replacing blower fan resistor, other issue?

[Greg5OH]

So my fan only works on hi speed, and foot heater doesnt work (vent a little bit, but mainly window defrost). I heard it could also be the temp limit switch? Can i bypass it? and where is it?

 

[ah1988ford]

I id some a/c work on our van which may be diffrent from the truck. I havent heard of a temp limit switch before in car a/c before it would be news to me. I do no think there is anything that governs the blower motors speed except the blower motor resistor and the switch in the cab. I think your resistor probably needs to be replaced, they arent expensive. Idk whats up with the vent,defrost and foot heater prob. jm2c

 

[franklin2]

If you want to check/fix your resistor assembly, take a meter and in with the resistors a lot of them have a little silver cylinder looking thing in there also. This is the over temp fusible link, and once it activates, it's no good. See if it's open. They use them in coffee makers and such also, and radio shack used to sell them. I have also just wired around them, but I will leave that up to you. None of the older cars and trucks had that little thing, I don't know when they started using it.

 

[Bashby]

I thought that was a diode that had something to do with the motor acting as a generator after you turn it off and it is still spinning.

 

[The Warden]

So my fan only works on hi speed, and foot heater doesnt work (vent a little bit, but mainly window defrost). I heard it could also be the temp limit switch? Can i bypass it? and where is it?

I'm pretty sure these trucks don't have a temp limit switch...I've torn into a few bricknose trucks and have yet to see one.

If you mainly have window defrost, that's USUALLY a vacuum problem...the system's designed so that, when there's a failure, the flaps default to defrost...that's a DOT requirement IIRC. Last time I had a problem like that, it turned out to be a crack in the main vacuum feed line to the climate control; used a short piece of hose to cover it up and I was good to go

The blower resistor is easy to replace...however, it might be a symptom of a failing fan motor. I had a resistor go out, so I replaced it, only to have the new one fail in 6 months. Pulled the fan and found that the motor was having difficulty turning; I figure the higher amperage to get the fan going was what killed the resistors. Some WD-40 in the bearings, and I've okay so far...but, long-term, the fan motor needs to be replaced.

Hope that helps some...good luck

 

[Ruger_556]

Vacuum problem will cause flap problems

 

[riotwarrior]

Vacuum problem will cause flap problems

Or pressure...causes a flap problem at times too ..I can think of a few situations where that occurs