02 Heater temperature issue

[cj99]

Recently I drained the antifreeze thru the drain plug on the radiator and refilled it thru the coolant reservoir tank. Ever since, the my heater doesn't seem to be putting out hot air like it did before I changed the antifreeze. I have to turn the temperature knob to 100% heat to get good hot air out of my heater. Before this, I could get enough hot air at about the 50% position.

My engine is still showing to be heating up to the same temperature - about 205 degrees - as before.

Any suggestions?

CJ

[j cAT]

Originally Posted by cj99

Recently I drained the antifreeze thru the drain plug on the radiator and refilled it thru the coolant reservoir tank. Ever since, the my heater doesn't seem to be putting out hot air like it did before I changed the antifreeze. I have to turn the temperature knob to 100% heat to get good hot air out of my heater. Before this, I could get enough hot air at about the 50% position.

My engine is still showing to be heating up to the same temperature - about 205 degrees - as before.

Any suggestions?

CJ

it will help if you give vehicle details, mileage, type, maintenence history, about this issue

[RaeRae1]

Agree with Jcat but did you also check again after running the vehicle to make sure your radiator fluid was full? You probably filled it when cold and once the thermostat opens up the fluid is now at a much lower level. Check fluid levels again to make sure your fluid level is full. *do not open the system/remove radiator cap when it is hot*

[cj99]

Antifreeze is full. Vehicle has 80.000 miles, this is the first time I've changed antifreeze. Its a 4.8 engine.

Read somewhere that the BCM might have to be reset?

[rjeffery]

Check coolent level when engine is at operating temp with the heater on max (recirculating & max blower), bring engine speed up to ~2000 rpm for a min or two, leave expansion cap off. This should circulate coolent through heater core. Check level again and add coolent as needed. If this still doesn't work your heater core may be plugged.

You don't have to reset BCM after flushing coolent.

[2000CAYukon]

Are the hoses to the heater core getting warm? Is one warm and the other cold?

//2000CAYukon

[j cAT]

i dont believe by just using radiator drain plug heater core was drained by any amount. proceedure as mentioned is to add coolant and keep coolant res. cap off until engine gets to 195deg f. this engine does not have purge on thermostat goose neck, but i never had any problems doing it this way.........

[Tdragone]

Originally Posted by rjeffery

bring engine speed up to ~2000 rpm for a min or two, leave expansion cap off. This should circulate coolent through heater core.

You beat me to it. This is the trick that finally 'burped' my cooland system. Some trucks while under pressure won't eliminate air pockets.