Looked under the dash of the Tahoe tonight

[Camino LS6]

...kinda wish I hadn't.

It has HVAC issues, and everything is electrical.

I may actually pay someone else to figure it out...

Edited October 27, 2010 by Camino LS6

[ocnblu]

Still no sign of Jimmy Hoffa, eh?

Good luck with it, you're gonna need to clear the windshield here shortly when frost hits.

[Intrepidation]

Get a dash harness from another one. Swap the whole thing out.

[Camino LS6]

Thanks, Ocn.

Arkus is fogging up the winsheild when he rides with me on these rainy days, so yeah, it has to be dealt with.

HVAC systems are another planet for me - especially all electric ones.

I may fiddle with it on sunday.

Get a dash harness from another one. Swap the whole thing out.

I don't think the harness is the problem. I think it is one of the control modules.

[ocnblu]

Oh I forgot about your living humidifiers. Yikes!

[Camino LS6]

Oh I forgot about your living humidifiers. Yikes!

LOL

Arkus is the only one that causes trouble since he insists on sticking his nose right up to the windsheild - Zora just sits in the back like a good dog.

[daves87rs]

Oh I forgot about your living humidifiers. Yikes!

Lol...

[Camino LS6]

I think I'll dig into the upper dash/IP before anything else - the previous owner was a hack and put in an aftermarket stereo (that barely functions). I want to make sure he didn't screw-up the connections at the HVAC controls.

[Drew Dowdell]

you have the service manual?

[Camino LS6]

Unfortunately, no.

[balthazar]

What is the specific issue?

[Camino LS6]

At the moment it has no heat (separate issue), and air is not being re-directed to the defroster vents.

[Camino LS6]

I picked-up a new radiator, heater control valve, and A/C relay today.

On a whim, I checked the fuse/relay block under the hood and the A/C relay was missing. I found it in the pocket of the driver door and plugged it back in. I now seem to have some air coming out of the defroster vents.

Now, someone has rigged the relay with a bare wire bridge between two of its terminals for some reason - so I bought a new one. I'm about to see what that does for me.

The heater control valve has been suspect from day one so I bought that too.

And, I know that the radiator is leaking so both are on my agenda for Sunday (or sooner if I get inspired).

[Camino LS6]

Dug into the dash and removed the aftermarket stereo.

I think the HVAC controls could have been damaged when it was put in. The housing is broken on one side for sure, but I'll have to get it out of the dash to have a look at the back.

[A Horse With No Name]

Keep us posted, and good luck....

[Camino LS6]

Gave it a really good flushing, a major cleaning, replaced the radiator and heater control valve, but still have HVAC troubles.

And now the power windows are fried.

At least it's running nice and cool now.

[Camino LS6]

...and now the other shoe drops!

The Tahoe is now sucking coolant bigtime. It's either leaking through the manifold (bad), or it blew a head gasket (worse).

[Drew Dowdell]

coming out the exhaust?

[Camino LS6]

Yes, in a massive cloud.

[Camino LS6]

I may try Bars-leak as a temporary fix...

Ripping apart the engine just doesn't fit my gameplan at the moment.

[Drew Dowdell]

I may try Bars-leak as a temporary fix...

Ripping apart the engine just doesn't fit my gameplan at the moment.

That's probably what you flushed out of there in the first place....

[Camino LS6]

That thought had crossed my mind.

The old cap didn't quite fit the new radiator, so I installed a new one - that's when the cloud started.

I'm going to try the Bars-leak, and hope I can put-off any further repair until after the winter.

Wish me luck.

Edited October 13, 2010 by Camino LS6

[Camino LS6]

Stuff seems to ne working - knock wood.

I ordered a new power window master switch today, hopefully that problem will be gone tomorrow.

Then it will be back to the HVAC issues.

[Camino LS6]

It was an expensive switch, but it did the trick.

My windows work again.

[Drew Dowdell]

camino, you ever ordering these parts from advance auto? if you do, mind clicking a link on C&G before you order it? We'll get a kick back

[Camino LS6]

camino, you ever ordering these parts from advance auto? if you do, mind clicking a link on C&G before you order it? We'll get a kick back

Actually, I've never even seen an Advance Auto store around here. I priced the part at NAPA, but actually got a better deal from GM. I get a pretty good discount, so I saved about $40 going with genuine GM.

[Camino LS6]

OK, I no sooner got the windows working and the driver's door handle broke!

So, I left another 80-some dollars at the chevy place today for a new handle and 2 levers that were missing from the HVAC system under the dash.

The previous owner is climbing higher on my hate list.

I installed the new handle and the levers, but still don't have adequate heat and defrost.

This is getting frustrating.

[A Horse With No Name]

Odd...one would think the HVAC system would be simple enough to repair....sorry to hear that you are having problems.

[Camino LS6]

It's actually fairly complex and very tough to get to.

But the biggest problem is that the previous owner screwed things up quite a bit. I'm just fixing each problem as I identify it, at this point I don't know if the heater control panel is at fault or the actuators. But the air doors are not doing what they should be doing and I am not getting enough heat in the system. The blower motor also stops now and then for no good reason.

[A Horse With No Name]

You might try a couple of things, Camino. First of all, you might use NO-Lox on the connection to the motor, after you clean the connection.. It will keep moisture and corrosion out of the connection, and ensure that it isn't corrupted in the future.

IF one of the ducts isn't collapsed, I'd bet you are not getting enough RPM's out of the motor, or tht an old motor doesn't have enough torque to turn the blower wheel at the proper speed.

Only three variables exist, or perhaps 3.

1. Electrical conditions at connections to motor.

2. Condition of motor and it's ability to do the job.

3. Lack of obstruction in the ductwork

4. Control of any subsequent adjustment devices (doors, louvers, etc.)

At least this is the way I would see it....

If your serious about keeping the vehicle, would it not be easier to pull the dashboard itself to check the problem?

I actually have had animals build nests in ductwork (including rattlesnakes!). I wonder if a couple of fornicating mice might have gotten a little too comfortable and trapped in there somewhere?

[Camino LS6]

Thanks for the input.

-The blower motor problem is likely to be the resistor - known issue with these.

-Most of the problems stem from the hack previous owner installing a "system", and then removing it.

-I've pulled various bits of dashboard and HVAC casing, with no sign of obstructions.

-This syatem has at least three electric actuators for the air doors and I don't know if two of them work at all.

-At least 1 of the air doors doesn't move regardless of the position of the knob on the controller. The other two doors move a little bit (there may be more doors too).

- My main suspect is the control panel (a very expensive part).The plastic housing has been damaged for sure, and I suspect the circuit board to be bad.

-The previous owner claimed to have "just replaced" the heater core (and it does look new), but I don't know what else he screwed up. Considering that he removed to of the levers that connect the actuator to two of the air doors (I replaced them today), anything is possible.

[Camino LS6]

I think I'm just going to bite the bullet and get a new control panel.

Even if the old one is ok, the mounting tabs are broken off and it's loose in the dash.

$250

But it will take that variable out of play.

[SAmadei]

I think I'm just going to bite the bullet and get a new control panel.

Even if the old one is ok, the mounting tabs are broken off and it's loose in the dash.

$250

But it will take that variable out of play.

$250?

That sounds like a trip to the pick-a-part. Most HVAC control panels hold up and there should be lots to pick from for cheap.

[Camino LS6]

This area is pretty weak on pick-a-parts.

[SAmadei]

This area is pretty weak on pick-a-parts.

Do you have a photo of the faceplate? I forget what year your Tahoe is. The two decent Pick-a-Part places near me had quite a few '90s GM trucks, I wouldn't mind taking a walk about. Any special tools needed to get the unit out, besides a T15?

[Camino LS6]

Thanks for the offer, Samadei.

But I need to get this done - yesterday.

My Tahoe is a '95, and the controller panel is a one-year-only part.

Figures, right?

The mounting is really simple ( if a bit weak). The unit just clips into the dash framework with plastic tabs - unfortunately, they are prone to be brittle and easy to break. The main I/P surround has to be popped-off to get access.

Just drove it through the rain and could barely see where I was going, so I'm going to try to make this happen today.

[A Horse With No Name]

Good luck, wish I was in Philly with the day off so I could help you, sir.

Sounds like the problem is the $250 part. I'm impressed that its still available.

In Commercial HVAC, solving air flow problems often takes care of issues. However, 95% of what I see in buildings is caused by an electrical malfunction, so...I think your on the right track...

[Camino LS6]

I wish you were around too!

I could use an assist with this one.

Good to know that your thinking concurs with mine - let's hope we are right.

I'll report the results either way.

[A Horse With No Name]

"http://failblog.org/2010/10/18/epic-fail-photos-tailgate-grill-fail/"][/url]

Just do what the Toyota owner above did, you will have heat in no time!

Edited October 19, 2010 by 66Stang

[Camino LS6]

Not so sure I like that solution...

'sides which, my rear defrost works!

[Camino LS6]

SUCCESS!

Well, at least to a point.

I now have airflow where, and when I should. That gold-plated control panel did the trick.

Now I have just the lack of enough hot coolant flowing through the heater core (which may correct itself with some miles), and the intermittent behaviour of the fan motor (likely the resistor).

So,

-windows work

-door handle works

-heat and defrost work to a point

- new radiator is doing its job

Getting there now.

[Drew Dowdell]

Did you burp your baby?

[Robert Hall]

Hmmm..not sure if the GM truck HVAC setup is similar, but I recall a number of years ago my Mom's '96 Explorer had a faulty damper door aka temperature blend door...blocked heat from coming out of the heater core. Was getting no heat or defrost functionality.

Was an expensive fix IIRC, had to remove a lot of the dash to get to it..

Edited October 19, 2010 by Cubical-aka-Moltar

[Camino LS6]

Did you burp your baby?

Repeatedly.

[Camino LS6]

Hmmm..not sure if the GM truck HVAC setup is similar, but I recall a number of years ago my Mom's '96 Explorer had a faulty damper door aka temperature blend door...blocked heat from coming out of the heater core. Was getting no heat or defrost functionality.

Was an expensive fix IIRC, had to remove a lot of the dash to get to it..

The new control panel seems to have brought all of the doors back to full functionality.

The heat issue may be crud in the heater core, I suspect that the previous owner didn't flush all of the Dexcool out before he used the green stuff. The heat level is improving now.

The last major problem is either the blower motor and/or the resistor.

[A Horse With No Name]

Replace them both, and then enjoy the Tahoe for the next ten years.

$250 is half of what a new truck payment would be, and you don't have 28K hanging over your head in the form of a bank loan. Consider yourself lucky!

[Camino LS6]

True.

Ordered the blower motor today.

[A Horse With No Name]

Should be a neat truck when you get her sorted out.

It was the last truck, the manual shot one, that had the weird rust problems around the tail gate, right?

[Camino LS6]

Yeah, the Blazer.

I really liked that one.

I think I posted one pic of this Tahoe here. It's green with barn doors.

[A Horse With No Name]

That's a nice looking truck!