Out of the blue, my heater fan stopped working. The light in the speedometer comes on, and I checked the connections to the switch behind the dash, and the fuses as well. All good there. My radiator fans still turn on when they're supposed to as well. This was of course a week after I got my overheating issue taken care of and everything on the car working wonderfully. Any advice before I have to take the whole dash apart to replace the actual heater fan unit?
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the fan speed ak power supply is managed via a resistor which sits in series with the motor.
0) As the indicator light goes on it appears the fuse is ok #10
1) disconnect cable from resistor (R) at the unit and feed 12 V directly to motor...see if it runs
(that should be possible per monkey style laying down on the pass. side)
2) if it runs check the resistor, it is a heavy Watt type I think with resistant wire on a ceramic body. It might be rotted or broken etc.
3) if not broken the switch might be the issue, as are old. Need to remove the kick board on pass side for access, well 3 cable comming /going there end up as 2 at the resistor BK & R, so you can check there. do not recap the switch internals but the indicator sits on a different Terminal on the swich W/BK thin cable.
(look at the elctrical diagrams page 40 & 11)
Matthias
Thanks for all this. I'll bust out the manual and see if this all makes sense. I really wish I knew more about electrical in cars in general -- my brain hurts when I look at wiring diagrams -- but this sounds like a great opportunity for me to learn. Appreciate it.
On the passenger end of the motor/blower assy is a hole that you can stick a finger inside of and give the squirrel cage a spin. sometimes that will make her go again, which is also proof that you need a new blower motor as the brushes are failing. The new ones use taps in the winding to control blower speed so you'll need to modify some wiring. That big resistor will no longer be used.
Riley, know that DeTomaso/Ford did many running changes to the Pantera's wiring during the short production run '71-74. There are at least three different factory schematics, and a supplement for the '80s-'90s cars where Ford was not involved. What most owners do is to get a copy of a schematic published as close to the build-date of the car as possible, then mark it up to exactly match your car, as variations are found the hard way.
The changes can be devices added, wire colors switched and functions changed. Some schematics are in the POCA Archives and vendors sell 24" x 36" laminated prints for garage use. One is folded in the back of original Owners Manuals but not always in reprints. The TSBs (Tech Service Bulletins- also in the Archives) are invaluable in describing in print the many running changes.
You will also need a GOOD VOM (volt/ohm-meter) and patience. As a last resort, there are a few shops & individuals that specialize in sorting out Pantera wiring. Some wear robes and pointy hats with moons and stars....
add to Bosswrench.....do not go the route per my picture..I had every thing out, validated all wires & colors against Lee Farrell & Bill Taylor docu. Did severall mods and replaced def >100 y cable...took me all winter month.. is mod 4907 from prod date 10 1972
(only 50% of it)
- on white table dash part and left trunk part
- in the back front goes to the engine comp
- in the back rear goes to the front
Ok, good to know. I didn’t get a chance to mess with it today, will try tomorrow. Thanks all.
Depending on the physical size of your hands, dexterity and strength, it IS possible to remove and replace the heater fan assembly without pulling the dash. The motor is clamped down with a split housing and 2 (maybe 3?) small hex-head bolts. I didn't believe it was possible until a member with really large hands insisted that he'd done it. So I tried it- and did manage to get the fan out entirely by touch while laying on my back! Then a day or two later I put it back- accidentally reversed- and had to do it all over again....
All 12v DC motors in these cars use brushes and those do wear. Given that there's only a very few things that can go wrong with fractional-horsepower DC motors, it's likely yours either needs brushes or lube in the bushings. IF you can R & R it. And if you get stuck, well- there are directions for partially pulling the dash and thus finishing the fan motor removal.
Well, this is great news. I did the dash removal 6 mo ago so really don’t want to do it again
The replacement heater fan units come with three wires plus an earth. They are pretty expensive for what they are from the usual Pantera dealers. I am sure they are just a standard unit that could be sourced elsewhere, but I have looked and nothing jumps out.
The originals only have two wires . So it looks like there is a third speed available on the replacement units . Any experience on how best to wire these up considering the original wiring ? Is it possible to use the third speed? or just choose one and have two?
Yeah, I remember when I was doing my dash, people said to replace the heater as well... of course at the time, I thought that was silly since mine was working perfectly AND like you said, they are not cheap, so I scoffed appropriately and carried on. Now of course, I wish I did! haha
I got my replacement from these guys. $42. They also had the squirrel cages pretty cheap too. Can't seem to find them now.
https://nostalgicac.com/contro...r-motor-12-volt.html
No factory looking three speed compatible switch is available, so you'll ultimately have to settle for two of the three speeds.
@larryw posted:No factory looking three speed compatible switch is available, so you'll ultimately have to settle for two of the three speeds.
The Pantera Electronics Console Switch Controller will work with the three speed fan motor and will let you use all three speeds. The controller also lets you pre-set the RPM you want for each of the three speeds. The lowest speed is activated when you turn on the A/C and the higher two speeds are controlled by the Fan switch. If Nostalgic no longer sells the appropriate fan motor, Pantera Electronics could probably tell you where to buy one.
If you purchase a three speed motor and a DC motor speed control unit from eBay, you can have fully variable fan speed through the use of a rotating potentiometer. wire the speed control to the high speed motor winding. I did this on 2511 years ago and it works just fine.
if you gut an original rocker switch you can mount the potentiometer in a manner that makes it almost invisible
replacing the heater indicator light with an LED bulb will allow that bulb to illuminate even at the lower speed voltage
Larry
So much great info guys, thanks. If I buy that replacement motor, it's just plug and play with the old one? I was hoping to tackle this last weekend, but I was busy selling my other car so hopefully this weekend.
Blower motor 4320 is a universal part. A quick search for BM4320 found them for sale on Amazon, of all places.
because it is a three speed motor it is not a plug and play replacement for the original single speed motor, that derived its two speeds through the use of the ceramic resistor
other than using my suggestion of a DC motor controller, there are other options out there on how to wire three speeds. Sorry but I could not find them with a quick search
Larry
OK, thanks. I'll try to do some more digging myself.
