1999 Tahoe, Temp Valve Actuator?

[derekjl]

The heat on my Tahoe only blows luke-warm, not HOT like it should. The A/C works fine. I have already flushed the heater core and replaced the thermostat, same result. I was advised that the next step would be to replace this actuator under the dash. The blend door works fine. I cannot tell which part to replace according to the diagram below. Which actuator actually changes the temperature setting, #11 or #38? Thanks.

http://www.gmpartseast.com/Page_Product/PartList.aspx?MakeUrl=Chevy&CatalogUrl=&ComponentCode=TX0905301&SectionCode=09&EngineCode=L31&TransmissionCode=M30&ModelCode=K10706&Vin=1GNEK13RXXJ517642&ProductionDate=0-0-0&VehicleInfo=K1500%20or%20K2500%20or%20K3500%20or%20Suburban;1999&CatalogCode=54C&Year=1999

EDIT: Looks like the full part number for #11 is 89018681 and this is what it looks like:



The full part number for 38 is 16167292 and here is that pic:



I mean seriously, WHAT is the difference?!

 

[SunlitComet]

11 is servo controlled. 38 is like a spring return type. no power and signal and it springs the air inlet open. with power and signal it closes it for recirc. No in between positioning like 11.

---------- Post added at 03:45 PM ---------- Previous post was at 03:45 PM ----------

That is the difference.

 

[derekjl]

11 is servo controlled. 38 is like a spring return type. no power and signal and it springs the air inlet open. with power and signal it closes it for recirc. No in between positioning like 11.

---------- Post added at 03:45 PM ---------- Previous post was at 03:45 PM ----------

That is the difference.

So I should start by replacing #11?

 

[SunlitComet]

It sounds like it. The recirc motor would not do that. But you did say the blend door is fine. So you know for sure its motor is defective? How about the heater core water valve or its control circuit? I would turn the key on and the fan on lowest setting to keep quiet and turn the temp knob in steps to see if you here it moving about each time from one end to another.

 

[derekjl]

Your theory of the truck running too cold is a good one. I started it tonight and got up on the highway and the thermostat literally opened at what looked like 170 degrees. After that it settled at 150 degrees or so like I said. I'm going to start with a new Stant SuperStat and see what happens after that. Changing it can't take more than 15 minutes right?


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[derekjl]

Not sure if anyone can pick up on this, but there is a little "click" sound coming from under the dash by the 12v outlet every time I move the temperature dial just past the blue line into the red and back again. Does this indicate that the actuator could be getting stuck? Sucks having lukewarm air when the dial is all the way to the right.

https://vimeo.com/110107899


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