00' blazer with new heather core,new water pump,new thermostat,new fluid,new cap.ok problem is car is warmed up and i have very little warm air,the air flow is good but when i switch to the floor setting right before it switches the air out the top vents gets really hot..if i switch back same thing,really hot air for a few seconds then back to cool/warm air..could the computerized climate control be bad?is there a way to test it.thanks for any info

 

The climate control could be bad, or you could have a bad engine coolant control module/switch(about 10 bucks at autozone), or you could have just really clogged up top vents not sure just suggestions

 

I have a similar situation going on. No heat, but when the temp control **** is rotated, the blower sound changes as if the mixing damper is moving. The heater hose from the intakle to the firewall is hot, but the return is cool. Normal wisdom says the heater core may be plugged, but I am curious what the engine collant temperature control module switch is and how does it affect heater temp? Where is it located?

 

my hoses going to heater core are hot.i also checked the flow of them and they flow just fine.my vents flow alot of air.but il look into the ccm tho.thanks for the info.

 

You may want to make sure there is no air trapped in the heater core. Very common problem after having the cooling system opened up or if you have a minor leak. A plugged core is possible if the duracool antifreeze gelled.

 

Makes me think that the blend door (mixes outside air with heated air) is not operating correctly.

 

This ^

and you may have a vacuum leak causing the blend door to not work properly. I know the dash comes out to do the heater core and there are a lot of things to remember to reattach. You may have missed a vacuum line. Try to test the main vacuum line that goes into the cab. You shouldn't be able to pull much air through it. Check the main line that goes into the cab with the engine running to see if there is vacuum created. You should be able to stick your finger over it and tell. Hope this helps.