Heater Won't Turn Off Heat

willfxp · November 7, 2005

When I turn on my heater (moving the temp control from cold to hot), most of the time it will stay on hot even after I turn it back to cold. Not sure what to do. If I turn off the vent system completely (pushing the recirc button), sometimes after a while (an hour while the engine is still on) it'll go back cold.

When the engine is off for a while, it will go back to cold.

Any ideas? My guess is that some valve expands too much and gets stuck on, and the only way is stop the car (or the airflow) so it'll cool down and pop back into place?

My truck, 2001 Silverado 1500 LS/Z71. Thanks!

GM-Tech · November 7, 2005

Is it safe to assume this has driver/passenger temp controls? If so, do both sides do the same thing?

willfxp · November 7, 2005

There is only one setting for both. Thanks. "Old" style, one climate zone

SteveCZ · November 9, 2005

Mine does the same thing, If you listen carefully, can you hear the sound of something moving? Like if you switch from Vent to Defrost, it sounds like a motor turning slowly...

I'm wondering if its something up by the heater core that is stuck, I doubt its the Climate Control?

GM-Tech · November 9, 2005

There is only one setting for both. Thanks. "Old" style, one climate zone

I'm not really familiar with these. I think I've seen ONE. Our service information isn't really clear on this, but assuming it uses the same type of actuator as the dual zone system, I'd say it is probably the temp actuator.

What happens with these types of system is that when the control head can't determine the position of the door because of a faulty reading from the actuator, it forces the temp door to a default position, which happens to be the hot position.

willfxp · November 10, 2005

I'm not really familiar with these. I think I've seen ONE. Our service information isn't really clear on this, but assuming it uses the same type of actuator as the dual zone system, I'd say it is probably the temp actuator.

What happens with these types of system is that when the control head can't determine the position of the door because of a faulty reading from the actuator, it forces the temp door to a default position, which happens to be the hot position.

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So I just need to replace the temp actuator? Is that an easy job or something I'll need to bring to the dealer for? Thanks. Oh, and lately, I've been smelling a SLIGHT radiator fluid smell when the heater is on. Don't remember smelling that last winter.

SteveCZ · November 10, 2005

Will,

Good question, I'll be watching this topic so I can fix mine too..

SteveCZ

GM-Tech · November 10, 2005

So I just need to replace the temp actuator?

I can't tell you that and be sure that's what it is. It may be an actuator problem, but it could also be wiring, the control head itself, etc., etc. We have a hard enough time diagnosing some of these problems when the vehicle is right here in front of us. Trying to guess based on some comments over the internet is nearly impossible. I can only tell you what's common. If you want to throw that part at it, yeah, it may fix it.... or it may not.

trentw · April 4, 2006

Has anyone fixed this issue? I'm now experiencing the same thing in my 2001 Chevy Tahoe. The rear heat controls work properly but the front won't return to cool after it has been turned to max heat. Has anyone successfully fixed this on their own? Thanks.

Trent

SoCalChris · April 4, 2006

We had this problem on our 99 Safari. It was caused by a cracked vacuum line. The line that broke was run past the engine, so I think the heat made it brittle. Once I patched the vacuum line, it worked perfectly. The hardest part of the thing was finding where the line was broken. Once I found that, it only took a few minutes to repair.

00Tahoe · April 8, 2006

When the engine is off for a while, it will go back to cold.

Any ideas? My guess is that some valve expands too much and gets stuck on, and the only way is stop the car (or the airflow) so it'll cool down and pop back into place?

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I had the same exact problem. On the passenger side somewhere near the vent for the floor is the motor assembly to open and shut the airflow door to allow cool/hot air in. When you have it set to hot, it heats up the motor assembly causing the internals to "swell" and bind and then not allowing the door to move back to the cold position. When you turn the car off, the heat is no longer hitting this assembly thus allowing it (the internals) to cool down and no longer binding and going back to cool.

Take this assembly out and open her up. Be careful so as to not let the cogs inside fall out on you. Take the cogs out that have a shaft going through them and lightly sand down the outside diameter of each end of the shafts. Lubricate the ends of the shaft and the holes in the plastic assembly and make sure she rotates nice and smooth. Put her back together and voila!, she's good to go.

A friend of mine and I performed this surgery and have not had any problems since.

Good Luck.

trentw · April 21, 2006

For all that are following this thread:

I've looked at every possible thing to do with this on my vehicle and I'm satisfied that the actuator located near the passenger footwell has failed. The part is only about $30USD so I've ordered one rather than screw around with it.

I'll post my success/failure once I replace the actuator.

FYI - the part number is 52474810 on my 2001 Chev Tahoe 5.3 4WD.

Cheers,

Trent

trentw · April 25, 2006

Failure it is. I installed the new actuator and could not get it to respond at all. I then put the old one back in with the same result. At least the old one used to work cold to hot....now nothing.

I'm completely stumped.

glwguitar · October 22, 2006

Failure it is. I installed the new actuator and could not get it to respond at all. I then put the old one back in with the same result. At least the old one used to work cold to hot....now nothing.

I'm completely stumped.

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So what happend, did you figure it out? I am now having the same problem on my 99' silverado. It just, one day( never had any problems with it at all), started the truck and heat was all I could get, no matter if I had it in the cold or hot position.

Did someone figure this out?