Intermittent AC stopping
 

Twice in the last week, I have had the AC intermittently stop blowing cold on my 1988 Turbo S. Last weekend I did a 125-mile drive and stopped to put on the sunroof when it got too sunny and warm and the AC was working fine for the hour drive. I stopped for an errand and 20 min later the AC would not blow cold, but after stopping for fuel (10 min later) it was fine. Blower motor is not the issue and its not the broken heater control clips as I repaired those. So when the AC stops it continues to blow air, but not cold air.

Similar situation this morning, I drove to a C&C 75 miles from home and the AC was fine on the highway up, and I shut it off for the final 30 min of secondary roads as it was a nice day. Heading home the AC was fine for 40 min and then just stopped blowing cold.

My initial thought was the relay and I opened that up and cleaned the terminals and contacts, and also checked to see that it energized when I applied 12v across pins 85 and 86. I put it back and still no AC, and I confirmed visually that the compressor was not running.

30 min later I tried it again and it is blowing cold and the compressor is running.

I don't have the equipment to test AC pressures so wanted to see if anyone had any ideas. It's not a daily driver so I may have my mechanic check the refrigerant, but it seems odd that it stopped working and started running again - on two occasions.

Thanks for any ideas

My 1990 S2 does that exact thing. The AC really cranks then I get spoiled only to have it not work next time I get in the car. I live in Washington so what i really cant do with out the heater

Pressure too high or two low is the usual cause for this. If it has not been charged recently then you can bet it's too low. That or the AC button is breaking. They made it replaceable on the later CC units, after 1986 I think.

Could be a loose connection for the compressor clutch too. Time to get out the multimeter and verify every connection is clean and tight.

So I believe that I solved the problem with what seems to be a cheap fix. Replaced the relay and it seems to be working well.

As I mentioned above, I did test the old relay and it was clicking and energizing, and closing the circuit when I applied current. I hate to just replace parts, but in this case it was cheaper to try than to bring it into the shop for a diagnosis, so worth the gamble in my mind.

I guess the old relay just got tired. Will post an update if I find that this is not the solution as the original problem was intermittent.

Thanks all.

what relay number did you replace?

It is possible that with the current going through the relay coil, heat builds up and causes an open circuit in the coil windings...once it cools off, the open closes again and the circuit is restored.