[gXpG608]

if there is something wrong with coolant temp the pcm goes into fail safe mode and runs the fan to minimize engine damage. scan for codes. if your temp is low the thermostat is probably stuck open.

 

[gXpG608]

ya the coolant wouldnt get hot enough for your heater to blow warm air. onstar does give you a code but you gotta have onstar account. you would probably get a low temp reading code, i forget what it is. if there's no codes you might wanna check the outputs from the sensors, see what they read.

 

[gXpG608]

no idea, i always use gm's service manual. if you can get me a code i can check it when i get back to work.