The AC in my daughters 03 Corolla abruptly quit last week. I isolated the problem to the AC clutch relay. I can make the system work by jumping the contacts in the relay socket. I also get 175 ohms across the relay coil which is telling me that the coil is burned out. The 175 ohms is from the parallel resistor that protects the coil from an induced voltage when power is removed from the coil.
The B+ terminals, coil and contacts are always hot. The coil is energized by finding ground through the cars ECM. It appears that all other circuits are working properly. We went to O’Riellys and tested a new relay, it did not fix the problem. I confirmed all my troubleshooting and told my daughter to go to the Toyota dealer and get a relay from them. Turns out they want $105 for this relay, ouch, and they will not let her try one first. They claim that the car could be blowing the relay, which I say is bogus.
Anyway, is there something I could be overlooking. We are going to try O’Riellys again, but this time I’m taking my ohm meter and test cables with me to check the relay first.