Ok... So not long ago I noticed that my heat has been dying and I am not sure when it started, but I know that the defroster works perfectly fine, but my Blazer used to heat up in 5 minutes, but now I will drive for 45 min. and it won't feel any different. I have taken the dash off a while back, so that might do with something and I checked the radiator fluid and it was fine. I really don't know what it could be, but it it horrible driving to school in 5 degrees in the morning and not being able to feel your hands or feet for 2 hours, so please help me with this... I have a 2000 4x4 LT

 

bad thermostat, clogged heater core have you checked either of those? i would replace the thermostat and flush the heater core

 

Ok. It still blows air just freezing cold air and it does warm up eventually but not a lot.

 

yeah sounds like a stuck open thermostat

 

Take a look at the coolant temperature gauge...bet it is showing a low temp. A quick fix would be to wedge a piece of cardboard over a portion of the radiator to block some airflow. Do not block off the entire radiator or you will overheat the engine and be walking to school...in the snow....uphill both ways.....

Changing the thermostat takes about 30 minutes; cost is about $10.

 

Ok... But would it be the thermostat even if the defroster still works?

 

possible blend door issue then. when you said truck doesn't heat up are you talking temp inside or coolant temp i thought you meant coolant temp.

 

No, temp inside. The coolant temp is just fine.

 

Something does not make sense here.....you say the defroster is working fine...so I assume nice warm/hot air blows onto the windshield...is this correct?

But there is no warm/hot air blowing out of the floor vents....is this correct?

If so, then sounds like the blend door is working fine but the vacuum actuator for directing air flow is not working. You say you had the dash out recently...perhaps you did not reconnect the vacuum line to the actuator or something is preventing it from working.

Have to let me know if I have the correct understanding or not.

 

Yeah that sounds right