Heater/defrost problem w/ 00 Bravada

When I turn my heater/defrost on, sometimes it works and sometimes it doesnt work very well. Tonight I started my car to let it warm up. 15 minutes later I went out and my windshield was still icy. I hopped in and found that there was no air coming out of my defrost vents. When I turn the fan speed up and down, I can hear it get quiter and louder, but no air comes out of the vents. Even on heater only. Living in Minnesota, I need my defrost. It never really gets hot. Just tolerable. 1 friend says vaccuum leak and another says blower motor. Any ideas or suggestions? Hurry....it's snowy and cold up here and I need heat and a non-icy windshield. Thanks!

Manual or automatic climate control?

not sure. i have to manually turn it on, but there are auto settings for both the fan speed and the heat/defrost knob. so i guess its manual since i have to turn it to auto. it worked fine today for about 30 minutes. after i drove for a bit, the air flow got slower and slower. Manual or automatic climate control?

I don't know so this is just a guess, maybe the blower motor is going bad on you.
Do you have an Owners Manual to check for variable fan speed information?

I don't know so this is just a guess, maybe the blower motor is going bad on you.
Do you have an Owners Manual to check for variable fan speed information?

Im gonna buy a new blower motor and try that. It isnt very expensive. I replaced the one on my 96 Taurus once and it was easy. Where, and how, would I go about it on the 2000 Bravada?

before i replace the motor, i wanna make sure you know that the fan works, i think. it gets louder when i turn it to high, and quiter when I turn it to low. just no heat comes out the vents or the defrost vents. i was having trouble with the a/c in the summer too. same problem, only i was lookin for cold air then. still sound like a blower motor?

You have Automatic Climate Control and it requires a scan tool to diagnose it. Probably not the blower motor if you hear it change speeds.

You have Automatic Climate Control and it requires a scan tool to diagnose it. Probably not the blower motor if you hear it change speeds.
Where, and how much, can I get a scanner? How do you use 'em?

Scan tools are hand held and entry level body capable ones start around $400. Top of the line is the Tech2 scan tool, it sells for around $4,000. Perfect example of "you get what you pay for". The Tech2 is the GM "dealer issue" piece and is bi-directional. Before you buy any scan tool, make sure it is body capable. They're available online and at most auto parts stores.

You have Automatic Climate Control and it requires a scan tool to diagnose it. Probably not the blower motor if you hear it change speeds.

It always sounds like it blows the same...sound wise. After it runs for 15-20 minutes, the airflow is gone. It sounds like the fan's running, but no air is coming out. Help at all w a diagnosis?????

It always sounds like it blows the same...sound wise. After it runs for 15-20 minutes, the airflow is gone. It sounds like the fan's running, but no air is coming out. Help at all w a diagnosis?????

First thing.
Make sure you have good engine vacuum to heater controls.
Check engine vacuum lines from engoine to vacuum tank and from vacuum tank to heater controls.
A lot of vacuum tanks are in underside right front fender.
Plastic lines will crack or come unpluged.
MT