I've been to the dealership for the thrid time today and they can't replicate the problem. I get the thing home and sure enough it starts doing it. With the A/C on and the thermostat set to the coldest setting it will blow hot air. I move the thermostat to heat and then back to cold and it works right and blows cold. It'll blow cold for a while and then you can hear the air coming through the vent change and it sounds exactly like it does when you turn the thermostat to heat. The compressor does not cycle on and off and they have checked the A/C system over twice and there is nothing wrong.

This has got to be a problem with the thermostat switch in the HVAC control console doesn't it?

 

Sure does sound like it. I have not bought an HHR yet but its my assumption that the air control doors within the vent system that control whether the air blows across the heater core or not are being triggered just as they would be if you turned the thermostat to heat. Though some cars use a manual linkage tied to the thermostat control to move those doors I suspect in the HHR the air doors are motorized and are either vacuum or electrically operated and are being tripped for some reason. Sounds like a situation that unless its having the problem at the time the dealer looks at it, they will not be able to diagnose it easily but if this is happening alot I'd fight them to replace the thermostat switch and any related items because they are likely the cause.