Hello to all. I followed the advice of Herb Goltz and others while trying to troubleshoot my A/C not working condition last night. I tried jumpering the connections accross the pressure switch on the receiver drier and didn't have any luck. If I'm not mistaken this tells me that this switch is not getting power and so my problem is located upstream.

My next approach was to remove my MCC Control Unit and check the connections on the circuit board. I got everything out but I'm not sure what I should look for specifically. I'm going to try to have someone who knows what they're doing look at it later but maybe someone who's done this can give me some pointers.

Thanks
Don Tibbetts

I did this repair a couple of years ago. In about the middle of the circuit board there is a black plastic box, probably the largest component there. I think it is the main relay which switches the compressor clutch current, but maybe not. On the solder trace side of the board, you may find barely visible cracks in the solder holding this part's pins to the copper traces. I found my cracks easily by taking off my glasses and holding the thing to my nose, but I am very near-sighted. I you are not, try a magnifying glass.

Once you find suspicious solder, you need to "reflow" the metal with a soldering iron until it is smoothe and shiny, possibly adding a but more solder while you are at it. The small electronics soldering iron may not be powerful enough, but be careful you don't over-do it if you use the big gun-shaped tool.

Be open-minded about where on the board to look - I think these solder failures might be partly due to temperature extremes (cold winters?), not just high current, so could occur anywhere.

Good luck.

Brian
Thanks for the detailed info. A friend of mine and I looked at it this morning through a magnifying glass and found a solder that looked suspect. It was one of the ones that you were talking about. We hit it with the solder pencil. I can no longer see the crack that I did. Is there any way to test this without putting it back in the car?

Again, thanks alot Brian.