99 Yukon AC Blower & HVAC Panel Not Working

[McDermut]

Hello all!

So I've had this issue(or issues) for about a little under a year now, but it all finally completely went kaput a couple months ago. The issues I've had are:

- The AC blower motor started making a type of very loud harsh grinding noise intermittently when the AC or heater was on. It started happening more often as the weeks went on. I know, should've addressed it then but I hardly drove it because of college.
- After a certain point a few months ago, the HVAC fan control started malfunctioning. The blower would only "work" when the fan was on high and even then it was mostly intermittent with the noise. There's still hot and cold coming from the vents but of course its not much without airflow.
- When I'd drive around town or especially on the highway once I get above 45 I can hear a fainter, sporadic grinding noise coming from the blower motor. This even happens when I have the fan setting on "off".
- I've unplugged the black wire+plug that is located above the blower motor "hub", and is quite visible and accessible when you remove the glove box. It's reduced the number of times and how much the noise occurs but it still happens.

All of that possibly confusing information into account, I'm quite certain my blower motor is done for. I suspect my resistor is also in need of replacement and possibly my HVAC control panel as well, though it would be nice if it didn't need to be as those can get expensive.

I'd like to get a working AC in the truck as summer has already rolled in and I'm tired with trying to stay cool the old fashioned way. Any comments and advice would be greatly appreciated!

 

[Joseph Garcia]

It sounds to me like the blower motor is shot. I would remove the blower motor and check it for free movement/rotation. I'm thinking that you will find that there is rotational resistance and 'noise', which there should not be, signifying that the bearing is shot. If there was rotational resistance, due to the bearing being shot, there was most likely an extra load placed on the speed control resistors, thus weakening them.

My recommendation is that you consider replacing both the blower motor and the speed control resistors.

Other folks will chime in with their suggestions.

 

[1BADI5]

I went through this last summer after I completely replace the whole AC system. The next day, nothing worked. I pressure checked the system, checked for leaks or loose connections.........it was the actual control panel. That cheap 90's plastic and electronics were toast.

I bought a new one at Autozone, I think it was around $165. And that fixed my issue

 

[OR VietVet]

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I see items like this in your future. Definitely the blower motor and wheel, the resistor set-ups, there appears to be two choices so look carefully.

The controller is also a choice of 4 so look at them all at RA.


We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.

 

[McDermut]

I see items like this in your future. Definitely the blower motor and wheel, the resistor set-ups, there appears to be two choices so look carefully.

The controller is also a choice of 4 so look at them all at RA.


We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.

Thank you very much! I've pulled the blower motor and it's most definitely dead.

I appreciate the tip about vehicle info, I'm still trying to upload a pic of my RPO codes to my signature, but I've updated it to have at least basic info at the moment. I certainly understand how that can be helpful.

 

[McDermut]

It sounds to me like the blower motor is shot. I would remove the blower motor and check it for free movement/rotation. I'm thinking that you will find that there is rotational resistance and 'noise', which there should not be, signifying that the bearing is shot. If there was rotational resistance, due to the bearing being shot, there was most likely an extra load placed on the speed control resistors, thus weakening them.

My recommendation is that you consider replacing both the blower motor and the speed control resistors.

Other folks will chime in with their suggestions.

Thank you! I pulled the blower motor and it was completely shot. Somehow water got in and rusted the lower half of the interior motor mechanism. The rod was broken off from the motor and the plastic fan had broken off completely and even worn down some of the housing plastic. You can see in the last pic how badly the water affected the motor.

 

[OR VietVet]

Thank you very much! I've pulled the blower motor and it's most definitely dead.

I appreciate the tip about vehicle info, I'm still trying to upload a pic of my RPO codes to my signature, but I've updated it to have at least basic info at the moment. I certainly understand how that can be helpful.

The entire RPO sticker is not that important. The RPO for engine, trans, axles/gears and suspension is fine and then others as needed depending on what your post for help is all about.

 

[Joseph Garcia]

When uploading photos, there is a photo file size limitation for this Forum. Today's cell phone cameras often generate a photo file that greatly exceeds the file size limitation on this Forum, so that might be the cause or your upload issue.

 

[McDermut]

Thanks for the advice!

I'm still trying to figure out how water got that far in the first place.

 

[mrtahoe42]

did that fix your issue cause im having some of the same problems . i know my blower motor is shot cause its making a noise but when i put my ac control on max and have both button pushed in it only on the floor then if i just have the ac button pushed it and it off max it blows threw the vents

 

[McDermut]

did that fix your issue cause im having some of the same problems . i know my blower motor is shot cause its making a noise but when i put my ac control on max and have both button pushed in it only on the floor then if i just have the ac button pushed it and it off max it blows threw the vents

It did. I replaced the blower motor and blower motor resistor which has solved my HVAC problems. For my truck when you have the blower on max with both the AC and cabin circulation buttons pushed the flap behind the blower motor opens which makes the motor more audible. When you switch the blower dial down or push off the cabin circulation button the flap closes some or completely and the sound goes down some. The flap is used in cabin air circulation and for my year and make has no cabin filter, others may be different.

 

[east302]

Thanks for the advice!

I'm still trying to figure out how water got that far in the first place.

Remove the blower and use a mirror to look up through the air intake. There’s a screw there that can let water leak in and it’s a straight shot to the blower. Have someone run a hose on the lower windshield and see if water comes in there.

Any new blower will eventually seize if the leak isn’t fixed.

Not the best picture, but the screw is here. It threads into the blower intake. Remove it, goober it up with silicone or RTV and reinstall.