01' Tahoe and cabin heat

[stomachmonkey]

So last week the temp dropped from 85 to 45 here in TX.

Was driving the wifes Tahoe.

Surprise, no heat, just blowing cold air.

First thought is heater core so next morning I start it up and get it warm. In/out lines are roughly the same temp. Turn on blower and out line cools. So rule out heater core for now.

Climb under dash and locate one blend door motor, does not seem functional. Pull motor off blend door shaft and run thru combinations on the control panel and don't see the any movement of the motor. Manually operate the blend door, get a difference in volume but not heat.

There is a second blend door motor higher up that is a biotch to get to. Has one output shaft that actuates two cams, one cam for defrost which I can get to blow, the other for A/C. It's possible that there is an issue with the AC blend door but since both cams are driven from the same motor I'm skeptical that's the issue.

System is all electronic, no cables so it's possible the computer needs to be reset. Not an uncommon problem from what I understand.

So Monday while getting my morning coffee I bump into a tech from the Chevy dealer next door. Explain the situation and he says it sounds like the computer.

So here is my real question.

The tech suggests disconnecting the battery terminals and holding +/- leads together for 10 seconds to reset.

I'm hesitant to try that. Could be the guy gave me solid advice or could be he was annoyed by my seeking free advice and gave me a line of chit.

Thoughts?

[Dantilla]

I've got the factory service manuals for '01 Chevy trucks around here somewhere. I could take a look and see if there is a troubleshooting guide for the HVAC system.

[stomachmonkey]

Originally Posted by Dantilla

I've got the factory service manuals for '01 Chevy trucks around here somewhere. I could take a look and see if there is a troubleshooting guide for the HVAC system.

Would appreciate it.

It's a Dual Zone system so slightly different from the single zone.

Upper blend door motor is in the center of this image, two screws come out of it.



Lower apparently non functional motor is #9 in this pick.

[kaisen]

Very common. A good friend in Houston just had to do the EXACT same thing on his 2002 Suburban I helped him buy in 2003.

[stomachmonkey]

Originally Posted by kaisen

Very common. A good friend in Houston just had to do the EXACT same thing on his 2002 Suburban I helped him buy in 2003.

Reset the computer by touching +/- leads together?

[yetibone]

You can unhook both sides of the battery and touch the leads together safely. Be sure to unhook the negative side first or else the computer can be damaged by a current spike from the battery. All this does is completely discharge any residual power from the electrical system, which can make the computer forget any learned adaptive settings. You'll need a GM Tech2 scan tool to actually reset anything.

[stomachmonkey]

Originally Posted by yetibone

You can unhook both sides of the battery and touch the leads together safely. Be sure to unhook the negative side first or else the computer can be damaged by a current spike from the battery. All this does is completely discharge any residual power from the electrical system, which can make the computer forget any learned adaptive settings. You'll need a GM Tech2 scan tool to actually reset anything.

Gotcha.

Thanks

[pete3799]

Don't know if this will help but my Toyota pick-up did the same thing. Started it up and no heat. Top radiator hose hot,bottom cold,hoses to heater cold. Put a timing belt,water pump,
and thermostat in and now have heat.

[stomachmonkey]

Originally Posted by pete3799

Don't know if this will help but my Toyota pick-up did the same thing. Started it up and no heat. Top radiator hose hot,bottom cold,hoses to heater cold. Put a timing belt,water pump,
and thermostat in and now have heat.

I don't think it's an issue of getting hot water into the system.

It's a dual zone so has two separate systems fed from the same source.

Rear system is fine.

Could be the front heater core but doubtful. Usually when they go they start to leak inside the cabin and you'll smell the coolant.

Modern vehicles run/cycle hot water thru the core continuously regardless of whether you are on heat or A/C so the heater cores don't tend to rot like on older cars.

[yetibone]

Does an '01 have cabin air filters? I had an '04 2500 in with no heat recently. One filter looked like a miniature corn field.

[stomachmonkey]

Originally Posted by yetibone

Does an '01 have cabin air filters? I had an '04 2500 in with no heat recently. One filter looked like a miniature corn field.

Yes, caught a peak of it when I dropped what I believe was the pollen sensor.

Looked clean enough but will check properly.

[Oh Haha]

You would still feel heat with clogged pollen filter(s) but you wouldn't get any volume.

I don't know that this is your problem but I thought you might want to read it.
2000 Chevy Tahoe Heat issues

[kaisen]

Originally Posted by stomachmonkey

Reset the computer by touching +/- leads together?

No, replace the blend door assembly

Wayne, that thread is for a 2000 Tahoe Z71, which is the OLD bodystyle. Different animal.

[Oh Haha]

Originally Posted by kaisen

No, replace the blend door assembly

Wayne, that thread is for a 2000 Tahoe Z71, which is the OLD bodystyle. Different animal.

Sorry about that.

[stomachmonkey]

So was going to work on it today.

Wife had to drop of our daughter early this AM for a extracurricular activity.

Gets home and says "heat works"

Must have been a calibration issue that sorted itself out.

Go figure.

BTW, I had posted about this on a huge Chevy forum. Got more responses here in the first 2 hours than I did there in a week.

[speeder]

That's because we rock, Scott.

[Oh Haha]

Originally Posted by speeder

That's because we rock, Scott.

+1


Ok my suggestion was wrong but I still tried.