I have a 1997 Honda Accord LE, 4 cyl engine. The A/C is not working. I have checked the A/C charge and it is good, and I have checked that the compressor clutch can engage and it does. There seems to be a problem with the compressor relay. There is power going to two terminals and two terminals that are not powered. One of the non-powered terminals goes to the clutch (I assume that when the relay closes, then the clutch receives power). The other non-powered terminal is a red/blue wire that, according to my wiring diagram, goes to the engine/power train control module. Does this module control the A/C as well as the other things it is named for? When I ground this particular terminal, then the relay will close and I get power to the clutch. I hope this doesn't mean I have a bad computer module. Could a bad relay act this way?
That is the ground control for the relay. That is how the ECM turns the A/C on and off. The ECM has decided not to turn it on for one reason or another. It monitors switches and other thing to makes it's decision and it's not satisfied with something it monitors.
June, 9, 2011 AT 6:36 AM
Thank you. I figured it was a grounding source since the schematic showed no other ground for the circuit. After reading some other information on the topic, I came to the conclusion that I needed to check the A/C thermostat. After diagnosing that part, I found out that it was not functioning correctly and by shunting a bypass around that, the A/C kicked on. I'm glad that I had read further, otherwise I was about ready to replace the two relays located just behind the front bumper: the A/C compressor clutch relay and the condenser fan relay. Had I done that I would have still had the problem.
Thanks for your reply as it verified my thinking on the subject.
June, 9, 2011 AT 9:27 AM
Make sure you don't leave that thermostat bypassed because it will cause the system to freeze up and that will damage the compressor.