no hot coolant to heater valve??????

[Restoring]

Just to report on my issue...

I did in fact find the source of the problem. I know these systems rely heavily on keeping air out of the system, so I was perplexed when no matter how many times and methods we attempted to clear out any air bubbles, there was still no heat.

The culprit revealed itself inside the Coolant Expansion Tank. It appears this car has overheated once before, as the insides of the tank were severely damaged, and pieces routing coolant to the heater core had broken off and plugged the system up. I was experiencing the same situation as if an automatic transmission version with the secondary built in thermostat (in the radiator) was stuck open. The coolant ran in a perfect loop to cool the motor, but was failing to route any of the hot coolant to the heater core.

anyways, I have heat now!

[danewilson77]

Thanks for update.

Sent from my Thunderbolt using BF.com

[itscoo2pyopants]

I’m having a similar issue on my 2004 325ci with 157k miles. This is my second time overhauling the cooling system in my ownership (pump, thermostats, hoses, expansion tank, radiator, etc). This last go around I don’t have any heat while stationary and poor heat while on the freeway. Not overheating. Temp right in the middle. Bled (and rebled) the system. Getting a code for “auc heating” in the ihka module. Hoses are hot going to the heater valve (from engine) and hot going into the heater core (from heater valve). Hose is cool going from the heater core to the expansion tank.

Anyone else experience this issue? Is there a blockage in the heater core? Heater valve seems to be working. Could the auc sensor be causing this problem? Heat worked before I overhauled the cooling system..