Okay, I already DID the heater motor upgrade, so we'll get that out of the way.

Now, as I recall, this thing did work great...for a while. Blew like a hurricane, would almost drive you out with the heat. But now it doesn't. Harldy blows at all, the air that does come out is warm, but it doesn't seem to move air with the ferocity that it did before. Also, I seem to recall that after I installed it, the heater motor operated at three speeds, now it only operates at one, full tilt, which isn't very full tilt.

WTH did I do wrong? Or what happened that I had no control over?

I'm on my way out to the garage now to try to figure it out. I'd appreciate any help...winter is rearing its ugly head, and the Jeep is chilllllllyyyyy.

Boots

Sounds like the resister blew. That is what controls the fan speed.

OK what modification did you do? Will it work with the YJ heater fan? Thanks

Just in case :flipoff2: :D

No idea about a YJ but on a CJ the resister controls the fan speed.

Check the resister, as stated above.

Did you replace the wire that goes to the motor or use the Jeep one? Now replace the wire with a much thicker one, the same Chevy that you can get the motor from has the correct size wire.

I replaced my 77 CJ with a 84 heater system, every last part. The differance between the wire's is HUGE!

Oh Yeah, found on the Search option, References:
Terry Howe's Jeep Heater Blower Motor Upgrade in a CJ.
www.jeeptech.com/body/heater.html
Chris Waterman write-up on the Chevy heater motor swap in a YJ.
www.bc4x4.com/chrisw/projects/heatermotor/hmotor.asp

I have since discovered that the fan IS in fact running in all three speeds, i just couldn't hear it over the usual noise of the Jeep. At least, if it didn't work before, it does now. I've no ascertained that the problems consist of the Jeep just not heating up enough. Must be time for a new thermostat.

I also need to do some work to the ductwork where the air comes out, long ago the little divider and re-directioner broke off. Perhaps a good time to upgrade to the 4WD hardware version.

Damn Jeep...foolish of me to think I could get heat out of it. :)

As kind of an aside, does anyone know what the little bundle of wires that runs to the far right side of the heater box does? Its a bundle of three wires that plugs like a switch on the heater box. I thought this had something to do with the heater motor, but I can unplug it and it doesn't do anything to the fan. :confused:

Oh well. I'll figure it out eventually.

Boots

That 3 wire bundle plugs into the fan speed control resistor sitting just inside the duct.
Leave it alone. Or replace the resistor if you can't get 3 speeds.

Originally posted by Jaffer
That 3 wire bundle plugs into the fan speed control resistor sitting just inside the duct.
Leave it alone. Or replace the resistor if you can't get 3 speeds.

On my heating system I removed the upper portion of the duct work and sealed off my cowl vent. No more water leaks and I use the air that is already in the Jeep (suposedly warmer than drawing in outside cold air....I live in Canada) for heating. This was in an old article from JP. Besides the cowl looks nice and smooth now.

I had to relocate the fan speed control resistor.

I now only have 2 speeds on my fan...medium and high...not a big deal but should I replace the reisitor to get the 3 speeds or could I have done something to it when I made the mods.

The resistor has two coils.
The motor circuit is switch (via your dash fan switch) to go through both coils for low speed, through just one coil for medium speed and by passing the coils for a full 12v high speed.
so if you are only gettng 2 speeds the problem is either in the resistor (which can be easily checked with an Ohm meter) or the problem is the switch which is also easily replaced.
The only other problem would be a broken wire between the switch and the resistor.

If you seal up the air inlet grill on the outside of the tub, where does it draw in the air now?

Tim

Anybody with a FULL SIZE Jeep out there that can help me with the heater in my '76 Cherokee:question:

The core is beginning to seep into the cabin and the fan flat out SUX!!

Originally posted by Tmartin
If you seal up the air inlet grill on the outside of the tub, where does it draw in the air now?

Tim

The air now comes from inside the Jeep. Apparently it will get you more heat as you are using warmer air rather than cold outside air.

Besides it's a Jeep and there is plenty of fresh air coming in from outside.

Jaffer
Thanks, I'll check it out.