2005 PreRunner - No Heat

Need some help, please. I have no cabin heat at all in my '05. The blower works great on all settings, but only blows air from the front vents; no air at all from the upper or lower vents (defrost/feet). Temperature gauge gets up to normal operating temp. I checked the heater core hoses at the firewall and both seem to be hot. The upper radiator hose gets hot, but lower stays cold, even after a long drive. Dial for the Temp and vent selector seem to have no effect - air blows out the front only. I bought a thermostat, but I haven't replaced it yet. Anyone had the same problem or have any suggestions on what to check? Its getting cold in PA and I'm using a towel for my defroster. Thanks!

 

It'll be the 87106J damper control servo, or the switch, or the wire between them.
Or it might just be jammed.

 

What you are looking for is the Mode Control Servo.

 

Isn't that what I said?

 

The servo is controlled by the A/C Amplifier.

 

Yes it is, I only included a picture and quoted the name that was in the image.

Not trying to step on any toes.

 

Thanks Jimmy and TGear. I'm going to check it out this weekend. From Jimmy's post - if the Servo is controlled by the A/C AMP, could a problem with my A/C compressor be something to look at also. My A/C compressor went out at least a year ago or so ago and I haven't replaced it due to $$., but the heat just went out about two weeks ago. In fact I haven't had heat since the dealer replaced my frame under recall, not sure if they missed something hooking things back up.

 

The servo should still shift even with a blown AC Compressor.

 

I noticed another issue today that I should have added in the original post - the A/C and Recirculate buttons do not light when they are pushed in. Is there a fuse that is associated with the climate control panel heat/defrost functions. Both lights could be have gone bad, but it seems like everything is associated with the climate control panel. Thanks again.

 

Look for the 10 Ampere A/C Fuse and the 10 Ampere IG1 fuse that is what provides power to the AC Amplifier.

Also check the heater relay under the hood fuse panel.

 

Pulled the glove box and see a servomotor to the left. What should it do if its working right. I don't hear or see it doing anything when change the knobs full hot to cold and go through all the modes. I am going to check the relays today since I am using a towel for my defroster. Will the temp control panel come out; there's not much of gap to get a screwdriver in the gap. I drove about 50 miles yesterday and the lower radiator hose never warms up, is that normal?? .