'06 TB has no heat al all. Brrrrrr, and I'm only in Georgia.

[rwf]

Well here goes my first "question" post, hope I picked the correct section.

I am trying to diagnose a really stubborn heat problem on my 06 Trailblazer. There's no heat at all, ever. I got in March with 28K miles on it and although I thought I tested everything, I forgot the heat. :-(

Took it to dealer, who saw me coming and charges me 50.00 to tell me the coolant was empty (it wasn't just a little low from a hose leak. Later I took it to a shop, who kept it for a week while I was out of town. First they said the core was blocked, but they say they flushed it out. They say that that both hoses are warm (I haven't ever seen the hoses nor do I know where to look. All I see are A/C hoses under the hood.)Then they decided it was a temperature control valve under the washer reservoir, but I never saw such a valve. Then they abandoned that theory and said they snaked out some bypass tube sort of behind the engine, that it was clogged. Now they want to remove the dash and check the damper doors, etc. They are sure that's it. I don't really have any more time to leave it there and I am not sure they are that familiar with the system and may be grasping at straws.


I have read a lot of threads about heat issues but they all seem to do with things like heat but no cool or cool but no heat on one side or the other. But I haven't been able to locate a problem such as mine.

I got under the dash and looked for the actuators and I don't see than at all. I only see ductwork. I looked from under the driver's dash with the side panel of the console folded back. I looked in the same places on the passenger side. I just can't see any of the guts of the system at all.

I'm really at a loss here. I don't want to go to the dealer because they have done me wrong twice in the last 6 months and I think that I should be able to fix this. I just don't know the system.

Can anyone point me in the right direction or give their thoughts?

Thank you so much in an advance!

 

[C-ya]

Welcome! Here's the link to get the shop manuals for your vehicle - http://gmtnation.com/f23/need-service-manuals-get-them-here-371/

I would think it is the heater control valve if you have no heat anywhere, or the core really is blocked. You could feel the hoses coming off the manifold/head and see if they are warm. Find a friend or relative is familiar with cars in general (or look in the book) and learn what hoses do what. Feel the hoses for heat after the truck has been running and the controls are set to "heat" inside. Find the A/C compressor and follow those hoses so you know which ones they aren't.

Good luck with it. It gets cold enough in GA! My parents live near Gainesville, so I know it can get chilly.

Just had a thought - does your rear heat work at all? As in is it warm?

 

[rwf]

Thanks for the response.
I got the manuals a while back.
And I didn't mean to come across as a noob. I have been servicing cars since my 68 Nova back in High School.

Its just that I am not that familiar with the TB HVAC because I just got it and it has had so many issues already to fix:
*Fan clutch,
*driver door module intermittent,
*fan blade disintegrating and sending pieces flying through the washer reservoir and a radiator hole,
*stupid 20" lo pro tires that were on it- while trying to locate some factory rims to put on in stead of the ghetto 20"s, the tread separated on the RF tire and tore up my bumper cover, LF fender and liner so now I have to change all that).

And this is all on a 32K mile truck!

Y'know normally the heater hoses are pretty evident, especially where they go through the firewall, but because these newer cars seem to have sort of a "pod" in the center where all the main stuff is (radio, HVAC, etc) that I guess the hoses must be mostly behind the engine.

I do not have heat (or warmth) in the rear system either. From what I understand part of the rear system comes from the front system and part is from another HVAC unit in the right rear. Its pouring rain and I don't have a lift so I don't think I'm crawling under the right rear of the truck to find hoses today.

I took a look at some under dash diagrams Roadie posted helping someone else and those diagrams don't seem to match. Do you know if the heater control valve you speak of is in that HVAC pod or would it be under the hood?

Thanks again, and I am eagerly awaiting any constructive input.

Welcome! Here's the link to get the shop manuals for your vehicle - http://gmtnation.com/f23/need-service-manuals-get-them-here-371/

I would think it is the heater control valve if you have no heat anywhere, or the core really is blocked. You could feel the hoses coming off the manifold/head and see if they are warm. Find a friend or relative is familiar with cars in general (or look in the book) and learn what hoses do what. Feel the hoses for heat after the truck has been running and the controls are set to "heat" inside. Find the A/C compressor and follow those hoses so you know which ones they aren't.

Good luck with it. It gets cold enough in GA! My parents live near Gainesville, so I know it can get chilly.

Just had a thought - does your rear heat work at all? As in is it warm?

 

[The_Roadie]

Welcome. Boy, you have a mess of issues, but perhaps you can start by fixing the engine type in your profile.

The diagram I've posted many times is the "pod" as you call it. The five actuators are there somewhere. Here's a pic of my dash removed.

The hoses through the firewall are on the passenger side near the AC receiver/drier and the adjacent AC hoses.

The rear HVAC unit on the EXT has a separate blower motor, its own temp actuator, and its own airflow mode (floor/ceiling) actuator. It also has its own heater core and AC condenser. And Looooooong hoses for both heat and AC from the engine compartment running down near the frame.

What's your coolant temp? Does your gauge indicate straight-up 210 degrees as it should?

 

[rwf]

Thanks Roadie!
That dash removal looks scary. Thank you so much for the picture. I'm going to enlarge it and look for the various items.
And I will attend to the engine type in the profile. I guess I chose the wrong version of 6 cylinder lol.
It does have a lot of issues, and I realize now I said the Rt Front tire separated and messed up the left front fender. Of course it was the Left front tire.
So much damage from one tread coming off- it looks like I was in a big wreck on the left front.

The engine temp is 210 and it gets there pretty soon after starting up. Do the rear hoses tee off the front ones or do they come off the engine somewhere?
I want to get underneath and feel them but it is still pouring and I don't have a functional garage in which to work.

Welcome. Boy, you have a mess of issues, but perhaps you can start by fixing the engine type in your profile.

The diagram I've posted many times is the "pod" as you call it. The five actuators are there somewhere. Here's a pic of my dash removed.

The hoses through the firewall are on the passenger side near the AC receiver/drier and the adjacent AC hoses.

The rear HVAC unit on the EXT has a separate blower motor, its own temp actuator, and its own airflow mode (floor/ceiling) actuator. It also has its own heater core and AC condenser. And Looooooong hoses for both heat and AC from the engine compartment running down near the frame.

What's your coolant temp? Does your gauge indicate straight-up 210 degrees as it should?

 

[rwf]

Well I found and traced the heater and A/C hoses/pipes from the rear to the front and lost them once they came up between the master cylinder and the engine. The heater hoses weren't warm so I'm not sure exactly what that means yet. I found where the hoses//pipes for the front unit go through the firewall and also found this horizontal cylindrical part mounted to the firewall. For some reason this vehicle routes wires, pipes, and hoses all over the place and it is much more difficult to figure out then thr '95 Tahoe it replaced!

I'm wondering if this is some sort of cut off valve for the heater water and if that maybe is my culprit. Do you guys know what this thing is? and maybe a suggestion of how to bypass it if it is hot water related? It has a 2 conductor plug on it.

View attachment 25497

 

[MAY03LT]

I found where the hoses//pipes for the front unit go through the firewall

The metal lines that you can barely see in your pic are for the A/C. The other ones are for the heater core. If neither of the heater core lines are hot (and I mean really hot) next thing I would do is see if the radiator hoses are getting hot.

I'm wondering if this is some sort of cut off valve for the heater water and if that maybe is my culprit. Do you guys know what this thing is?

At the risk of sounding like an EXT-noob (which I am), IIRC it's an auxiliary pump to help push coolant to the rear heater core.

 

[rwf]

Thank you for the reply. I had read that there was an aux pump added on some models but was somehow envisioning it would be inside the cabin. No reason, its just what I thought. I think the radiator hoses are both getting plenty hot, and I just had the water pump, thermostat and hoses replaced.

I wonder if maybe I should loosen one of the heater lines going to the front core (or that little pump) and just see if I can manage to get scalded. Then I will know that there is at least hot water.

I am pondering over the service manuals available on the site here, but the 2006 one is really just a bunch of diagrams and doesn't seem to have the service info that the 2002-2005 set has. So I'm using those as a guide. I don't really know what changed much, though.

This is so perplexing because now I want to believe that there is no hot water supply to either core and I guess the only thing they have in common is the engine block. I want to believe the shop that had it a week who told me the core was getting hot and that they flushed it, but things just aren't adding up in my opinion.

The metal lines that you can barely see in your pic are for the A/C. The other ones are for the heater core. If neither of the heater core lines are hot (and I mean really hot) next thing I would do is see if the radiator hoses are getting hot.



At the risk of sounding like an EXT-noob (which I am), IIRC it's an auxiliary pump to help push coolant to the rear heater core.

 

[AV8ER]

I don't know if this will help but I'm pretty sure the rear heat lines run along the inside of the frame under the drivers seat. I know they are rear HVAC related and when I touched them the other day I about burned my hand. I will take pics tomorrow to show which I am talking about