Heater (electrical) Questions ???

[Sicboy]

I bought my '66 at the beginning of this summer, and up until now I had never turned on my heater fan...mainly due to the fan control lever being broken off. Recently, the temps have dipped into the teens, so I decided to try and turn on the fan by sticking a little screwdriver in the slot where the lever would be and move the broken lever into the on position. It worked...the fan operated in both low and high mode.

Here's my problem...while the fan was on high, I noticed that the generator light was dimly lit. When I turned the ignition key off, the engine didn't immediately shut off and ran a few seconds longer while the key was out. Then I realized the key was hot. So, I reached up behind the dash and felt the back of the ignition switch and it was burning hot. I let the switch cool down, then tried the fan in the low position and drove a few miles. The gen light was no longer on, but the ignition was still hot, but not as hot as when the fan was on high. Can anyone tell me what the h*ll is going on?

[markeb01]

I'm not an electrical professional, but it sounds like the heater motor is drawing more amps than the electrical system can support. When the motor is set to either of the two lower speeds, it is running through a resistor in the back of the inside ducting. The two legs of the resistor cause the motor to run at the two different reduced speeds. In high fan mode, the power goes straight to the motor.

Hopefully one of the electrical experts here can provide a technical answer, but I would be looking for anything that increases circuit resistance, like a bad feed wire, bad ground, or the motor has an internal breakdown in the windings. I know it's getting cold out, but I wouldn't be running the heater at all until this is resolved, as it could easily start an uncontrollable electrical fire.

I had the same problem with an aftermarket a/c-heater system. The motor itself got so hot it actually started generating smoke in the cab. After the 2nd replacement motor did the same thing, I pulled it and replaced the motor with one from a Fiero, and never had another problem.

[62gmc910]

Originally Posted by Sicboy

I bought my '66 at the beginning of this summer, and up until now I had never turned on my heater fan...mainly due to the fan control lever being broken off. Recently, the temps have dipped into the teens, so I decided to try and turn on the fan by sticking a little screwdriver in the slot where the lever would be and move the broken lever into the on position. It worked...the fan operated in both low and high mode.

Here's my problem...while the fan was on high, I noticed that the generator light was dimly lit. When I turned the ignition key off, the engine didn't immediately shut off and ran a few seconds longer while the key was out. Then I realized the key was hot. So, I reached up behind the dash and felt the back of the ignition switch and it was burning hot. I let the switch cool down, then tried the fan in the low position and drove a few miles. The gen light was no longer on, but the ignition was still hot, but not as hot as when the fan was on high. Can anyone tell me what the h*ll is going on?

some one probably put a hi output fan from a newwer truck in It pulls to much load for the system thus the imbalance and light on condition , if you need full fan it should be run thru a relay system

[Sicboy]

So, I replaced the blower motor and it did not fix the problem. Then I replaced the butt connectors on the ignition switch. Still having the same issue...the ignition terminal on the ignition switch gets burning hot when heater fan is on. I just ordered a new ignition switch from Brothers, hoping that it's the problem.

[62gmc910]

Originally Posted by Sicboy

So, I replaced the blower motor and it did not fix the problem. Then I replaced the butt connectors on the ignition switch. Still having the same issue...the ignition terminal on the ignition switch gets burning hot when heater fan is on. I just ordered a new ignition switch from Brothers, hoping that it's the problem.

It won't you need to run a relay : take a 20 amp in line fuse (plug in type prefferably with cover ) hook to the power wire at the horn relay or at the battery which ever is better get a bosch style hi beam relay and a plug tomorow I will find one and draw a diagram and get part numbers for now just use the second highest fan setting