91.5 Blower motor issues

[JHylton]

The blower motor in my late 91 has quit working. Before I take apart the dash or pull the blower motor, I'd like to make sure the resistor is not bad, as it is easy to get to. How does a person check to see if it is working? There are several wires connected to it and I need to know what to/how to check this first. Thanks !

 

[RWherley]

ok a few things, your blower motor should be under the hood on the right side of the truck behind the black insulation bolted to the fire wall, easiest way to test it is to just pull apart the 2 wire plug at the motor and supply power and ground and see what happens, also check the blower activation switch i had that fail on me already, its part of the push button mode selector in the dash but its not serviceable if it failed you either have to by pass it with a separate switch or get a whole new selector switch.

 

[B.G. Smith]

Even if the resistor goes the high setting bypasses the resistor, should run on high setting? Of course if it doesn't run on high you have to do the hot wire check. bg

 

[JHylton]

Thanks for the suggestions. Hopefully this weekend I will get a chance to work on it.

 

[JHylton]

Thanks for the suggestions. Hopefully this weekend I will get a chance to work on it.

Finally had a chance to do some trouble shooting. I found the wiring schematic in my shop manual and pulled the connector at the resistor, inside the cab, and easy to reach. I have no power to any of the connectors at any of the speed selections from the switch. I figured this was this easiest step to eliminate.....so......I guess taking the dash apart to get to the switch is next step......One step at a time

 

[Ozymandias]

Short question, is the blower motor regulation on the Plus or the Ground Side?
I see them often on Ground Side and then, well, you dont see any power on the Resistor and the Switch.

Could be possible.

 

[B.G. Smith]

If you can get to it, check the wire harness connector at the ignition switch. The blower motor is the biggest amp load that goes through the ignition switch and sometimes melts the connector.
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[JDancoe]

When I first started working at a Chrysler – Plymouth dealership in the mid 1960’s, most Mopars had a “High Blower Relay” incorporated in the heater blower circuit. By the early 1970’s they were no longer used. (My new 1972 Dodge pickup didn’t have one)

It became common for Mopars to burn out the blower speed control switch, and/or melt the molded plastic connector, plugged on to the blower switch, at the back of the Heater/AC control panel.

See the attached photos of the heater control.

The blower speed control switch is still available. NAPA has an Echlin brand switch,
P/N: ECH HC200, RockAuto also lists them in their on-line catalog. I would imagine most other parts store have, or can get them.


I’m attaching some photos of the A/C-Heater switch assy.
Also, a photo of the Blower location on the Right side of the Engine side of the firewall, that also shows where I mounted the Hi-Blower Relay on my truck (and others).


I am also attaching schematics of the A/C – Heater blower wiring, and a modified schematic illustrating the modifications to the wiring to incorporate the relay.


What the relay does is allow the lower speeds to operate as normal through the switch and resistor, but in “Hi-Blower” mode, the motor is supplied with direct 12V power through the relay, thereby relieving the dash switch on the A/C control panel,
and the Ignition switch accessory circuit, from having to carry the high amperage load.

It seems to me, and to other people whose vehicles have been modified in this manner, that the blower also turns faster, and pushes more air. I don’t have any way of measuring the blower speed, so I can’t verify that aspect.

One note of caution.
If you should somehow reverse the (2) leads to the blower motor, the blower will run backwards! It will sound normal but it won’t move any air through the ducts into the cab. Not a real big deal, just swap the wires.

I hope you find this of some help.

Jack Dancoe

 

[JHylton]

Update....Finally got a few minutes to further trouble shoot this issue. The blower motor is good. Hooked up direct power to it and it runs fine. reversed the hot/ground just for grins, and it runs fine in reverse. Next stop: switch in the dash.......I will post upgrade once I get into that !!

 

[JHylton]

If you can get to it, check the wire harness connector at the ignition switch. The blower motor is the biggest amp load that goes through the ignition switch and sometimes melts the connector.
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I finally got around to working on this the last two days. I am not getting any power at fuse #1, the fuse that controls the heater/ac subsystem. I d

 

[JHylton]

I finally got around to working on this the last two days. I am not getting any power at fuse #1, the fuse that controls the heater/ac subsystem. I did get to the connector at the ignition switch and I do not have any power there....I have power at the lead coming off the positive post at the battery, going thru the first fusible link. Somewhere between fusible link and ignition switch, power is lost. On a more positive note, I did get the headlight switch changed out and I now have instrument panel lights with dim capability !!!

 

[JHylton]

Got it fixed. Fusible link was broken.....it was about to break off from the Y connector where all the fusible links are distributed. I installed an inline fuse in lieu of the fusible link. Heater motor works great now. Next fix is getting the goofy speedometer to work correctly. As soon as you start it and put it in gear, it jumps to 120 then oscillates wildly while driving.