A/C dosen't work

[gm4x4]

it has been snowing for two days. the first day i was driving my truck with no problem the heater worked fine. today i started my truck for 15 min when i tried to turn the heat on it wouldn't work. i tried again and again without any luck so i turned the truck off and went out for 5 hours when i came back i tried the heat again it works fine.

 

 

anyone could tell me why the heater won't work ...??

did this happen to any of u guys !!!!

[carguru]

Could be a number of things. Problems with the thermostat, something stopping the flow of coolant to the heater core, blend door or actuator stuck in the cold position. Where was the temp knob when this first happened?