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Blazer heater control doesnt put it where it should go

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New User

Oct 13, 2012, 11:17 AM

Post #1 of 2 (1465 views)
Blazer heater control doesnt put it where it should go Sign In

I have a 2004 chevy s10 blazer 4wd with 4.3 and roughly 160k on her . I just bought it 6mos ago and I noticed that i always get air coming through the vents even when the heater control is in the off position. Also now thats is cold I 've notice the heat is not really hot and does not come out well of the defrost ports, only the vent port. I already had the thermostat changed when i got it cause the there was no heat registering from the engine . How do I get more heat and coming out where it should

(This post was edited by tjpcasey on Oct 13, 2012, 11:20 AM)

Hammer Time
Ultimate Carjunky / Moderator
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Oct 13, 2012, 12:00 PM

Post #2 of 2 (1445 views)
Re: Blazer heater control doesnt put it where it should go Sign In

The mode control and the temp control are 2 different circuits and actuators. the only thing they have in common is the control head itself.

As far as temp..........

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If not too hot to hold, then you have to look at the actual engine temp and if that is up, if it is, then your looking at a restricted heater core.
If you find that they are both too hot to hold, then the heat in that vehicle is controlled by a blend door that regulates heated air flow. it is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
If they are both not too hot to hold on to, then you either have a restricted heater core or the system is not completely full and getting air pockets for some reason.

The mode doors are also controlled by an electric actuator on the left side of the housing. There's always the possibility that someone previously had the HVAC housing apart and messed up all the doors.


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