Heater not working 2000 small block Blazer

johnnyboy1950

My heater seems to not be working properly. The temp switch seems to change the temp ok (when engine is hot and sits still for a few minutes, I get some warm air) not sure if function switch is working. It seems to move too freely??? Wondering if there is anyone familiar with this problem or could lead me to look for the cause further!!! Novice but capable mechanic, thanks

Mr_Shiftright

This post is a bit confusing. You say your heater isn't working but then you say you get warm air. So do you get warm but not hot air? Or do you get hot air but only in one function (floor or vent or defrost, etc).

johnnyboy1950

Thanks. The warm air is from engine heating the ducts only, not heater and only initially when standing still. I don't think I'm getting anything from heater. I do get a tiny amount of temp. rise when I turn thermostat to warm setting but not real heat. I think this is constant regardless of the vent, heat, defrost setting. Thanks again for the help!!!

thecardoc3

Is the blower motor running and do all of the different speeds work?
Do the controls for the HVAC assembly re-direct the air to the varying output positions? Defrost, Dash, Bi-level, Floor?

johnnyboy1950

Blower seems ok....vent control seems to move too freely, but I'm getting air out of all locations and doesn't seem to change much from one to the other. I read there is a hot-cold flow switch in one of the lines. I'm going to try back washing the heater core first. Does this switch need to be removed first. Thanks so much!!!