Another 99 (5.7) with no heat question

[Bentonmike]

Hi guys, I've searched the forum for this problem and came across one thread for it. I tried the two recommended things, changed the thermostat and flushed the heater core with CLR. No luck. Antifreeze is topped of, so that leaves the blend door or the climate control panel. Can either one cause the "no heat issue",and if so, any ideas on how to test them? Thanks in advance Mike

 

[lesterl]

Ok, so you have NO heat what so ever?

First, are both heater hoses getting hot - NO? Heater core plugged. YES......

Second, run the truck with the AC on, turn the temperature to Heat (leave AC running), does the temperature get warmer (not hot, but not cold?) - NO? Bad Blend door Motor. Yes.....

Third, how hot is your engine running?

 

[Bentonmike]

Thanks for the reply. Yes both hoses are getting hot, Tahoe is running like a champ I'll check the A/C test tomorrow. Thanks again.

 

[lesterl]

NP, hope some of that helps.

 

[Bentonmike]

Ok, air doesn't get any warmer, if it did very little????

 

[lesterl]

So now we need to see if your blend motor is actually turning (motor could be internally bad- been there done that). There is a vent selector motor by the drivers feet, not the one we want, another behind the glovebox is the blend door IIRC.
http://www.justanswer.com/chevy/2g9zn-blend-door-1999-tahoe.html

 

[Bentonmike]

The blend motor is turning, but it doesn't make any noise or vibration (by feel) when you switch it to heat. I'm going to see if I pull the radio out if I can get to it. Thanks again for the reply!

 

[lesterl]

Really probably ought to visually look at the motor shaft to see that it is indeed turning.

If the motor is turning, perhaps the blend door is broken....

 

[Bentonmike]

I'm taking it to a shop this week, I'm out of time where I can work on it. I'll let you know how it goes, but my guess is that something in there is broken. Thanks again

 

[lesterl]

Cool, keep us posted, Fingers crossed it is something cheap.....

 

[sawmkw]

Ok, so you have NO heat what so ever?
... Third, how hot is your engine running?

Why is this question important? I checked my thermostat a while back and it is opening and closing but my engine temperature never gets much above the hash mark between 100 and 210 degrees so maybe 160? Neither do I have vacuum at the heater control valve.

 

[Bentonmike]

Well, after a month, our heat is fixed! Turned out that someone before I bought it had put a new water pump on the Tahoe and somehow routed the hoses wrong. The water pump was the last thing that my mechanic suggested, and he saw the problem before he changed it. Thank you for all of the help and support!!!!