Heater fan only works on LOW (1 Viewer)

[BJSnooper]

Hey,

Its not quite a real time help question but its darn near it. Its a balmy -25C (the warmest day this week) with overnight lows of -33 to -35C. I won't even get into the windchill.

Anyways, I've been somewhat having fun driving the 40 until the heater quit. I obviously had both the front and rear heaters on high. I can't pin point the exact time it went as I made a quick errand and shut the truck off briefly then once it was restarted I noticed the front fan quit while on high setting. It could have gone off while I was driving but I have a sneaking suspicion that it went off when I restarted it.

So, the rear heater works on high and low. Front heater only works on low and the control knob is in the proper "low" speed position. I pull the know out to high and the heater just turns off. Its so bloody cold out I have been hesitant to be jiggling wires around and it is not all that pleasant to have gloves off and digging around.

Thoughts? I may pull the control knob out and take a quick look at it and clean it up a little. Beyond that, I'm stumped.

Thanks for the tips

 

[BANDICOOTII]

My first guess would be the switch. Usually Hi speed is full voltage to the fan motor all other speeds run thru a resistor in the switch circuit to change resistance to the fan motor. Since you have low speed seems there is voltage running thru the resistor circuit to the motor which leads me to believe that circuit is intact. The high speed selector or contact in the switch may be bad which does not run thru the resistor. I don't think there are selectable speed windings in the motor per sea so I would concentrate on the switch first...Usually when the motor burns out its gone, no speeds...My .02 hope it helps a little...

 

[roma042987]

Ha ha I'm having the same problem with mine seems like it blows really hard for low setting though. And it hasn't been too cold here so I haven't messed with it. Blower didn't work at all on mine when I got it so not sure how hard hi should blow. I can take my switch apart tom and i'll post back if it fixes mine.

 

[Fast Eddy]

Here's what you do. Grab a jacket, a bottle of liquor and a credit card. Drink just enough to stay warm. Drive south 1500 miles. You'll be fine.

Seriously, though, pull the switch and take it inside to work on it. Get some dielectric grease from the nearest auto parts. You'll find it has one set of contacts for the front heater that are bad for the high position setting and another set that are good for the rear heater. (That thing kicks ass on high too, doesn't it?) Tear into it, clean, regrease the contacts, take a few pics for posterity, put it back and stay warm.

But seriously, wouldn't it be nice to live in Phoenix or Tuscon during the winter?

 

[splib]

Here's what you do. Grab a jacket, a bottle of liquor and a credit card. Drink just enough to stay warm. Drive south 1500 miles. You'll be fine.

Seriously, though, pull the switch and take it inside to work on it. Get some dielectric grease from the nearest auto parts. You'll find it has one set of contacts for the front heater that are bad for the high position setting and another set that are good for the rear heater. (That thing kicks ass on high too, doesn't it?) Tear into it, clean, regrease the contacts, take a few pics for posterity, put it back and stay warm.

But seriously, wouldn't it be nice to live in Phoenix or Tuscon during the winter?

Ha! At those temps, I'd have the bottle empty before I left the driveway!

 

[BJSnooper]

But seriously, wouldn't it be nice to live in Phoenix or Tuscon during the winter?

You have no idea! man, I was just outside checking a few things out and I had to come back in after 5 min just to warm up.

I think you're right, something is funky with the pull switch. I'll pull it apart and muck with it inside. Thanks for the tips.

 

[chevurai]

Before pulling the switch check at the fan housing where the low speed resistor is located ( the Frankenstein looking coil thet is about 1/2"x3" long). There should be a second wire, high speed, and a bullit connector. Check for power at this location and that the connection is good, and no broken wires.
Got nothin' there then check the switch.

 

[Tim71FJ40]

Once the switch is out, assuming you have to go that route, ohm it out before tearing apart. I believe you should read a short between power pin and low speed pin with switch in low position and same for high speed. This means power at the power pin will be successfully routed in hi and lo in the respective switch position. Pull the layers of the onion back one at a time when troubleshooting electrical before jumping into the guts of something.

Test as much as possible with truck intact, then start isolating things one at a time. Let us know if you get it fixed and what the issue was.

 

[Living in the Past]

Why not just put a jumper across the resistor at the blower and let it run on high speed when the switch is on low? Then worry about fixing it when it warms up.

 

[bikersmurf]

Why not just put a jumper across the resistor at the blower and let it run on high speed when the switch is on low? Then worry about fixing it when it warms up.

X2
Unless you've got a heated garage... That's what I'd be doing.

 

[UZJ40]

But seriously, wouldn't it be nice to live in Phoenix or Tuscon during the winter?

I'm only 27 and I've already turned into a snowbird...

 

[Living in the Past]

But seriously, wouldn't it be nice to live in Phoenix or Tuscon during the winter?

I'll take Phoenix year round. After see what most cruiser look like by the time there forty years old I stay right here in AZ. Helps to have second home in the northern part of state. There right now. 6:00 PM and it's already below low freezing. Coming from Wisconsin this is almost tee shirt weather.

 

[Tim71FJ40]

It's going to be 80 degrees in Fort Worth today. I don't even know what a heater is!

 

[FJfarty]

I'm having the same issue.. Works in first postion but not second!

 

[fj404life]

1st position is high iirc.