driving car to normal temperature, park it and feel the two coolant/heater pipes between the glove box and console if both are hot your heat is or has been on. A quick fix is to bypass the vacuum solenoid that controls the heater valve so it's sending vacuum to it constantly keeping the valve closed. The valve itself may be bad, vacuum test it. You were probably getting cool air, then hit a bump and start getting cold air. I just fixed this same problem by replacing my CCU. The old CCU solder joints were floating in flux. The clicking noise I believe to be the two vacuum solenoid valves by the pipes. The "plastic pieces" only control flaps to control air flow direction, foot, dash vents, defrost, & recirculate. Not cool/hot. It also could be a million other things. Good luck.
