Question about 1999 GMC Suburban

4 Answers

99 Yukon - Blower Motor Not Working

Hi ... Having issues with blower fan on 99 GMC Yukon … hope there are some experts out here that can help.

99 GMC Yukon SLT 4WD – Front and Rear AC

Issue: Drove the truck to destination and blower worked fine when truck was shut off. Got in it to leave and turned on heat on but no blower. Blower does not run in any of the four positions of the Control Switch. I have checked fuses but all are good. I originally suspected it was the blower motor but now am stumped!

Took the fan motor out and tested voltage. Here's what I saw which, to me, is strange.

There are four ''knotches'' on the rotary switch corresponding to fan speed ... right? Defined in the schematic as Lo, M1, M2 & Hi. Below is the voltage I see at each setting using a digital meter.

Off - Zero Volts
Low - 8v but climbs slowly to about 9v
M1 - 11.7v
M2 - 11.45v
Hi - Zero Volts
Note: When I turned to a lower setting from any higher setting the voltage drops dramatically and then slowly climbs back to the values from above.

I have now replaced both the Fan Motor, the High Blower Relay with no avail or change in voltages.

I removed the Blower Resistor and check for continuity across all of the various coils and the one resistor. All are good.

The only thing I have not replaced/tested is the HVAC Control Module which includes the rotary switch.

Other notes:

I have checked wiring harness around the heater housing for signs of overheating. No visible signs.
Change other rotary switch for air deflection and the appropriate doors open or close. I can hear them.
The Recirculation button works fine as I can also hear/see the door operate.
Rear AC fan works fine.


1. I understand a common problem is that if the resistor goes bad, the fan may only operate on Hi. I am seeing the opposite. Should I be seeing continuity across all poles on the resistor?
2. Couldn’t I hook the fan to a 12v power source and it should run? Haven’t done it yet, afraid of frying the brushes but seemed like a basic test.
3. Should the HVAC Control Module be the next focus? Is it a pain in the **** to remove?
4. Am I delving too deep here and missing something obvious?

So I'm somewhat stumped. Wondered if anyone you had any specific recommendations based on the above info.

Thank you in advance ... hope you had a great Thanksgiving.


Posted by on

  • Anonymous Dec 28, 2008


  • Anonymous Jan 24, 2009

    I have the same exact problem, my blower was working on a very cold morning, then all of a sudden it went out and has not come back on. I have change almost everything dealing with the heating and cooling system. Expect the blower.


4 Answers

  • Level 1:

    An expert who has achieved level 1.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer

I went through the same thing with my 99 suburban. It turned out to be the dash fan control switch. It is purchased seperate from the whole cluster for under twenty dollars. The instrument panel cover comes off gently by hand with the tilt steering in the down position. You have to then unplug the electrical plugs to get it out of the way. The heater ac control panel then comes out by hand far enough to unsrew the heater fan control from the back.

Posted on Jan 24, 2009

  • Level 1:

    An expert who has achieved level 1.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer

If you have already changed the blower motor, than ignore my comment. My 99 Suburban blower didn't work on low speed, only medium high and high. I thought it was the resistor pack, so I changed it. The low speeds then worked, but I quickly noticed a burning smell at the two lowest speeds. I turned it off quick not to burn up the new resistor pack. I noticed one terminal of the fan switch wire connector looked to have gotten very hot in the past. I changed the fan switch but no change in symptoms. Still smelt like burning at low speeds. The motor appeared to work fine durning all this, but with nothing else to try we swapped out the motor for a new one and that sloved all the problems. The original motor was wearing out and though running fine was pulling to many amps through the fan switch and resistor pack. For those that haven't replaced the blower motor yet, I'd advise doing this as preventative maintaince so you don't burn up the resistor pack, fan switch, or wiring.

Posted on Dec 21, 2009

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 5 achievements.


    An expert whose answer got voted for 20 times.


    An expert who has answered 20 questions.

  • Expert
  • 71 Answers

The power supply in the blower circuit feeds to the blower first so at the blower there should be 12 volts at the feed line. I think purple. Power then goes thru the resistor to the blower switch. By pulling the switch and checking the wires from the resistor you should have power on each one. Then there is a ground that comes off the switch to complete the circuit. Make sure that this is a good ground. Sometimes the harness connector on the back of the switch gets burned. You can hook the blower to a 12 volt source, just put a 20 amp inline fuse in the wire.

Posted on Dec 01, 2008

  • SM124 Dec 02, 2008

    I checked the wrong diagram. It feeds thru the switch first, then the resistor, then the relay to the blower. If you have the voltage on the ground side of the motor you have a bad ground. Try running an extra ground wire just to see.


  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

I have been back an forth on this site several times and for MY issue it finally helped me fix it. I started with the issue of the blower only blowing on high no matter what the setting....I replaced the resistor and no change. It would never shut off in off mode though? (That should have immediately prompted a replacement of the switch). I then ended up with the blower NOT RUNNING AT ALL OF COURSE ON THE COLDEST DAY OF THE WINTER SO FAR. I did a circuit test at the purple wire and was boggled because I had power to the line through all BUT HIGH? Weird that the low was actually the highest voltage? I then replaced the blower motor because it appeared to be the next step but still no change. I switched out the relay also... NO CHANGE. Finally, I replaced the control switch. VOILA!!!!! Now I have all my speeds working well, a VERY TOASTY-WARM SUBURBAN, and a happy wife. In reflection I would say that if you have the same issues that I did at the front....then start with the control switch first and work past that. ALSO be very aware of the wiring behind the control switch (I taped a short on a wire while replacing on the dash).
All in all here is the cost...Resistor $16, Blower Motor $49, Relay $20, Control Switch $20....Heat in family primary grocery getter...PRICELESS!!! But like I said before. If this occurred again in another truck I would start with the switch and move from there. I do think that my Blower Motor needed replaced anyway just to be safe, my resistor was bad at some point... But I think the relay was not needed. All this was relatively easy to replace (worst was resistor just because of tight fit.) Do no lose heart. You can complete it just keep going. AND IF POSSIBLE BORROW A HEATED GARAGE TO FIX IT.

Posted on Dec 30, 2012

1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Front ac blower wont shut off after the truck is shut off

This would indicate to me the vehicle has had an issue with the wiring, perhaps an accident in the front end, and someone has hooked up the wires wrong.
The radiator-cooling electric fan can run up to several minutes after you shut off the engine, as it is cooling off the cooling system.
The A/C fan, however, should shut off with the engine.
God bless your efforts.

Sep 07, 2015 | 2003 GMC Yukon XL 1500 SLT

1 Answer

My gmc yukon 2000 slt rear ac blows hot air when i have ac . on and the front works fine .

I have a 2000 GMC Savana Van SLT with front and rear AC/Heat. My front would blow hot while the rear blew cold with AC on. It turned out to be low on Freon. It's hard to know if you have the right amount of freon installed because pressures vary depending on the ambient temperatures. So the best way is to remove all the freon then reinstall the recommended amount as listed on the evaporator housing near the firewall. This worked fine for me... works like new after installing the correct amount of freon.

Jul 01, 2014 | 2000 GMC Sierra

1 Answer

Yukon rear air conditioning

There's a rear hvac fuse 30amp that powers an auxillary blower motor processor controller. The controller has the resistor to regulate fan speed. The front and rear fan control both pass thru the front controller first then to the rear processor.
You may need a shop manual to be able to diagnose the problem.

Jul 23, 2013 | Cars & Trucks

1 Answer

Hi, I have a 2005 GMC Yukon XL SLT with almost all the bells and whistles. Currently I am having an issue with the rear air conditioning system. The front works great but in the back it only blows hot...

Hello Randal.

I suspect if you have most bells and whistles your Yukon has automatic temperature controls.
I went through the diagrams and service bulletins. Nothing in bulletins relating to your issue.

These systems are complicated. They are operated both by computer data and analog systems, and as you are aware, from two different control panels.
The wiring diagrams for the heating/ac system is 8 pages.
If you have not yet done so, check fuses related to heating and AC.

There may be codes stored in the body control computer that will help pinpoint the problem.
It may be as simple as a jammed heat door or a bad motor that operates it.

I could make guesses for hours but ultimately you may need to bite the bullet on this repair and take it to a qualified HVAC technician.

I wish I had a better answer for you. Keep trying to find a tech here if you like.
There is my opinion Randal, thank you for listening and using FixYa.


Dec 31, 2010 | 2003 Chevrolet Suburban 1500

1 Answer

2004 gmc yukon xl denali front a/c blower not working

ac on a 2005 gmc yukon not blowing and cant here compressor the rear ac of the truck is working fine, are there any fuses i can check?

Jun 28, 2010 | 2005 GMC Yukon Xl Denali

1 Answer

Heater fan on 2002 Yukon does not operate in front, only rear.

The front blower motor is controlled by the blower resistor module.This is usually the problem with the front blower not working.I looked up the schecmatics and I don`t see separate fuses for the front and rear.But the fuse for the front blower is in the under hood fuse block.If this is good then The problem is probably the resistor module.It is next to the blower motor.The connector from the resistor connects to the blower motor.If you want to confirm this you can check for power and ground at the blower motor connector when you activating the blower switch on.This can be done with a test light.Make sure you have power going into the resistor module also.If you have power going in and no power at the blower motor then replace the resistor.Hope this helps.Good luck.

Dec 28, 2009 | 2002 GMC Sierra C/K1500

2 Answers

Blower fan on a/c quit blowing in front but still blows and blows cold air in back

first off make sure you have no blown fuse. but front blower motor may be bad. if it does not work in any speedyou can check for power at the wires going to the blower. under dash on passenger side

Aug 10, 2009 | 1999 GMC Yukon

2 Answers

I have a 2004 GMC Yukon with auto climate control. The front a/c is working but the fan will not come on. The rear a/s works fine. Checked fuses, they are all good. Any suggestions?

It's most likely your blower motor control module. Easy fix! Remove the kick plate under the glove compartment and the module is right next to your blower motor - remove the two screws and it will drop right out. Disconnect the wire harness (2 wires) and replace. Good luck!

Jul 28, 2009 | 2003 GMC Yukon

1 Answer

99 Yukon - Blower Motor Not Working

replace the A/C control head... very simple to do. Pop off the dash panel and pull the control head out... unplug the 3 harnesses and there you go.

Jun 02, 2009 | 1999 GMC Suburban

Not finding what you are looking for?
1999 GMC Suburban Logo

4,417 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts


Level 3 Expert

74192 Answers


Level 3 Expert

1311 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22082 Answers

Are you a GMC Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides