I have a 2005 Corolla S w/ 1.8L and the heater does not blow hot air when the engine is fully warmed up. It will blow hot air for a few seconds if you turn the system off for a few minutes but then the temp of the air drops to something I would describe as luke warm. I am having the same problem in my Jeep and the fix is to flush the coolant system to clear the heater core. Could this same process be used to correct the issue on my 2005 Corolla S or are there other things that could be causing this?

The engine does heat up and get to normal operating temp and does not over heat. The coolant levels are good, the temp can be moved from hot to cold and the temp of the air does change, can go to the defrost and any other setting also the recirculate works. Any other help with this problem would be appreciated as I don't want to take it into the stealer ship

Thanks.