So a few weeks ago I had my AC converted on my 1989 xj6 to the new freon system. A new dryer, receiver, and hoses were replaced. Since then the AC hs been working fine until today. On a 35 mile trip the AC worked great until the trip home. After 5 minutes on the road the ice cold AC got hot and wasn't blowing as hard. After another 10 minutes of driving the low coolant light came on followed by a click and the AC began working good as ever. Any ideas as to what the problem is?

 

Sounds like it could be a problem with the a/c relay? Maybe try cleaning up the socket/pins and see what happens?

Larry

 

When the conversion was done the compressor relay had to be replaced. Are there any other relays that relate to this area of the AC system?

 

I don't think so, at least, not on my later system (factory R134A)

In my understanding, if the a/c has enough gas and the pressure is above the low-pressure cut-off point, the relay switches the compressor on and off as needed to maintain the cabin at the set temperature.

Dirty contacts or a duff relay can prevent the relay from energizing which could give the symptoms you describe. There may be another issue of course, however, cleaning or replacing the relay is a quick and inexpensive way to eliminate the relay as the source of the problem.

Larry

 

I'm going to throw out a few other items to consider. Larry's suggestion is solid and should be investigated. I believe in a different post you mentioned the car has not been used on a regular basis, I think you referenced your grandparents or parents as having owned it prior.

You may be having issue with.....

AC control unit, most of the time the issue with the control unit is related to blower speed control not functioning on low and medium speed settings, however you do set the blend of cool and heated air with the control, so do not eliminate it completely at this time.

The climate control unit (within the dash area) has multitudes of solenoids, control flaps, vacuum hoses and two potentiometers which act in concert to control the environment, not to mention two or three temperature switches as well.

It sounds like, based on your narrative, some, or one, of these devices is behaving badly, especially based on the reference of the air being cooled, then hot, then back to cool.

Somewhere within this website is a publication I uploaded several years ago titled "Delanair MK IV Air Conditioning System". Find it. It is a comprehensive manual on the system and describes all functionality of components. And it has pictures....even better!

Good luck, let us know what happens.

 

Thanks for the suggestion. I drove it yesterday and all worked well so we will see next time it misbehaves.

 

Cole,

It's possible an electrical or electronic malfunction caused both the A/C problems and the low coolant level indication, but it's also possible your coolant really is borderline low, so if you haven't already, please do check it!

Cheers,

Don

 

I was wondering about these electronic gremlins. I did check the coolant and while it wasn't too low I did go ahead and top it off and drive it around the block. During that drive neither the AC, nor the coolant issue reappeared so we will see as I drive it more. Thanks for all the help Don.
Best
Cole

 

Just an update:
Earlier this week I was driving the car and after 10 minutes of ice cold AC the system just started blowing hot air. The word from the tech is that a compressor switch was bad and was cutting the compressor on and off. $200 later and I hope this resolves the issue.
Cole

 

Thanks for the update, Cole.

Please keep us informed.

Cheers,

Don