ello all, First time poster here.

I have a 2003 Suburban, 5.3 engine that has a problem with not having heat. It is at my mechanic's now. He has ruled out all the usual suspects such as bad thermostat, low coolant, bad heater core.

It puts out heat for a while, then suddenly starts blowing cool air. Later, after a while, it starts with heat again.

He thinks it may be the interior temperature sensor but is not yet sure. He said he has never seen a problem like this and he has been working on vehicles 40+ years.

Does anyone have any idea as to what it would entail to replace the interior temperature sensor and what it may cost?

Thanks.