[william]

The heater on my 75 RC (has A/C also) had the usual meltdown when I bought it. I just replaced the 3 speed switch with a known good used one, replaced much of the wiring, connectors etc. I did not replace the blower motor. It appears to have been replaced at some point as it looks to be aftermarket. The blower will run for a while, and the fuse gets progressively hotter (the higher the blower speed, the faster it gets hot.). After 10 minutes or so, pop goes the fuse. Does anyone know what might be causing this? What is the correct resistance reading for the fan motor? Could this have anything to do with that ballast on the heater box? There is one crimp connector at the blower, but it is very well crimped. Help! Thanks,
william

 

[Chump]

What size fuse are you using? 20 amp? The resistor(ballast) block should not be causing a problem. I dont know of any published resistence values for the blower motor. I would suspect bad bearings in the motor causing a high current draw, or other internal motor problems.

 

[william]

Hey Chump,
Yep, it's blowing 20's. I can't think of what else it would be other than the motor, but I wanted to check. Everything else I am 99% sure is in good order. I will pull the blower and try another one. They should call this place Chumpcharger Central. I will post a followup on what I figure out...
william

 

[Chump]

Could be a bad bearing. They tend to get egg shaped after years of the weight of the blower wheel and gravity pushing down on motor shaft.

 

[william]

Do you know what years interchange by any chance? Everywhere I have phoned for a '75 just laugh and say there is no such part. Were they the same in the 80's? Thanks again Chump...
william

 

[Guest]

Different part number William so probably not the same. Autozone carries one though, the part number is PM230 and the price is $58.99.

Chris

 

[Chump]

With A/C the factory part number should be 3620822 and this number can be used to cross over at most stores. Here's a list of other part numbers, I'm not sure who carries what brand in Canada. Gotta get the one for factory A/C as it has a provision for a cooling tube that attaches to it. If we can help any more let us know
NAPA BK 665-1337

BLOWER MOTOR
A1 CARDONE 41-56 [Blower Motor] Reman.; w/o AC
AC DELCO 15-8337 [Blower Motor-New]
AC DELCO 15-8860 [Motor, Blower] w/ Factory AC Or w/o AC
ACI 333818 [Blower Motor]
AUTO TEMP M3818 [Blower Motor-New] 1 Per Veh;
AUTOPRIDE PRIVATE LABELS 41-56 [Blower Motor] Reman.; w/o AC
AUTOSTAR PRIVATE LABELS 35555 [BM Motor - w/ AC] Deluxe Heater-Stamped-3773389, 390
AUTOSTAR PRIVATE LABELS 35555 [BM Motor - w/o AC] Deluxe Heater-Stamped-3773389, 390
AUTOSTAR PRIVATE LABELS 35555 [BM Motor - w/ AC] Std Heater; Stamped-3556601, 602
AUTOSTAR PRIVATE LABELS 35537 [BM Motor - w/o AC] Std Heater; Stamped-3556601, 602
BIG A 35555 [BM Motor - w/ AC] Deluxe Heater-Stamped-3773389, 390
BIG A 35555 [BM Motor - w/o AC] Deluxe Heater-Stamped-3773389, 390
BIG A 35555 [BM Motor - w/ AC] Std Heater; Stamped-3556601, 602
BIG A 35537 [BM Motor - w/o AC] Std Heater; Stamped-3556601, 602
NAPA/BALKAMP BK 6551337 [Blower Motor]
CARQUEST 208991 [Blower Motor-New]
CARQUEST 208991 [Blower Motor-New] 4X4
CAR CARE PARTS PM380 [Blower Motor] w/Frigiking A/C
CAR CARE PARTS PM537 [Blower Motor] OE# 3620822; (Includes w/Std. Heater Only, Mtr. Stamped 3556601 or 3556602); (Includes A/C)
CAR CARE PARTS PM324 [Blower Motor] w/Deluxe Heater Only; OE# 4094016; Mtr. Stamped 3773389 or 3773390
EVERCO M1836 [BM Motor - w/o AC] Std Heater; Stamped-3556601, 602
EVERCO M3818 [BM Motor - w/ AC] Std Heater; Stamped-3556601, 602
EVERCO M3818 [BM Motor - w/ AC] Deluxe Heater-Stamped-3773389, 390
EVERCO M3818 [BM Motor - w/o AC] Deluxe Heater-Stamped-3773389, 390
READY-AIRE 5230 [Blower Motor] w/o Wheel, w/AC; w/o Wheel, w/o AC; w/O.E.# {3556601 Or 3556602}; w/O.E.# {3773389 Or 3773390}
READY-AIRE 5231 [Blower Motor] w/o Wheel, w/o AC; w/O.E.# {3556601 Or 3556602}
FACTORY AIR 35555 [BM Motor - w/ AC] Deluxe Heater-Stamped-3773389, 390
FACTORY AIR 35555 [BM Motor - w/o AC] Deluxe Heater-Stamped-3773389, 390
FACTORY AIR 35555 [BM Motor - w/ AC] Std Heater; Stamped-3556601, 602
FACTORY AIR 35537 [BM Motor - w/o AC] Std Heater; Stamped-3556601, 602
FRIGETTE CORP. 240-231 [Blower Motor] OE# 3620822; (Includes w/Std. Heater Only, Mtr. Stamped 3556601 or 3556602); (Includes A/C)
FRIGETTE CORP. 240-308 [Blower Motor] w/Deluxe Heater Only; OE# 4094016; Mtr. Stamped 3773389 or 3773390
FRIGETTE CORP. 240-130 [Blower Motor] w/Frigiking A/C
FOUR SEASONS 35555 [BM Motor - w/ AC] Deluxe Heater-Stamped-3773389, 390
FOUR SEASONS 35555 [BM Motor - w/o AC] Deluxe Heater-Stamped-3773389, 390
FOUR SEASONS 35555 [BM Motor - w/ AC] Std Heater; Stamped-3556601, 602
FOUR SEASONS 35537 [BM Motor - w/o AC] Std Heater; Stamped-3556601, 602
HALLMARK PRODUCTS CO 41-56 [Blower Motor-Reman] 1 Per Veh; W/O AC;
MURRAY 208991 [Blower Motor] w/ A/C or Exc A/C
PARTS MASTER 35555 [BM Motor - w/ AC] Deluxe Heater-Stamped-3773389, 390
PARTS MASTER 35555 [BM Motor - w/o AC] Deluxe Heater-Stamped-3773389, 390
PARTS MASTER 35555 [BM Motor - w/ AC] Std Heater; Stamped-3556601, 602
PARTS MASTER 35537 [BM Motor - w/o AC] Std Heater; Stamped-3556601, 602
SIEMENS PM 230 [Blower Motor] w/AC; w/factory equipped AC & w/o AC; Includes Blower Wheel
SIEMENS PM 230 [Blower Motor] w/o AC; w/factory equipped AC & w/o AC; Includes Blower Wheel
TEXAS AUTO AIR PARTS 2-321 [Blower Motor-New] 1 Per Veh; W/O AC; W/1-1/2 (38mm) Shaft;
TEXAS AUTO AIR PARTS 2-323 [Blower Motor-New] 1 Per Veh; W/O AC; W/AC; W/2-1/2 Shaft;
TRUST 41-56 [Blower Motor-Reman] 4X4; W/O AC
TRUST 41-56 [Blower Motor-Reman] W/O AC
TRUST 333818 [Blower Motor]

 

[william]

Wow,
Thanks guys! I am going to try and order up a motor on monday. I pulled the old one, it was an aftermarket unit, but I am not sure how old. I tried lubing the bushings on a longshot, but it didn't seem to help. I removed the metal cage fan, and it would run all day and the fuse would not heat up. Once I put the fan back on, it would only run on low without the fuse getting hot. Med or hi with the fan attached and it got firecracker hot in a matter of seconds. I did notice that the clips that the fuse goes into are badly scorched. The rivet that attaches to the wire is still tight, but the metal that clips the fuse in is in poor shape. I tried to clean it up with a file, but it just won't turn shiny.
I am going to try and bypass the factory fuse and install an inline style to see if that is the trouble. If not, a new motor it is. Judging by the fuse blocks I have seen in most 70's trucks, this is a common issue. If I can definitively figure it out, I will do a how to or something. Thanks again....
william

 

[macario]

Pull the motor out of the housing and run it. See if it blows the fuse then. If not, it could be rubbing against the housing somewhere inside and causing the motor to pop fuses.

Mac

 

[Chump]

couple of other things...make sure the ground for the motor is good and when you ran new wire was it the same gauge or better yet, bigger gauge. That fuse has always been a problem and the fuse block melting. they should have put relays in years ago but these were trucks and relays were too chic in them.

 

[4dr4x4]

Does the heater blow the fuse just when the switch is on the high setting or both? Try removing the ballast and see if any of the coils are touching each other. If so they will get red hot. I spread the coils apart, on the ballast in my truck and it seemed to reduce the heat alot. I also used a fuse style breaker, that will reset if it ever did get too hot. That breaker wouldn't be a good idea if it's still popping every 10 minutes.

 

[william]

The heater will run fine on low speed, but medium or high the fuse gets hot fast. I removed the motor and ran it outside the heater box, and it still got hot on med & hi. With the fan removed from the shaft, the motor ran at hi speed with no problem. Grrr....

 

[william]

I decided to bypass the fuse, as the stock holder was pretty ugly from all the previous overheating. I pulled the heater wire off the end of the fuse block, added a heavy gauge wire from the key hot "bus" on the fuse block, and put connectors on either end to accept a chip style fuse or breaker. Problem solved, the heater will run all day now and not burn the fuse! Thanks for the idea 4dr4x4.
william