CrazyHawaiian

I just recently started having problems with the A/C Fan and/or Blower Motor in one of my cars. I've done some searching and I have a good idea about where to start troubleshooting, but I wanted to make a post with all the info and see if I'm doing anything wrong.

So the scenario, 91/92 Camaro with the L98/700R4 and 100K+ miles. The HVAC Fans have never worked right since I had the car, no biggie to me I planned to fix it at a later date. With the A/C or Vent on the fans would always blow on low speed regardless of where the Fan Speed dial was at. Just so happens a few days ago the Fan Speed dial was on high and I turned the A/C off after using it and for the first time ever since I've owned the car the fans turned on at the high speed. This isn't really a problem but this is where the problems started. First thing, the fans won't turn off now, even if the A/C or Vent is at off. They still change speed via the dial, they just cant be turned off. Thought it was no big deal, take a look at it on the weekend when I have time. The next day I'm driving the car with the A/C off and Fan Speed dial on low (I can hear it spinning slowly) and I stop at a stoplight and out of nowhere smoke starts coming out from under the console/radio and I smell burning. I flipped out and popped the hood in traffic, got out my fire extinguisher and could not find a fire. I wanted to take a look but because I'm busy with work I didnt have a chance. Now today I'm driving to work again and it happens again, out of nowhere smoke billowing through the console out of the vents and that burning smell. And again, no fire. So I decided I really need to do something before an actual fire starts.

Here is what I've found as possible causes from searching (thank you Tim Burgess, Vader, RB83L69)

1. Check the blower high speed relay near the blower motor under the hood.
2. Check the red wire fusable link / connector from the blower high speed relay to the battery
3. Check the fusible link between the blower high speed relay and the starter
4. Check the ground wire connection for the fan motor.
5. Check the vaccum lines to the black canister on the firewall next to the wiper motor. (vacuum for heater and a/c controls)
6. Check all fuses in the fuse box and in the "convenience center"

I realize I probably need a new blower motor, the current one is probably drawing too much current which is what caused these problems. I also plan to replace all the fusable links with actual in line fuses (12 AWG). I would like to measure the voltage drop across the blower high speed relay contacts while the blower is on high, but I'm afraid to turn it on again in case something starts on fire.

So now here's my questions: I pulled the "HTR-AC" fuse in the fuse box. I put the A/C off and Fan Speed dial on low. With the fuse removed the entire system is off right? I want to do as much as I can to prevent a fire while I troubleshoot this (might be over the course of a few days). Anything else you guys can recommend to prevent any possible fires? Also, how do I know if these relays are bad? Junkyard replacement a bad idea? Thanks for any help you guys might be able to provide. Really appreciate it.

CEP89

Get a wiring diagram and check to see if a previous owner did some creative rewiring. If it's still stock you should be OK with the fuse pulled. My guess would be the fan switch on the dash. I would not recomend junkyard relays, they get exposed to too much water. You can test a relay with a 12 v power supply hooked to the coil terminals and a meter on the switched terminals. There is a terminal diagram on the relay.

CrazyHawaiian

Thanks for the help. I found a good wiring diagram on the Autozone website. There is extra wiring that was added by the previous owners, took me a while to identify all the extra stuff and mark it off (I'll eventually pull it out when I have more time). I've made sure all the extra stuff is disconnected from the system and taped off (temp fix). I was able to go over all the wiring in the engine bay and I dont see anything obviously wrong as far as melted or burnt pieces. I'm probably going to have to remove the blower motor to really check everything out. The blower motor probably needs to be replaced anyway so no biggie. Does anyone know if the fusable links are closer to the blower motor or the starter/battery? Thanks again!!

CEP89

The fusible link should be close to the battery. Looks like you are on the right track to solve your problem. Good luck!

JRobling

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