Troubleshooting auto air

[Florida]

I have a 2002 Chevy Astro van. The air conditioning is blowing cool air but only on some settings.
Here are the symptoms.
When the dial is set to (Max. AC) with the fan on high, nothing at all comes out of the vent, absolutely nothing!
When the dial is set to (AC) with the fan on high; cool air barely trickles out of the vent.
The vent fan is extremely weak when set to high and doesn?t even blow when set to any lower speed.

The vents in the back of the vehicle run strong and cool, it?s only the front vents that don?t work.
Any ideas on where to start?
Thanks for the help. Its already in the 90?s here In Florida

 

[Cofe]

Re: Troubleshooting auto air

Your AC has a high speed fan fuse. Consult your owners manual for it's location.

 

[Bob_VT]

Re: Troubleshooting auto air

You need to do some troubleshooting.

There are links on the net that refer to your vacuum line that may be rotted and wiring troubleshooting. You are going to need an ohm meter

http://autorepair.about.com/library/faqs/bl534f.htm

http://www.justanswer.com/chevy/4mmyd-chevrolet-astro-van-fan-speed-control-portion-heater-ac.html

 

[puddle jumper]

Re: Troubleshooting auto air

Like Cofe said check the fuse. It does not sound like a AC problem but a blower motor problem. You may have a switch or rheostat problem.

 

[Bob_VT]

Re: Troubleshooting auto air

Blower motor resistor and relay pack??

 

[polk county]

Re: Troubleshooting auto air

I got it! Thanks for the help everyone.

It was the underhood A/C relay. I switched the A/C relay with another identical one and the A/C worked.
thank again!