94 k1500 poor heater performance

devon_4 · January 17, 2020

Having issues heating the cab of my 1994 k1500. Engine gets too operating temp and heat blows luke warm, not hot like it should. The only way to get any heat out of the system is to put it on recirculate which causes the windows to fog so then I have to switch back to defrost and i lose all the heat again. Coolant is flowing through the heater core as I can see it coming back into the rad, inlet hose is quite warm to touch but not unbearably hot, can comfortably hold my hand on it. Outlet hose is cooler but still has heat to it. Was it just a poor design? Not sure what the next step is.

CamGTP · January 17, 2020

The one hose coming into the heater core should be so hot you can't touch, the other should be slightly cooler.

Sounds like you should back flush the heater core to see if you can get better coolant flow into there.

Jv50347 · January 26, 2020

Definitely agree with cam on the heater core. Might be worth replacing it. If the cooling system has been opened recently it could have air in it. My s10 had the same issue after I flushed the heater core it will run you out on 30 degree day. Also could have thermostat acting up.