Heater Fan Problems

[Sparky-Watts]

Ok, as I stated in my other post about the cig lighter, I HATE electrical problems!!!

Last winter, my heater fan started acting funny. Sometimes it wouldn't run unless I banged on the dash. Then it would only run if I reached up under the dash and wiggled what I thought were wires around. The other morning in the rain, I wanted the defrost to clear the windshield and it wouldn't run, so I tried wiggling the old wires. Nothing. Got to looking under the dash, and what I thought were wires I was wiggling appear to be vacuum hoses. One is black and runs through the firewall, the other is green and disappears behind and above the heater controls. I was thinking it was a short in a wire somewhere, but now I don't know. Why would a vacuum line cause it to act that way? All the dampers and everything else work fine, just the fan motor won't run.

Anybody got any ideas? Any pics of what the backside should look like? Are these vacuum lines really part of the problem or just coincidence?

Please help, winter is coming and the way I procrastinate, I'll probably be working on this at 5 below zero!!

 

[LRwrnglr]

I had simular problems and found out that theres a plug under the battery tray on the firewall. mine was unplugged, so i plugged it back in and it works. dont know if that will help, as for the vaccum hoses, i have no clue.

LR

 

[Sparky-Watts]

Very interesting! I just looked (best I could without removing the battery and tray) and I don't see any wire going to the blower motor. Of course the engine is still mighty hot because I just got home from work, plus it's 95 degrees in the shade and 120 in the garage. I'll pull the battery and tray tomorrow morning while it's still (relatively) cool out and have a look-see. I've got a Haynes manual which shows a drawing of the heater motor and an exploded view of the heating system, but no actual picture of the motor or any wires that go to it.....don't know why I bought a Haynes.....they suck!!!!

Thanks for the tip, LR, I hope it works out. I'm guessing my son knocked the wire loose when he was installing the power cable for my amp on my stereo....it runs right up next to the blower motor to the battery.

 

[XJNick]

Hi,

The vacuum lines are not directly part of the problem because AFAIK vacuum is only used to control the vent dampers (and in no way controls the fan motor).

You should find the wiring from the fan motor and trace it back to the source (if possible) to check for any loose/corroded connections, torn/frayed insulation, etc... The wiring for the fan motor will likely be fairly large, like 12AWG or 10AWG wiring, so it should be pretty easy to locate.

Also, be sure to pull and inspect the blower motor resistor block (it is usually mounted in the side of the air duct, near the fan itself). The resistor block is likely faulty if the fan works fine in the "high" speed setting but not in the lower speed settings.

-Nick :!:

 

[Sparky-Watts]

Hi,

The vacuum lines are not directly part of the problem because AFAIK vacuum is only used to control the vent dampers (and in no way controls the fan motor).

You should find the wiring from the fan motor and trace it back to the source (if possible) to check for any loose/corroded connections, torn/frayed insulation, etc... The wiring for the fan motor will likely be fairly large, like 12AWG or 10AWG wiring, so it should be pretty easy to locate.

I did trace the vacuum line I was wiggling, and it coincidentally runs right past the motor on the engine side of the firewall.....guessing it was against the wire and by wiggling it, it was causing the connection at the wire to be intermittent.

The Haynes Toilet Paper I have shows a wiring diagram with the heater wires at 14AWG. Going out in a while before it hits 105 again today to pull the battery to check it out. Gotta get a load of coffee on board first.

 

[pushead]

What color is the wire that connects to the heater fan under the battery tray? I accidently cut it out with a bunch of usless wires and need to put it back. I have to fittings with the same design.

 

[wrangler4meplease]

Ok, as I stated in my other post about the cig lighter, I HATE electrical problems!!!

Last winter, my heater fan started acting funny. Sometimes it wouldn't run unless I banged on the dash. Then it would only run if I reached up under the dash and wiggled what I thought were wires around. The other morning in the rain, I wanted the defrost to clear the windshield and it wouldn't run, so I tried wiggling the old wires. Nothing. Got to looking under the dash, and what I thought were wires I was wiggling appear to be vacuum hoses. One is black and runs through the firewall, the other is green and disappears behind and above the heater controls. I was thinking it was a short in a wire somewhere, but now I don't know. Why would a vacuum line cause it to act that way? All the dampers and everything else work fine, just the fan motor won't run.

Anybody got any ideas? Any pics of what the backside should look like? Are these vacuum lines really part of the problem or just coincidence?

Please help, winter is coming and the way I procrastinate, I'll probably be working on this at 5 below zero!!

mine has to be right on either "defrost" or "heater", one human hair to the right or left & it won't work