Issue: A/C Clutch turn on then off. Electrical Buzz in HVAC Controller. System has no leaks and is 134a/R12 Full.
Possible Fix: My Ac worked fine up until 30 days ago. I had my local AC guy check and narrowed the issue to the HVAC Controller. Since I remember seeing a write up on replacing the internal relay, I thought I would give this a go.
I ended up buying all the pieces needed but found out that my internal relay is different. I ended up cleaning all the contact points with Brake Cleaner on a Towel to remove what I saw was oily substance all over the Circuit Board and then using my Dremel with soft brush at low speed on contact points as well.
My internal relay has a plastic removable cover, so I removed it and used a manual soft bristle brush and lightly brushed the contact points. Then I made sure to blow it out to ensure no bristles were left in the relay itself. Closed the relay back up and put the lower cover back to test it.
I started the car up and low and behold, I got arctic cold air again. I made sure to move the nicely newly installed slider back and forth and "NO" more buzzing noise. Somehow just cleaning it up nicely did the trick.
The irreplaceable Relay
Clean these contacts really good, you'll see yours won't be this shiny
Clean these Fingers as well
The top round thing is what the black plastic piece pivots on. You can remove the circlip and the pivot comes out revealing the metal pressure fingers which I also cleaned up. I also bent them slightly down more so it got nice contact with the Board.
Clean these Contacts as well.
