Air Conditioning

[StuartGuy]

I have an 86 coupe. The AC works but in a strange way. I'd like to fix it If I can find the problem. What hapens is the AC runs nice and cold and when the interior reaches the set temp the unit starts to blow really hot air to regulate the temp. Not exactly what you want with sun on your face and head on a 95 degree day. Also, the unit temp settings jump from 16 degrees celsius to 19 degrees celsius (no 17 or 18) but then climbs properly through 20, 21, 22 etc. Any comments or suggestions?

 

[Robertwav1]

I'm not familiar with the controls for the AC on an 86. I would guess more discreet devices used to control tmperature rather then the electronics today. Sounds like a bad potentiometer or variable thermistor that has some shorted areas especially the way it's acting. I'm sure others will give you more information on what exactly to check. Hopefuly you can replace an inexpensive part to solve it.

 

[HPG]

Sound like the compressor runs for awhile, gets cool , then shuts off. This would be the reason for the hot air. Just a thought, did you check the condenser to be sure it's not clogged. Compressor will cycle off due to high head pressure if the condenser is dirty.

 

[StuartGuy]

Where do I find the condensor. Sorry, not very familiar with AC systems.

 

[c4cruiser]

I'm assuming from this that you have the C68 Electronic Climate Control system and not the standard lever system. You'll find the condensor in front of the radiator. When you look up under the car behind the front plate, that is what you see. Look for any of the fins damaged or bent so that the flow of air may be cut off. You can also have a lot of debris between the back of the A/C condensor and the front of the radiator.

It sound like the control unit is going bad or that the wire harnessconnector is not making good contact with the circuit board. Not seeing just some readout values sounds like the unit is bad. The inside air temp should not rise so fast as to bypass numbers especially when you see all the others. The sensor that determines the need for cooling/heating may also be bad. On my 87, its behind a small grille located in the rear hatch window trim panel above the seats.

You can remove the A/C control unit from the dash and pull the wire connector. Use a new rubber eraser on a lead pencil and clean the contacts on the circuit board. If that doesn't help, you may need a new control unit.

 

[vette-dude]

I think a low freon condition will cause the compressor to cycle. Have you had the freon level checked? You have to take it to a shop for this unless you know someone with the gages. Just a thought.

Randy

 

[StuartGuy]

The freon was good last year when this problem was going on. I'll check the things you suggested c4cruiser. Thanks guys.

 

[The Car Whisperer]

I would definitely check between the condensor and radiator for debris. I just replaced my condensor and found the space between the radiator and the condenser filled up one third of the way with all kinds of small debris. Leaves, papers etc. Definitely not good for the AC or the cooling system. You should check it even if you get the AC working, if you clean it out it will work even better!