Hot air coming in cab??

[Logan]

Hey guys, I have a weird issue. First off my blower motor has stopped but I am gonna work on that issue. My big question/problem is that I have hot air coming out of the vents even when the HVAC control is in the off position. The blend door is actuating because when I move the control from off through AC to Heat I hear it in the dash so the vacuum part of the system works but when the HVAC is in the off postion I have hot air coming from the floor vents, like a pretty good amount.

Any ideas?

Also if I move the HVAC control to AC the hot air comes out of the vents, if I put it on defrost it comes out of the defrost but the blower motor is not engaged so it is air that is just kinda moving or radiating out.

 

[JAY]

Re: Hot air coming in cab??

There is no coolant control on these trucks like newer vehicles. Hot coolant will always be circulating the heater core even in the off position. You can always add a valve on the hose that runs to the core. In the winter, I run the heater for a bit than shut off the switch & am still able to maintain heat in the cab with it turned off.

 

[Logan]

Re: Hot air coming in cab??

I have another S10 and it doesn't act the same way. It is a pretty significant amount of hot air. Its like there is a fresh air leak that sends air over the heater core and through the ducting. Idk. I may just have to live with it but it doesn't seem right.

 

[ty166]

Re: Hot air coming in cab??

Maybe you have a damper door not functioning properly.

 

[Logan]

Re: Hot air coming in cab??

I figure I'll have to tear into it and see what's up. I just wondered if anyone else ever experienced a similar issue.

 

[TYRODD]

In my experience, that problem is caused by either a vac. leak behind the HVAC control or the cable becoming detached behind the control-the red cable retainer pops out.

 

[Logan]

Re: Hot air coming in cab??

In my experience, that problem is caused by either a vac. leak behind the HVAC control or the cable becoming detached behind the control-the red cable retainer pops out.

Awesome. Thank you for that. I'll check that and see.

 

[alwayscode390]

Re: Hot air coming in cab??

I just noticed this in my Syclone yesterday and came to ask about it.

Mine is hot if I have the setting to the hottest temperature on the dash ... but gets cool like the outside air temperature if I set it to the coolest setting on the dash.

Its coming out of the air vents near the transmission tunnel directly under the dash (near the firewall).

I thought my Transmission was getting overly hot when I figured out where it was coming from.

In my situation, its vehicle speed specific. If I am moving on the highway its more air, if I am stopped I cant feel it.

I am thinking this is normal like Jay said.

If I turn on my a/c its cold air , and my heater ... its even hotter air ( out the actual dash area, not the vents on the floor ).

If you find something, post it up and let me know ... thanks ! ---

 

[killa66cam]

Re: Hot air coming in cab??

I have always had this problem with any GM truck that I have owned...'86 S10, '95 Tahoe, '84 S10, '93 Ty, '04 S10. Think that this is a very common issue. I usually leave it at the coldest setting, or turn it to the middle to try and balance out the temperature.

Cam

 

[Logan]

Re: Hot air coming in cab??

I have just learned to live with it. I am chasing so many problems right now. But my 92 S10 doesn't seem to do it but I have learned that you dont poke the bear so until the engine and everything is dialed in on the Ty I don't care about a little hot air. Now in a few months I will probably not be able to control my OCD and have to fix it somehow.

 

[SY2932]

Re: Hot air coming in cab??

The most probable cause can be seen here. Sounds to me like the cable to your blend door has become disconnected. Super easy fix...