I have recently acquired a acura legend coupe. Now that the weather is getting colder, heat is required.
The temp gauge starts fluctuating, once i get the wheels moving it goes back down. and sitting idle or when i stop moving - no heat comes thru the vents, and the gauge jumps back up. I thought it was the thermostat, had it changed and now its worse. I don't get any heat inside unless the a/c is on and wheels are moving, and the gauge doesn't come down.

A mechanic said that the system might have to be bled to let any air out.

should i change the thermostat again? could it be anything else?