1987 420SEL. How to Jerry rig the air conditioning?
 

My 290,000 mile 420SEL is a few weeks away from being traded in. I live in South Florida where we use a/c nearly every day of the year. Yesterday my a/c started blowing warm air. After checking the fuses, swapping the fuse-box relays and checking the high and low pressure switches, I tested the compressor clutch by wiring a hot lead directly, at which point the compressor operated properly. My quick fix was to run a 2 foot wire from the hot pin of the leftparking lightharness plug to the compressor lead. That way I can turn on the parking lights to operate the compressor.

Here's the question. Where can I easily access a power source that is switched by turning on the a/c blower switch? I was thinking there might be an a/c relay somewhere, but I don't know where. Any advice from a professional or shade-tree mechanic would be greatly appreciated. By the way, I don't know if this is a related clue, but the aux radiator fan is now coming on with the ignition key even when the car is totally cold. That never happened before yesterday. Thanks, guys!