Replacing Blower Motor Resistor

[nimrodcs]

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.


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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.


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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.


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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.

[drowndindreams]

did it come out dirty? only reason i ask is because it feels like my air doesn't blow as high as it used to.

[nimrodcs]

It wasn't too bad. A little oxidation here and there.

My blower motor is running constantly. It won't change speeds or turn off. I thought replacing this would fix my problem, but it didn't. Now I have to find time to pull the control unit out of the dash and look for corrosion or check the relays related to the blower.

drowndindreams, yours could be the resistor or maybe your blower motor itself is going out.

Here's the old resistor:

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[fyremanpat]

was it running constantly before replacing the resistor? if not then you may have 2 of the coils touching on the resistor when you put it back in.

[nimrodcs]

Yeah, I bought the 'Hoe back in 12/09 with the blower constantly running. Just got around to fixing it, hoping the resistor would solve it. I'm about 99% positive the coils aren't touching, though.

[nimrodcs]

Well, I pulled the control unit out of the dash and found some pretty nasty stuff. There's a bunch of corrosion on the circuit board. The fan speed switch and the wire harness that plugs into it looks like they have gotten very hot at one point.

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I cleaned the circuit board the best I could, and also the pins in the switch and harness. Hooked it all back up. It changes speeds now, sometimes. But it still wont turn off. I'm gonna replace the fan speed switch with a new one. I just don't know if I should replace the wire harness in the dash or not. Any suggestions?

[fyremanpat]

thats not corrosion something got hot and melted..i had the same problem.

[nimrodcs]

I know the switch and wire harness got hot and melted a bit, why, I do not know. It was rust and corrosion on the circuit board....cleaned up really good. I'm sure I can get a new switch at the parts store, but still pondering using the old harness...

fyremanpat, did you replace your harness, or was the old one fine?

[fyremanpat]

i cleaned up the harness the best i could and re used it. I had to go it the harness and open up the connections so they made better contact.. you probably will have to ebay a whole new assembly not just a switch.

[mackysasser]

Before I found this post I thought it was only the blower so I got a new one.....

I hooked it up but didn't re-install and it won't power on......I put a voltage meter to the wires and there is juice to it when I am in low/med/high, how much though I don't know........

I replaced the resistor next and still nothing but the voltage meter spikes...

I had the blower tested at Napa and it works, there are no circuits out on the board either......I have not checked the switch but if I get power to the wires I assume it works.......

I live in Wyoming, its 30 degrees and snowing right now and I have no defrost or heat......any suggestions for what to try next...I hate giving my money to a shop if I can do it???????

THANKS! - Mack

[nimrodcs]

I'd check the fuse under the hood and then the relay next to the resistor. If it's getting power, it should be working. Maybe hook up a multimeter to see exactly how much juice it's gettin.

[vanilla_gorilla312]

I am having problems with the amount of volume coming out of the vents. All levels on my switch work, I cleaned out the evaporator, and installed a new blower. The air is around 25-30 deg. so it is cold. Just not a lot of volume coming out. Will this hopefully fix my problem??

[nimrodcs]

I am having problems with the amount of volume coming out of the vents. All levels on my switch work, I cleaned out the evaporator, and installed a new blower. The air is around 25-30 deg. so it is cold. Just not a lot of volume coming out. Will this hopefully fix my problem??

Have you replaced your cabin air filter? There's a thread somewhere on how to do this. Usually if its really dirty, it will restrict airflow.

[vanilla_gorilla312]

there aren't any in cabin filters for a 1997 Hoe. Is there?? If so I couldnt find them

[nimrodcs]

there aren't any in cabin filters for a 1997 Hoe. Is there?? If so I couldnt find them

I think your right, sorry. I think they were only in 2000-2002 trucks.

[shramek]

Hey, I just joined this forum. I am having problems with my 97 Tahoe's heater.. The temperature control module works for the temp and the different vent settings, but I can't control the speed. So I am only getting warm when I am driving. The fuse is good. I don't know if the control module is bad or if its the blower motor. It would be cheaper if its the blower. I don't know if this is a typical problem or not. Any help would be much appreciated, thanks.

[Rapunzl]

Thank you for the photos Nimrodcs! We went to the dealership and got a schematic that was supposedly for our 1999 Tahoe, but it didn't match at all. Now, we just have to check to see if it's the resistor or switch that have gone bad.

[SunlitComet]

:welcome: Rapunzl

[nimrodcs]

Thank you for the photos Nimrodcs! We went to the dealership and got a schematic that was supposedly for our 1999 Tahoe, but it didn't match at all. Now, we just have to check to see if it's the resistor or switch that have gone bad.


Since my last post, I have replaced the blower control switch, which solved my problem of the blower running constantly. Sorry for not posting sooner.

O'reilly's Part #: S15002

Autozone's Part #: SW1464

You basically just take off the instrument panel bezel, then take the AC/Heater control out of the dash and unbolt the switch from the back of it then replace with the new switch. Its pretty straight forward.

Hope you figure it out!

[willie1280]

Hey guys,

I have a 1999 Tahoe with similar issues. The first issue being that i cannot turn my blower off. Basically off and low are the same, the rest of the speeds adjust accordingly.

I am hoping this has something to do with my A/C not working as well. A few months ago the AC compressor would never turn off. I didn't know this was going on until one day while driving the compressor started squealing like crazy. The only way i could turn the compressor off was to disconnect the plug just above it.

So do you think i just need to replace the blower motor switch you reco'd??

Thanks
Matt

[SunlitComet]

:welcome: 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.