Replacing Blower Motor Resistor

[SunlitComet]

Replace your blower switch and inspect and repair the wired connecter for it if necessary.

 

[willie1280]

I replaced the blower switch and that fixed the blower not turning off issue.

However, i still cannot turn off the A/C compressor, it appears to stay engaged all the time. It also squeals horribly yet.

 

[willie1280]

Well took the truck in and the compressor was shot. They replaced compressor, but now the compressor runs constant regardless of what the system is set at. He said i should take it to the dealer for a computer reprogramming.....what does that cost???

 

[SunlitComet]

Damn it there is no reprogramming. If the compressor never shuts off even with the a/c fuses pulled you either have a 12v+ shorting to the a/c request circuit to the PCM or the PCM is damaged or the clutch relay is shorting causing a constant voltage feed to the clutch. or the head unit has suffered damage as is sending a A/C request to the PCM regardless of switch position. Look at some of the previous A/C posts where I have wiring diagrams posted for help tracking it down. If you need troubleshooting charts for a specific issue let me know and I will forward what I have.

 

[swensor]

I've had a similar problem - fan control either erratic or none at all. I replaced the switch and found some heat damage to the connector. The new switch worked perfectly ... for about a minute and now its dead. The fuse is not blown, and there is no evidence of heat damage to the new switch, when I pulled it out to check it.

Why is Off/Low/Medium/High on a 12 volt DC motor so complicated?

I pulled the resistor and it looks clean and shiny, but I have no way to check it.

Anyone have any ideas of what to try next?

Thanks.

 

[SunlitComet]

are all speeds dead?
and what year?

 

[swensor]

Thanks, Sunlitcomet. Yup, all speeds are dead. Its a '97 Tahoe 1500 LT 4 WD 4 door.
The plug-in part of the wiring harness was a bit melted, and insulation on the brown wire was melted back about 1 mm, but the wire looked in tact. I cleaned up the contacts on the plug the best I could, but it wasn't perfect.

 

[SunlitComet]

Check your heater hvac fuse.

 

[swensor]

The heater HVAC fuse is OK. I pulled out the switch wiring harness and cleaned the plug contacts very well and put it all back together. Low speed - OK, Med - OK, High -OK, Off - OK ... then dead as doornail again!

What does the relay near the resistor do, and could that be the culprit?

 

[swensor]

I give. Having replaced the switch, $24, the relay, $25, and now th resistor, $35, but still no joy. Anyone know if I can jury-rig an on / off switch with 12v DC directly to the blower (which I know works) through the two female clip leads on the blower to make it work. One lead is purple and the other black. Hoping its positive and ground sounds way too optimistic, as the motor is likely grounded to the frame. All I want is the defroster and heater to work on this old clunker. Any advice would be appreciated. Thanks.

 

[SunlitComet]

that relays determines if slower speeds on blower from switch and resistor work or it connects directly to system voltage for high speed. you have a multimeter around I presume.

 

[swensor]

Problem solved! After cleaning the contacts on the plug from the wiring harness that goes to the switch, I silver soldered the contacts, as they looked a bit heat damaged. When I plugged everything back together, eureka! In retrospect, I didn't need the resistor or the relay, but still saved a couple hundred $ over what the dealer estimated it would cost to have it repaired.

 

[SunlitComet]

They actually sell those pigtails with terminals and connector if it will make you feel better about perhaps just replacing it. They get burned up becuase of the current and vibration.

 

[jathon0815]

I had to replace this the other day on my '97 Tahoe LT (4DR) and couldn't find a thread with pictures, so, here goes...

Tools:

• 7mm Wrench
• 7mm Socket (1/4" Drive)
• 1/4" Drive Ratchet (small as you can find)
• New blower motor resistor ($17 at O'Reilly's)

1. Gain access to the resistor by pushing in on the right side of the opened glove box. With a little effort, it should drop free. Lift it up off the hinges and set it out of the way.


View attachment 4593


2. Looking through the glove box opening, you can see the HVAC box. Look on top of the HVAC box and a little to the left and you will see the blower motor resistor mounted snuggly.


View attachment 4594

3. Unplug the electrical connector and begin removing the screws. I found it easier to start with the 7mm wrench to get it loose and then squeeze the ratchet in there to screw it out the rest of the way. There is a third screw on the front of the metal bracket to the left that will have come out as well.


View attachment 4595

View attachment 4596

4. After removing the three screws and the metal bracket, pull the old resistor out, tilting it sideways and then sliding it toward you. You might bend the coils a little but this is ok.

5. Your new resistor should come with a new gasket. Do not forget to put this on the new resistor. Tilt the new resistor sideways and slide it into position carefully (you might have to bend the coils gently again). Make sure it seats properly.

6. Reinstall the two screws holding it in place (start with the wrench and tighten with the ratchet) and plug the electrical connector back in. If you want, you can reinstall the useless metal bracket. I left it out. I think it's suppose to hold a relay and the resistor in place, but I didn't see a need for it.

7. Set your glove box back on the hinges and slam it closed. Your done.

Now go have a beer.

I had this same issue. Only the HI setting on my blower switch worked. Found this thread and forum via an Intarwebs search. Saved me a trip to the Stealer-ship. Thank you and the pictures helped a ton!

 

[MarcT]

Thank you to the OP. This procedure worked great, it saved me a bundle of $$ and/or a real hassle. The service manual has a procedure that has you jumping all over the books ands taking half the dash apart. If I hadn't found this I would have taken it in.
Only downside was losing one screw down the backside of the heater case due to fat fingers...

 

[nimrodcs]

No problem gentlemen, that's what this forum is for.

Only downside was losing one screw down the backside of the heater case due to fat fingers...

Lol. I have that same problem sometimes....

 

[95escahoe]

Did this a few months back, its pretty straight forward just looked it up on YouTube its such a pain to get back there

Sent from my HTC One X using Tapatalk 2

 

[Scoregasm12]

are all speeds dead?
and what year?

I realize this is a old thread, but am hoping for any advice. I have a 95 tahoe. My blower just stopped working and prior to that my blower wouldn't work on 3 but all else worked fine. I replaced the resister for that reason the 3 not working. still nothing, so replaced my motor and fan, still nothing checked my control panel the wiring for the fan were fried so i replaced that as well and still no power to the motor. All fuses were perfectly fine as well