1995 Chevy 1500 Heater wont work

[yz125motomxer]

blow cold air when its cold outside, and blows warm air when it warm out. I can control the amount of air that comes out, but i dont have any defrost at all, and no warm air. Dont know whether to replace the heater core, thermostat, or the air control box in the dash? thatnks for all who helps, its cold here already and im freezing on my way to work.. lol lol

[MPMARTIN]

yz125motomxer wrote:

blow cold air when its cold outside, and blows warm air when it warm out. I can control the amount of air that comes out, but i dont have any defrost at all, and no warm air. Dont know whether to replace the heater core, thermostat, or the air control box in the dash? thatnks for all who helps, its cold here already and im freezing on my way to work.. lol lol

Although I'm not that familiar with Chevys, I see one of two possibilities. Most heater controls are either vacuum or cable operated. In your case it could be that the water control to the heater core is stuck in the off position. Or, the damper in the heater plenum isn't operating and directing air through the heater core. Either way, it's a difficult thing to repair, looks like it's dealer service time.

[Gromit]

worse comes to worse, track the control to the plenum and manualy flip that sucker. there should be an actuator arm there. come spring, flip it back.