Heat issue continues, maybe..

[akbrener]

I had posted an issue with my 2008 heat a few weeks ago and i have a feeling i still have an issue, but I am not 100% familiar with this Tahoe. I recently started driving daily as we traded my jeep to get my wife a new Tahoe.

This one has the dual zone digital HVAC, I have checked all the actuators and they function correctly. At idle and low speeds I will feel warm air starting around 76* selected on both front and rear HVAC systems. from 75-90 I get warm air but on my 25 mile drive to work at interstate speed the heat will gradually taper away at around the halfway mark. This problem is on BOTH front and rear.

Does this system always sense the interior temperature through the aspirator in the headliner even if not in "AUTO" mode? Was thinking that it was adjusting to the interior temp.

I have checked all the actuators, they seem to move as designed, the doors all move freely... i have replaced the thermostat and flushed the coolant. and put a new cap on the coolant resivoir. No change.

Any chance the water pump may be on its way out? its a long shot, there is no sign of overheating or underheating, runs at the 210 mark... only thing i dont really get is a sign of pressure in the system if i pop the resivoir with it warm.

Maybe if the system is always sensing the temperature of the interior it just hasnt gotten cold enough yet? usually in the mid 50s on my morning drives.

Any input would be appreciated. thanks.

 

[Doubeleive]

It could be the aspirator in the headliner, they are only about $25 online so pretty easy to swap and find out, what you really need is a tech2, if the engine temp is normal then it would not be related to the engine coolant.

 

[akbrener]

Hmm.. so the temp sensors are active even if not in Auto mode? every now and then the one above my head starts to buzz on occasion. but thats intermittent.

does the tech 2 check the status of things, or is there maybe a hidden trouble code that I am not seeing on my Torque App?

 

[Doubeleive]

Hmm.. so the temp sensors are active even if not in Auto mode? every now and then the one above my head starts to buzz on occasion. but thats intermittent.

does the tech 2 check the status of things, or is there maybe a hidden trouble code that I am not seeing on my Torque App?

the tech2 can check and control all of it, the aspirator is not the only sensor my truck has 2 aspirators one in the front and one in the back. There is also around 6 temperature sensors inside the air duct's. I am not certain if it relies on the aspirator when not in auto mode. The Torque app will not read any trouble codes related to the hvac, mine had a bad actuator on the passenger side so it would blow cold air on the drivers side and luke warm air on the passenger side the only thing that would provide the error information was the tech2. I would imagine other very high end scanners would see it also like a snapon solus, etc but not your run of the mill code reader I even have a $350 innova which can do a lot of things but it still wont read bcm codes or control various functions, not even close to what the tech2 can do, apparently some trucks even have 3 aspirators I had replaced my control unit last summer and everything worked fine until is started to get cool and I needed heat, the front would work fine but the rear would blow cold unless it was set to 89 or 90, if you set it to 87 it would blow stone cold, the tech2 kept telling me there was a rear temp sensor error, so after tearing everything apart and a lot of troubleshooting I discovered the control unit was looking for a sensor that did not exist in my truck, so I had the dealer flash the control unit to my Vin and walla everything worked perfect again.

 

[akbrener]

Looks like the ceiling mount aspirator was an issue, heat appears to be more responsive at lower temp settings. still nothing in the back, but will order another aspirator and see how it goes. both were very dirty.

 

[karel k]

the tech2 can check and control all of it, the aspirator is not the only sensor my truck has 2 aspirators one in the front and one in the back. There is also around 6 temperature sensors inside the air duct's. I am not certain if it relies on the aspirator when not in auto mode. The Torque app will not read any trouble codes related to the hvac, mine had a bad actuator on the passenger side so it would blow cold air on the drivers side and luke warm air on the passenger side the only thing that would provide the error information was the tech2. I would imagine other very high end scanners would see it also like a snapon solus, etc but not your run of the mill code reader I even have a $350 innova which can do a lot of things but it still wont read bcm codes or control various functions, not even close to what the tech2 can do, apparently some trucks even have 3 aspirators I had replaced my control unit last summer and everything worked fine until is started to get cool and I needed heat, the front would work fine but the rear would blow cold unless it was set to 89 or 90, if you set it to 87 it would blow stone cold, the tech2 kept telling me there was a rear temp sensor error, so after tearing everything apart and a lot of troubleshooting I discovered the control unit was looking for a sensor that did not exist in my truck, so I had the dealer flash the control unit to my Vin and walla everything worked perfect again.

HI there - I am living in England and I think I have one of the few (if any) Chevy Tahoes in the country. It is a challenge sometimes to find some expertise for any uncommon issue, as you can imagine. Most of my parts I order from the US and have someone here install it.
I now have an issue that sounds very much like what you mentioned in a recent post : I have the dual zone HVAC (and rear AC) and now my passenger side is blowing cold air when I would expect hot air. I think I have a canadian version as the speedometer has KM's in it next to the Miles.
I hope you could help me with some advice where to locate the aspirator(s) to replace them , before tearing the whole dashboard up.
thanks for any suggestions !

Karel
[email protected]

ps - sorry if this is not the right way to get support , I could not find how to enter a new post somehow.

 

[wjburken]

HI there - I am living in England and I think I have one of the few (if any) Chevy Tahoes in the country. It is a challenge sometimes to find some expertise for any uncommon issue, as you can imagine. Most of my parts I order from the US and have someone here install it.
I now have an issue that sounds very much like what you mentioned in a recent post : I have the dual zone HVAC (and rear AC) and now my passenger side is blowing cold air when I would expect hot air. I think I have a canadian version as the speedometer has KM's in it next to the Miles.
I hope you could help me with some advice where to locate the aspirator(s) to replace them , before tearing the whole dashboard up.
thanks for any suggestions !

Karel
[email protected]

ps - sorry if this is not the right way to get support , I could not find how to enter a new post somehow.

Welcome to the forum from Iowa!

What year is your Tahoe? We like pictures here.

Are you still getting hot air on the driver side?

If you are just getting cold air on the passenger side but are still getting hot air on the driver side, it could be a blender door. They are pretty straight forward to replace but can be a challenge to get to.

 

[Doubeleive]

HI there - I am living in England and I think I have one of the few (if any) Chevy Tahoes in the country. It is a challenge sometimes to find some expertise for any uncommon issue, as you can imagine. Most of my parts I order from the US and have someone here install it.
I now have an issue that sounds very much like what you mentioned in a recent post : I have the dual zone HVAC (and rear AC) and now my passenger side is blowing cold air when I would expect hot air. I think I have a canadian version as the speedometer has KM's in it next to the Miles.
I hope you could help me with some advice where to locate the aspirator(s) to replace them , before tearing the whole dashboard up.
thanks for any suggestions !

Karel
[email protected]

ps - sorry if this is not the right way to get support , I could not find how to enter a new post somehow.

Please reference my youtube video for how to fix the passenger side blend door actuator

 

[OR VietVet]

HI there - I am living in England and I think I have one of the few (if any) Chevy Tahoes in the country. It is a challenge sometimes to find some expertise for any uncommon issue, as you can imagine. Most of my parts I order from the US and have someone here install it.
I now have an issue that sounds very much like what you mentioned in a recent post : I have the dual zone HVAC (and rear AC) and now my passenger side is blowing cold air when I would expect hot air. I think I have a canadian version as the speedometer has KM's in it next to the Miles.
I hope you could help me with some advice where to locate the aspirator(s) to replace them , before tearing the whole dashboard up.
thanks for any suggestions !

Karel
[email protected]

ps - sorry if this is not the right way to get support , I could not find how to enter a new post somehow.

Great place to start is always the Newbie section with an introduction and pics of your rig.

Welcome to the forum from Oregon.

 

[karel k]

Welcome to the forum from Iowa!

What year is your Tahoe? We like pictures here.

Are you still getting hot air on the driver side?

If you are just getting cold air on the passenger side but are still getting hot air on the driver side, it could be a blender door. They are pretty straight forward to replace but can be a challenge to get to.

HI - thanks for your reply - added a pic of my tahoe, it is a 2007 LTZ . Can see the license plate is from the Netherlands but I live in the UK.
I have had a look at what's accessible under the dash but indeed pretty hard to get at things.
Sounds like that could indeed be the issue, will have a go at it.