check the temp guage if low change the thermostat
The blend door actuator may not be working.
Check Antifreeze level..make sure there are no leaks under the vehicle.
My 2001 Chevy Blazer was blowing cold air when I had the heat on. My husband flushed the line to the heater core and a bunch of junk came out and now my heat works great. My 2001 Chevy Blazer was blowing cold air when I had the heat on. My husband flushed the line to the heater core and a bunch of junk came out and now my heat works great.
The heater valve could be failing to open for one reason or another.
Low coolant in the system. Defective heater control valve. Clogged heater core.
Either a faulty thermostat or you have a low coolant level.
If it still blows cold when it is at running temp, check the engine thermostat, its probably stuck in the open position.
good question
Either the a/c system is low on freon or the evaporator has an internal restriction....
Coming out of the vents around 43 degrees
Sounds like a malfuntion in the heat blend door actuator call your local autozone for more info
most likely it's a bad thermostat, or your vents not working properly.