Hello everyone,

I have a 1987 300 SDL. I used to have intermittent heat and AC in this car so I parked it awhile till I had time to work on it. Now I have nothing from the CCU at all. If I have just the left plug plugged in, then I have full blower thru defrost no matter what buttons I press. I popped the cap on the right plug and removed the pins one at a time. When R 12 is pulled out I get the full blower and defrost, but none of the other functions work. I have been unable to track down any information on the CCU pin layouts. Hopefully, someone has a suggestion or can send me in the right direction.

Thanks,
MGS