please help no heat

[modularnotch]

hey any of u guys please help my buddy has a 98 cadillac catera it doesnt put out good heat and sometimes no heat at all what could this be a heater core/coil or a thermostat we checked coolant its all filled up well thanks any help would be appreciated

[elwesso]

It could be a heater core, or maybe a mix door... Hopefully Jeff will come by and be able to help.

[Vesicant]

You can try and reset the mix doors .. what wes was talking about:

With the key in the on position (not running). Hold the auto and off buttons on the climate control for 5+ seconds.

There should be slight mechanical sound of the doors going back to their original location. Another posibillity is that one of the doors isnt working, or your heater core is blocked (as wes said), and possibly the heater valve. Usually the broken ones leak but Im sure they can stop working as well. It can be any number of these issues that will not allow heat.

Heater control valve information: http://www.cadillacforums.com/forums...19&postcount=3 (heater control valve)
http://www.cadillacforums.com/forums...20&postcount=5 (heater control valve)

[Timelode]

This might a really lame question, but is your friend using the automatic climate controls? I noticed that if we don't set the intial temp at 75 or better on both sides, the systems throws out luke warm or even cold air. Once it's starts to get warm in the car we down to 70 or to where we really want it for each side and it maintains a good comfort level after that.