How to Replace Blower Motor Resistor

[JohnBravo]

Mine is doing the same thing intermittently. Last week I replaced the resistor and blower motor, but the fan speed still doesn't always work as it should. When I turn the other two knobs I can hear something happening (heat/cool and the blend-door moving), but the fan speed cuts in and out on all speeds. I'm assuming that by replacing the switch I should be good to go...had been shopping for the whole assembly (ACDelco 15-72548) but I can't swing $125 right now...

 

[ThundahBeagle]

Hello everyone,

New to this forum, but I have done this recently, just yesterday. I had the classic signs of blower only working on High. In my case, I also had a tapping sound from behind the glove for 30 seconds when ignition was turned on or off, and eventually, a bad bearing in the motor evidenced by rough spinning noise.

That's three separate issues, and I lived with each until the fan completely stopped spinning and I froze last winter.

The tapping was the blend flap actuator. Real pain in the ass to reach the top 7mm bolt, but I swapped it out.

The blower screeching and finally stopping was obviously the blower bearing. Replaced the blower, which was more of a pain than it should have been for a truck. Had to remove the ecu computer in order to peel off the insulated rubber, to then unbolt it and jimmy it out. It's right there. Shouldn't be obstructed, but it is, and just enough.

The blower only working on high was the resistor. Swapping that out is easy, especially with a boxed 7mm wrench or even easier with a ratcheting box wrench.

Now, the heat is absolutely CRANKIN' again.

QUESTION: Is the resistor supposed to glow red hot on the medium setting? I happened to catch a glimpse of that because I tested functionality before completely bolting it down. I understand that the resistor is bypassed on the high setting, and it works hardest on the low setting, but mine glows, and only glows when set to medium...

Please let me know.

Thanks in advance.

 

[Eveready]

The resistor is essentially a heating element that the switch places in series with the blower motor and thus reduces the current to the motor for the slower speed. A glow from a resistor built that way would not be unusual. If the blower works on all speeds then most likely it is working as it should. I recently replaced my resistor for the same reasons.

 

[Eveready]

As they say down at the dairy ... one udder thing.. (thud..Crash) Since so freakin' many pictures have been crapped up by photobucket I thought it might be a good thing to show folks what the resistor actually looks like .. so here it is in all its glory. This is the one for 3 speeds.

You must be registered for see images attach

 

[1500z71]

This sounds right up my alley. My truck sat for a good while getting the bed side repainted and when I got it back, the fan on low wouldn’t work at all and still doesn’t. At the same time the a/c compressor won’t engage itself either, so not cold air. I’ve made sure that the compressor is charged up, and swapped out the head unit and blower motor on the hvac with a new blower and a different head unit, issues continue. I guess this would be my next step?

 

[Skimmilkman]

Yukon, What was the problem with yours when you had to tap it? That's what mine does. Bump it, it comes on and runs fine... ?

Old thread, but to help others that may find their way here...

In both my '97 Tahoe and '96 Suburban, the blower would totally cut out, then back on, then off, at all speed settings. When it would not work, a slight tap or kick to the passenger-side under the dash usually got them running for a little bit.

In the '96 Suburban, I found the single power wire that connects to the blower motor had worked it's way loose. Pressing the spade-connection more solidly together resolved that.

In my '97 Tahoe, the bad connection was between the spade connector and the inside of the motor housing, buried in the rubber encasing the spade connector to the interior wiring inside the motor. While I cut away the rubber and added solder to the area in order to resolve the issue (2 months ago), I'm inclined to suggest replacing the motor if this is your problem.

 

[shownshine55]

1994 suburban, the heat works when it wants to. When it works, all speeds work and it will melt your face. sometimes it is working just fine. shut off the engine and it doesn't work. Shut it off, it might work again. While it is not working, hit a bump and it might start up. I took out the resistor and it looks clean. No corrosion or rust. Should I be looking at something else?

 

[Donald Mitchell]

Another thing that you should do while you have the blower out is clean out the evaporator. You can reach in thru the blower opening and pull a lot of crap, I then got my shop vac and got the leaves cat hair cleaned out and next I going to spray it down with coil cleaner and let it sit then try to flush everything out. Tip, take out the 13mm Dash bolt where the hook is on the end of the dash next to the door. You can then pry the hook out enough to pull the dash out a little and get the blower free.

 

[Tim W]

Question....last week i replaced my resistor because I lost my low fan setting. Well I lost my low again. What could be causing me to lose resistors?

 

[Donald Mitchell]

A bad blower motor or some other short. Or the control has problems.