1994 - No Heat this morning

[Mstg007]

Anyone, have an idea why the climate control would be blowing cold ac air out of it when it is set to 75 degrees? It was a fun chilling experience this morning drive into work.

 

This is a total first.

 

Thanks guys!

[94 olds vert]

Heater core issues? Thermostat not opening?

[Imp558]

....... and a bunch of vent and blend door solenoids, vacuum actuators, grounds, and then there's the control head itself. might be a good idea to look over all the vacuum lines under the dash and under the hood for starters

[Mstg007]

I keep getting referred to a heat blend or actuator. I have the service manual but I can not see where it is in relation to under the dash. Any one have a photo of what it looks like and where? lol.

[Schurkey]

Anyone, have an idea why the climate control would be blowing cold ac air out of it when it is set to 75 degrees? It was a fun chilling experience this morning drive into work.

1.  How do you know that the AC is engaged?  Did you SEE the compressor running?

2.  What is the ambient temp?  If it's 95 out, and the thing is set to 75...sure, the AC will be engaged.

3.  Coolant level correct?  Air in the cooling system can accumulate in the heater core = no heat, ambient air blowing through the ducts even if the AC is not engaged.

4.  Thermostat stuck OPEN will allow cold water through the heater core = no heat, ambient air blowing through the ducts even if the AC is not engaged.  Does the engine warm up properly?

5.  Lack of vacuum to the HVAC system should result in the air coming out the defroster.  If the air isn't coming out the defroster when the control is set to vent or floor, the vacuum system is likely OK.

6.  Check the air doors and grounds and actuators and other weird stuff AFTER you verify the engine is warming up and full of coolant.