2006 Chevy Impala 6 cyl Front Wheel Drive Automatic 77,800 miles
At operating temp, with blower on while moving, heater air is hot and " normal.&Quot; When stopped and idling, the warm air turns cool. When RPM's increase from 700 to 1000 in neutral, stopped, the heat returns to normal.
Thermostat replaced 3 weeks ago and sufficient heat was confirmed with laser thermometer while in the shop. Now, its doing the same thing again. Where should I look next to resolve this issue?
Try bleeding the sys this way first, its hard to get the air out of the cooling sys on these vehicles. With the engine cooled off, remove the coolant pressure cap.
Remove upper heater core hose from the metal pipe on the engine.
Add coolant to the metal pipe, until full.
Raise the rubber portion of the heater core hose as high as it will go with it still attached at the heater core. Using a funnel, add coolant until the hose is full.
Reconnect the heater core hose.
Start engine, have assistant raise the RPMs to about 1500 to 1700 RPMs, top coolant off at engine, then before lowering engine RPMs, install the coolant pressure cap.
Fill coolant reservoir as necessary, then check the heat at idle.
Note: If there is still a lack of heat at idle, perform the cooling system draining and refilling procedure
post back with what you find.
April, 13, 2009 AT 1:34 PM
I confirmed coolant was full by checking level in filler neck and resivoir when cool. In addition to the new thermostat (I believe I did NOT need) I added small amounts over 3 days, then bled the system as suggested by Brian 1.
Now I have heat at idle as expected, it gets uo to tep quickly and the " gurlgling" I heard at start up for several months is gone. I suspect coolant level was somewhat low all along, but " check coolant" light never appeared.
Thanks for the information.