So my heater chose the absolute worst time to give out on me. Heres the problem I'll have the heater set to on, full blast, and usually when I start up the car it works. Then it will cut out on me. It will randomly cut in for a few seconds and then it will cut right back out. Anyone have a clue whats going on? Is it just a simple wiring problem? Is the heater core going? Maybe the motor? I'm looking for the most likely subject before I tear into the heater system.

 

It sounds like the heater motor is about to go. To test it, the two wires going to the motor are on the engine side firewall. Unhook those two wires and, using some extra wire, run one of them to the positive side of the battery and the other to ground. If the motor acts the same way as before, then you can rule out any switches, etc and just replace the motor. If it stays on and runs constantly, then you probably have a switch that has grunge built up on it.

 

Could also be the resistor for the motor with a small break.

 

+1 on the resitor its located on the header box where 2 wires plug in