On my 1991 chevy silverado 1500 I cannot get heat in the passager compartment -- the heat door will not open. The indicator (on the control head) immediately goes to arrors all the way across after the truck is started. The blower only blows our cold air. I've changed the actuator switch/motor under the dash and the head, checked and filled coolant level but still the same (no heat) problem. Please help. Thanks, Eddy in Alabama

I know this sounds nuts but I just did this to my Granddaughters truck and it works. Turn the key off open the door for 90 seconds close the door turn the key on but do not start the truck, press the gas pedal to the floor three times and shut the key off and wait 10 or 15 seconds and start the truck. This will reset the idle air control and should let the truck idle ok.

There is a vacuum controlled actuator under the dash that opens a door exposing the heater core to the vent system. Sounds like the door isn't opening. Check your vacuum lines under the dash..

possible climate control problem or the acctuator that opens the door for air flow from heater core. Check for a vaccum leak in the engine compartment or a bad diaphram on the acctuator, and even a bad cable from the control lever/knob.

need new A/C controler in dash

sounds like you need to check some fuses does your radio and air control lights come on @ all or your interior lights when you open the doors you have two places that fuses are located one under the dash and the other in the engine compartment your user manual should show you where to locate them and you might see a diagram to see what fuses are for what components on the car my truck has a pannel on the driver side of the dash it is a triangle shape pannel that pops out so it can be tricky to locate the fuses some times

Might work!!!! get under the front end and try to pull the bonnet release cable when open take the live off the battery and keep arking it off the battery may open the doors if central locking.

The temp blend door, or blend door actuator may be faulty. You can check this by watching the movement of the blend door actuator while you turn the temp selector knob. If the actuator is working, then it may be the blend door, or blend door lever broken. If these are ok then the control head may be faulty.

Had the same thing happen to my truck, the blen door actuator is under the console on passenger side, but the heater core is going to be clogged if you dont have any heat coming through, but a/c works..

The fuse is either in the fuse compartment on the side of the dash when the drivers door is open, or under the hood on driver side in a black box. Look on fuse cover it should show what each fuse is for.

Well it would be the "mode door GM pt#88986538" or the "mode control cam actuator GM pt#89023358" on the side of the heater case. The door would control where the air comes out and the actuator tells the door where the setting is at on the control head.