No Heat in Cab...

I have no heat in the cab

...I have changed the thermostat :banghead:
...I have checked the waterlines in/out heater core (both lines @ temp.)
...I took apart the dash and "looked at" the switch ass. :eek7:
Could the temp control switch be bad? :sunglasse
I would appreciate any thoughts or possible solutions.

Your friend in INDY! :smokin:

Do any of your other vent systems work? A/C, outside air, defroster etc.


I would suggest checking your vac lines...if on eof them is severely cracked, it may not be able to move the 'doors' in the vent system to allow hot air to come through...

(I started another thread, so not to hijack yours)

I also have poor air temp, although the airflow is decent, which makes me think it's the coolant flow, not so much the heater unit. MIne is a
89 S10 Blaz/ 4.3 TBI engine (no modifications)/Rebuilt 2yrs (20k mi) ago by Jasper Co. New radiator replaced with engine. (no blockages) Antifreeze is full & mix good to –10 degrees. Not sure of the T-stat rating, but Im sure it’s not the 160 “performance” one.

I suspected the inner air door maybe wasn’t opening/closing all way because the A/C wasn’t super cold either. But the airflow out the bottom is decent strength, just not very warm. My vacuum switch does hiss a bit, but it does function by moving the airflow from Floor-vent-defrost-etc? The hot/cold lever seems to “stop”, which makes me think it is opening/closing all the way?

How did you visibly inspect the movement? Did you have to tear the whole dash apart? If you find out what the problem is please e-mail me & I’ll do likewise. [email protected]

Try backflushing the heater core with a garden hose.