I have a 2005 Chevy Trailblazer. V6. the a/c & heater does not blow air. we checked all of the fuses to the a/c, heater, and the blower motor, and all are good! When a/c turned on it does not blow air but the unit under the hood gets really cold and even frosted over last night so apparently the a/c is working just not blowing! Any suggestions??[]

 

your resitor pack has failed.
under the globe box...

 

if you have manual AC..

Assuming Fuse# 35 in the Under Hood Panel, Fuse# 44 in the Rear Panel are both good, and Speeds 1-4 work, you either have a bad Blower Motor Relay, (located in the Blower Motor Resistor Module) or a bad Fan Speed Switch in the HVAC Control Panel. Turn the Ignition Switch to RUN and set the Speed Switch to 5. Behind the glove box, at the Resistor Module, see if you have 12VDC at the ORANGE wire. If you DO[/b][/u], the Resistor Module is bad. If you DON'T[/b][/u], see if you have 12VDC at the RED wire. If you DO[/b][/u], the Fan Speed Switch is bad, if you DON'T[/b][/u], re-check Fuse# 35 under the hood. If the fuse is good, then the power feed for the 5 Speed has been cut somewhere between the Resistor Module and the Under Hood Fuse Block. This wire is RED all the from the Resistor Module to the Under Hood Fuse Panel.Good luck... [/align]

 

the above was from a thread on www.trailvoy.com web site for Envoys/Trailblazers/SAABs/Isuzus/ basically the TB chassis.

 

Well before the a/c quit. it only blew on speeds 1-4. 5 didnt work when you ran the a/c.and it worked on speeds 1-5 when heater on. Now it does not blow air on any speed for a/c or heater.