I'm at a loss here. My heat or AC isn't working. Checked the fuses behind the glove box, they're fine. I've heard most accounts say that if the resistor is fried it usually only works with one speed. Mine isn't at all. The resistor was also working with my multimeter 1.2 ohms I think. It did have a little corrosion but nothing major. My relay is clicking when I flip the switch so I don't see it being a problem. The weird part is my AC button doesn't light up when pushed in either. Not sure if it's just coincidence in that regard. That's what is kind of throwing me off. Otherwise I would just assume the motor itself is fried. I'm in the process of testing that but that one screw in the back is a PITA to get out. I'm also disassembling the dash to see if I can see anything wrong with the switch itself. Again though, the relay was clicking so I would think it wouldn't be that.

Is there anything else it could be? Something I'm missing somewhere.

 

Quite simple to unplug the blower motor and test with a 12vdc power source .

Then if it is good you don`t need to pull it out .

Have you tested the switch making sure that is working like it should

Does not hurt to change the resistor while your working on it

It might help to know just what your working on

 

Sorry about that, 93 Toyota pickup 4x4, standard 22re.

 

Wow! The rest of us are using a $6 multimeter to diagnose electrical problems, when all we really needed to do was listen for a click!

Do it the easy way. Pull out the heater relay, and test it. Then test that it has 12v on the correct terminals in the socket. Check for continuity OUT of the socket. http://web.archive.org/web/201102052.../2aircondi.pdf

Your relay could "click" but not close the terminals. You're not going to hear the electrons. If the relay isn't passing 12v, the A/C switch is not going to light.

 

That's for the input, electrical stuff isn't my strong suit. I just read that it "most likely" isn't the relay if it clicks. Turns out, it probably is. I tested the voltage coming out of the switch to where the relay plugs in and it was getting voltage so I figure the switches themselves are fine. I pulled apart the relay and the coil was fine but there was some burnt-ish looking corrosion on the top leading me to believe it was probably something there causing an issue. Ended up ordering a new relay since they aren't too expensive. I also checked the wire connected directly to the blower motor and there was nothing coming out of it. No damage to any wires that I could see. I'd assume that's the least likely problem. So probably and hopefully is the relay since it's an easy fix. At least I'm getting a good knowledge of how all this works!