Low coolant, failed thermostat, partially plugged heater core...............
To the right
It is because your heater is having to heat up so its blowing cold air out while its heating up.This means your heater is not very efficient and it needs to be checked.
Only blows cold air with the a/c on while driving, your cooling fan or fan clutch is bad depending on the year, make and model.......... Only blows cold air with the heater on while driving, you will have a bad or broken internal a/c - heater control door.....
Check the following items............... 1. A/C heater controller. 2. A/C heater controller doors.
check the wireing harnesses
it could be the heater core and ac housing unit that allows hot air to be mixed with the cold air or it could just cancel out the cold due to the motion of the car
You will need to replace the rear expansion block valve and the recharge the system with freon and oil..............
A fan heater blows air over a heating element to warm the room quickly, while a radiant heater emits infrared radiation to heat objects directly. Fan heaters are more effective for heating a room quickly, while radiant heaters provide more targeted warmth.
The connector is of the Quick disconnect type. simpley Squeeze the the inner lock tabs with a pair of common pliers and twist while pulling.
Turn real sharp while moving and see if you feel the front wheels jerking
The 2003 Chevrolet Trailblazers has two heater cores. One operates the front area of the vehicle while the other heats the rear of the vehicle.