Hello,

My heater won't run.

It used to only run on HIGH, I bought a new Resistor and installed it. All speeds work well when the blower runs.

I tested blower with 12V battery, works fine.

My heat went out on me completely (so I put in resistor) and it didn't work.
I then checked blower, runs fine.

I was driving to work with no heat this morning and the heater engaged, saving my bitter morning.

It worked well at lunchtime, then I shut the car off, started it up again and no heat once again.

It can't be a relay/fuse issue because it worked just today....any ideas?

Actual interior switch itself?
Loose/broken wire somewhere?

Year and model? That info helps alot, even if you think they're all the same because some models are more complex (dual zones, etc).

I would check the blower speed control switch. The contacts can become oxidized and worn over time, especially if the resistor went bad and heated it up some. Also check the connectors for overheating. Finally, check the fuse for the blower and the holder for signs of overheating.

Welcome to AF!

Even though you checked the blower motor and you said it worked when connected to the battery it still maybe the blower motor. I had that happen to my mothers car last year and I jumped the blower motor directly to the battery and it worked so I cleaned up both connectors for the 2 wires going to the blower motor and I thought that I had it all fixed until 2 days later when the A/C stopped again in her car. I went to check the blower motor again connecting it to the battery and to my suprise the blower motor didn't work at all this time. I went and replace the B/M in her car and never had any more problems. I currently have this same problem in my 95 Park Ave, the B/M works 90% of the time so I'm waiting for it to stop so I can check it against the battery also. Can't do it if it is still working. Thats the bad part of electrical stuff, its so hard to test for it when it still works part of the time and we need to wait for it to fail 100% to find it.

Terry