Weird AC/Heat Problem

[joegr]

This is the one correct way to fill and bleed the cooling system. Follow it to the letter.
http://www.lincolnvscadillac.com/tech/Lincoln-LS/CoolingSystemDraining/

 

[max93]

Bumping an old thread. I still don't have heat. The tstat, water pump, and degas bottle, along with hoses were replaced (had an overheating issue). I just had the whole cooling system flushed because I was told that the heater core was clogged. It now blows warm/cool air, but cannot get warm or hot. The fan is working correctly per a tech at the dealership.

Any ideas what else to try? The heater control valve? Replace the heater core?

 

[joegr]

Unplug the connector to the DCCV. If you then get good heat, there is some issue with a temperature sensor or the DATC. If not, then it's either the DCCV, a blockage, or trapped air.

 

[max93]

Unplug the connector to the DCCV. If you then get good heat, there is some issue with a temperature sensor or the DATC. If not, then it's either the DCCV, a blockage, or trapped air.

Thank you!! As for the blockage or trapped air, wouldn't the flush and the shop bleeding it have fixed that? I will try the DCCV!

 

[joegr]

Thank you!! As for the blockage or trapped air, wouldn't the flush and the shop bleeding it have fixed that? ...

Flushes of the whole system are unlikely to remove blockages. If they individually (unlikely, and expensive if they did) flushed each hose, valve, heater core, engine passage, and so on, then that should have found or resolved any blockages.

Bleeding if done correctly (did they follow the factory procedure, or just wing it) should remove all trapped air. However, if there are any tiny leaks or cracks anywhere, the air can come back very quickly.

You can open the heater bleed (engine running and warm) and see if any air comes out. You will lose some coolant and you will be burned if not careful.