AC left me hanging

[Dustin Jackson]

Got in my Tahoe after work yesterday and was about to start driving when I noticed my AC wasn't working, not blowing any air at all.

I messed with that controls (temp controlled dual climate controls) a bit and accepted defeat and began my drive home in 95F+ heat with the windows rolled down.

Shortly into the drive my AC started working again, I don't know if I hit a bump or something or if my cabin temp sensor would cause the AC to not active?

It happened once so I am sure it will happen again, I want to see what y'all know about about these AC systems so that I am prepared next time this happens.

 

[Trey Hardy]

Hmm that’s weird bud. Do you think it came from the actual ac controls itself? My rear console ac control went bad and caused the rear not to work and I had to replace the module/ac control to fix it.

 

[Dustin Jackson]

@Trey Hardy Thats what I’m thinking. In my Tahoe to set max AC you need to set the temp to 60F, with “auto” on, recirculation on, and the snow flake on. And that’s how I had it set but no air was moving. I started driving and suddenly the air started blasting Ice cold as usual about 120 second after starting it.

 

[Dustin Jackson]

I think it could be the cabin air temp sensor because the heater doesn’t work unless I set it to max heat 80 or 90F can’t remember exactly. That clues me to think the the climate system can’t really tell the temp of the cabin

 

[Trey Hardy]

I think it could be the cabin air temp sensor because the heater doesn’t work unless I set it to max heat 80 or 90F can’t remember exactly. That clues me to think the the climate system can’t really tell the temp of the cabin

That also sounds like a likely culprit I diddnt even realize there was a cabin temp sensor I’ve only replaced everything else under the sun (rear control module,front door and blend actuators, compressor and condenser, and one other thing I forgot the name of it) everything BUT the temp sensor lmao
I’ve never put mine in auto either it’s straight to 60 and full blast with recirculation on and that’s where she stays

 

[Dustin Jackson]

@Trey Hardy I think there a couple of them so I don't want to replace the wrong one. I am going to do some research about a failing cabin air temp sensor

 

[Dustin Jackson]

Update: Today is the first day that the AC didn't turn on for me since the last time I posted but today lasted almost the whole ride home. I took a video of what was happening. Things to note, the rear HVAC seems to work just fine when the front isn't working.

Usually when I get in my Tahoe and turn on the AC I can hear the servos in the dashboard moving but when this problem is happening there is no sound from the dashboard, like it's not even trying to run.

When driving I can feel cool air coming from the vents so I know the compressor is working, but the front blower and the servos do not work while this problem is present.

Any ideas?

 

[Dustin Jackson]

After some research it seems to be the blower motor resistor. I went out and unplugged it and it has the same symptoms that were happening earlier today. Anyone else agree or am I off in the weeds?

 

[89Suburban]

Good teamwork guys keep at it. Wish I knew more to contribute.

 

[swathdiver]

Tech-2 time Dustin.

 

[Dustin Jackson]

@swathdiver Because of recent events I need to invest in home security. My budget for that is already less than $100… also just did my brakes.

How much is one of those bootleg tech2?

 

[swathdiver]

@swathdiver Because of recent events I need to invest in home security. My budget for that is already less than $100… also just did my brakes.

How much is one of those bootleg tech2?

They've been around $300 shipped. Curiously, they are not listed on ChinaCarDiags tonight, neither is the MDI2 I've been waiting for!

VXDiag Nano or similar is about $120 and works off laptop with bootleg GDS software.

Check out the Tech-2 owner's map and see who lives near you that has one. If they're on the list, they'd be happy to help. Don't think you're in Florida, if so, stop on by!

 

[Dustin Jackson]

@swathdiver Haha I appreciate that man. I’ll hit up the local car and off-road groups and see if they have one.

What do I tell them I’m looking to do here with the tech2? How will that help here?

 

[swathdiver]

@swathdiver Haha I appreciate that man. I’ll hit up the local car and off-road groups and see if they have one.

What do I tell them I’m looking to do here with the tech2? How will that help here?

For starters you'll want to view the internal trouble codes in the BCM for the problems you are having. Then you can move on to diagnostics, manipulating the actuators and output speed of the blower motor, check that the aspirator in the headliner is still working, etc.

Worst case your control module is going out and a new one would have to be programmed to the vehicle. A used one should work if the donor has the same options as yours HVAC wise.

 

[Dustin Jackson]

Happened again today, i reached over and smacked the bottom of the passenger dash where the blower and resister are at. The air started blowing immediately.

I read somewhere that there is a known problem with the blower motor resistor connector getting melted so I will look into this

 

[Dustin Jackson]

Update:

The blower for the front of the Tahoe quit entirely last week. Leading up to complete failure the front air blower would pulsate a bit before turning on all the way.

$50 later from Orileys I have a janky new blower resistor installed and now the front blower works again.

I would have preferred to grab an original blower resistor from the junk yard but they didn’t have any trucks as new as these there.

Problem fixed.

 

[Dustin Jackson]

This morning it was cold the blower wasn't working again. I reached over and smacked under the passenger dashboard and the blower came on again...

I am going to put the old resistor back in and see if I can get it to work at all and do a better job of inspecting the electrical connectors.

Can't drive if I can't see in the morning..

 

[Dustin Jackson]

I am going to try some of the troubleshooting steps in this video, around 5:40 it gets good

 

[mikez71]

Great video! Hope that's it!

I was guessing blower motor, but that video changed my mind...

 

[Dustin Jackson]

Today there was a twist in my troubleshooting

This morning I had more issues, I smacked the lower dash and the blower came on just fine. After lunch I removed the under dash cover to started digging into troubleshooting and I could not get the blower motor to work regardless of what I did. Wiggling the wires or smacking it did not do a thing.

I inspected the wires carefully and none smelled or looked burnt.

I wiggled the wires all over and the blower never came on.

I used a multimeter to trace voltage all the way up to blower motor which was confusing because the blower motor would totally work fine once it was on. It looks like if you smack the blower motor directly or give it a spin to get it to start it will turn.

I put the old blower resistor into the Tahoe and same behavior happened where I had to mess with the blower motor to get it to start.

Everything is pointing to the blower motor itself now.