I can’t thank all you guys and gals enough for saving me big bucks over the years with your helpful advice on minor car repairs. Now for my next question. The a/c and heater blower fan doesn’t always shut off when I shut down the engine with the key. It will shut off if I flip the blower fan speed position to off. I have located the blower relay in the power strip. Is this causing my problem?
Probably. Here’s the schematic. That white wire that drives the relay’s coil is attached to a fuse so that, when you turn the power off, the relay deactivates and the fan goes off. Since that isn’t happening, either that voltage isn’t going away when you turn the key or the relay’s contact is shorted. The former is unlikely, the latter is very likely. You can probably just measure across the contacts with a multimeter set to resistance and see whether it is shorted.
Or just replace the relay and see if it fixes it.
If replacing the relay doesn’t fix the trouble then check to see if the white wire going to the relay has voltage on it which would turn on the relay and the blower. The drawing doesn’t show where that wire ties to.
Agree with the others, this is almost certainly a relay sticking on. One caution. Best not to try to measure the resistance across the relay contacts with the relay installed, there is a power source which could damage the dvm in certain cases. If you do measure the relay’s contact resistance installed, at the minimum make sure the blower switch is set to “off” and best to pull that fuse too. Me, I’d just pull the relay and measure whether it was stuck in the on condition with my dvm’s resistance mode with the relay laying on the bench. That way you know there is no other circuitry affecting the measurement. If you are short on cash, or just want to do an experiment, something I’ve opened up relays and found what is causing them to stick. Sometimes all you need to do is file the contacts a bit to clean them up. Best of luck.