My heat does not always kick in. The electronic unit will turn on but it will blow cold air, then start to work, then stop blowing hot air and start to blow cool air.

Whats going on here? This is with the motor at normal operating temp.

 

Why 2 threads on the same topic? Bleed cooling system, if that doesn't fix your heater and temp gauge issues, then replace the Autoblown thermostat with an OEM unit.