No heat

[Chevylover54]

I went out to start my 01 GAGT today to warm it up. When I came out later I had no heat blowing out of the vents.

The blower motor is working. I replaced that already. I do have a slight antifreeze leak. Looks like the LIM again. However my antifreeze is full. It has been blowing warm air even with the leak and has always blown warm air when I had leaks before.

The temp warms up just fine in the car. I left it running for about 15 mins and when I went outside the temp was normal. The last time I drove it was about a week and a half ago and it was fine then. It just all of a sudden decided not to blow warm air.

I'm a little confused since it stopped blowing warm air all at one time. Could it be the heater core being plugged? Could I feel the return line from the heater core and see if it is warm after the car warms up? If so which hose would it be. There is no water on the passenger floor board. If I do need to change the heater core is it a hard job? I have changed my head gaskets so I do know how to work on cars but I have never done a heater core.

I didn't drive it to see if the air started blowing warm while driving down the road. I had to get to work so I took my 02 Monte Carlo SS to work.

Any ideas?

[gagt Mechanic]

there are two hoses going to your heater core, withe the eng at op temp, both hoses should be hot, like your radiator hoses, if one is hot and one is cold, you have a problem in your heater core, if they are both hot, you have a problem in your dash, blend door, if they are both cold, you have a problem in your eng.

[Chevylover54]

gagt Mechanic, thanks that makes perfect sense. I'll let it warm up tonight and check the hoses.