Diagnose-No Power/No Air Flowing In Rear Vents

crabbman · Oct 12, 2020

2002 GMC YUKON XLT. NO RESPONCE FROM CONTROL KNOBS LOCATED ON UPPER HEAD BOARD.
NO AIR, NO HEAT, NO COLD , NO FAN SOUND, AT THE THREE VENTS IN THE BACK PASSENGER AREA.
WHERE DO I START MY INVESTIGATION?
FUSE BOX?
SIDE KICK PANEL WHERE THE POWER CORD IS?
i will; wait for reply.
thank you.

Rocket Man · Oct 12, 2020

Did it just start failing or did you just notice? Either way the first thing to do when any electrical item in a vehicle stops working is to check the fuses.

crabbman · Oct 12, 2020

not sure but somehow my daughter says i have no air, no heat, no blower motor in the back passenger area. this is my daughters car and i am the official Mr. Fix it please .
yes i have checked a 10 and a 30 amp fuse which shows it is an a/c fuse. i am not finding a rear a/c seperate fuse location.
thank you, Rocket Man

crabbman · Oct 12, 2020

sorry i was able to look at the power connection cord located behind kick plate and i am not seeing any burned or frayed wires anywhere.

Rocket Man · Oct 12, 2020

Have you checked it yourself? The controls can be set to work from the rear or from the front. There’s several different types in our vehicles too- auto, non auto, digital etc. so maybe take a couple pictures.
Edit: there’s a separate fuse for the rear HVAC in the under hood fuse panel. Here’s a pic of my 02 Denali owners manual; the pen is pointing at the fuse, it’s labeled RR HVAC.

crabbman · Oct 12, 2020

yes, i rechecked my diagram and i found three fuses that work a/c. the fuses all look to be in working order. metal is not burned or cracked inside fuse

crabbman · Oct 12, 2020

crabbman · Oct 12, 2020

crabbman · Oct 12, 2020

thank you rocket man. not sure what you mean i can control the rear from the front. HERE ARE MY CONTROL KNOBS. LET ME KNOW HOW TO OPERATE THESE KNOBS?
thank you.

Doubeleive · Oct 12, 2020

you will have to proceed to checking the rear system then, you will want to check rear blower motor, rear blower motor resistor and rear control module.
this guy is a popular one, you can skip thru about the first half of the video, he is replacing a actuator but getting access to the rear is basically the same from 00-14

Rocket Man · Oct 12, 2020

Here’s another video that explains how the system works. I suspect you have a defective blower motor or resistor if the fuses are good and you get no fan blowing.

Here’s a link to another possible problem, check this connector in the driver side kick panel.

Rear blower motor resistor replacement.

And here's one on figuring out if its the resistor or motor. This video is for the front but the rear is the same.

Good luck!

Rocket Man · Oct 12, 2020

crabbman said:
thank you rocket man. not sure what you mean i can control the rear from the front. HERE ARE MY CONTROL KNOBS. LET ME KNOW HOW TO OPERATE THESE KNOBS?
thank you.

I see you only have the one control for the rear. My Denali has a second control that the rear passengers can access. The forward one can be set to control the rear HVAC or set so its controlled from the rear control head.

crabbman · Oct 12, 2020

thank you this helps. tomorrow i will start at the blower motor. look at it first, then maybe go to oreillys for the resistor.. if i can get the blower to run i feel the actuator doors will be much easier to fix or not to fix.
will update later tomorrow. thank you.

Fless · Oct 12, 2020

If you have questions about how the controls work, go to GM's web site and download the owner's manual. Free.

crabbman · Oct 12, 2020

thank you Fless. this helps.

crabbman · Oct 13, 2020

WENT TO OREILLYS. WAS TOLD TO DO MULTI-METER TEST FOR CONTINUITY. CHECKED ALL WIRES AND CONNECTORS. THE SCREEN NEVER CHANGED ON ALL MY PROBING. SO I FEEL CONFIDENT TO ORDER THE RESISTOR AT $104.76. OUCH!
I HAVE TO WAIT FOR THE RESISTOR IS IN GRAND JUNCTION. TOMORROW PRAY FOR CONECTIVITY WITH HOT AND COLD RUNNING AIR!
IT WAS ACTUALLY FUN TAKING OFF ALL THE PLASTIC SHROUDS AND LOOKING AT THIS GREAT DESIGN FOR A A/C MACHINE.

S33k3r · Oct 14, 2020

crabbman said:
WENT TO OREILLYS. WAS TOLD TO DO MULTI-METER TEST FOR CONTINUITY. CHECKED ALL WIRES AND CONNECTORS. THE SCREEN NEVER CHANGED ON ALL MY PROBING. SO I FEEL CONFIDENT TO ORDER THE RESISTOR AT $104.76. OUCH!
I HAVE TO WAIT FOR THE RESISTOR IS IN GRAND JUNCTION. TOMORROW PRAY FOR CONECTIVITY WITH HOT AND COLD RUNNING AIR!
IT WAS ACTUALLY FUN TAKING OFF ALL THE PLASTIC SHROUDS AND LOOKING AT THIS GREAT DESIGN FOR A A/C MACHINE.

Excellent. Hope this fixes the problem for you. That said, you might want to turn your caps lock off. All capital letters means you are shouting on the internet. It is okay for EMPHASIS, but if the whole thing is capitalized, it tends to make people not take your posts seriously.

Good luck!

MikeW · Oct 15, 2020

I have an 2002 Tahoe and had the same problem for almost a year....chasing fuses, blower direction valves etc - turned out to be rear blower motor - that's it!

crabbman · Oct 15, 2020

Thank you Mike w. You got lucky just like me. I went with the symptoms i first got that my daughter told me. i then poked at all wires and connectors from the resistor to the blower motor with my Multi meter.
The screen never changed. This gave me the confidence to pay Oriellys $104.76 for a new resistor. took just a few minutes to plug in, went up front to turn on ignition,no motor, and Wow the blower motor was loud and blowing very strong air. Wow this really blew my mind, so satisfying!

crabbman · Oct 15, 2020

S33k3r said:
Excellent. Hope this fixes the problem for you. That said, you might want to turn your caps lock off. All capital letters means you are shouting on the internet. It is okay for EMPHASIS, but if the whole thing is capitalized, it tends to make people not take your posts seriously.

Good luck!

Thank you Sir!.
i grew up with a keyboard with a green light for Cap letters and numbers. I no longer have that light to guide me. in fact i cannot find a keyboard with a cap lock green light anywhere on the internet. So sorry i am still struggling with this issue

Diagnose-No Power/No Air Flowing In Rear Vents

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