I have a 1987 420 SEL and I'm having a problem with the air conditioning. The problem is that the A.C. is intermittent. It will work on my drive in to the office, and then it won't work an hour later, then it will work at lunch. There is no rhyme or reason that I can discover.

It's hot here in Denver and I'd love to get any thoughts. The coolant is full and the belt is tight. Any other thoughts? Thank you.

 

Need more info. Does the fan quit or the air blow warm?

 

Sounds odd. You should see if the compressor is engaged when it is failing. If not, check the level and if ok, my first culprit would likely be the KLIMA relay located up on the firewall next to the engine control unit and fuel pump relay. The fuel pump relay and Klima relay are identical looking almost. The fuel relay will say something like "8 zyl 5500 rpm" and The Klima should say Klima. A/C pushbuttons are known to go bad wuite often too. There is a solder joint inside which seperates and fails. Difficult diagnosis without seeing it.

 

The fan works, but it blows warm air. I drove four times today...three times the A.C. worked, and once it only blew hot air. Thanks for your thoughts.