Hello i have a 02 z71 with the 5.3 flex. My question is what would make the rear ac blower not work? My problem is that no air blows from the rear ac unit. I’ve started by replacing the control switch (both front and back) and that didn’t fix it. Tried putting 12volts directly to the fan and it turned on. So it’s not the fan(replaced with junk yard one just to be safe) and I’ve tried 3 different resistors for the back. One new and the rest from junk yards. I’m lost. When you change the temperature or the direction you can see it change direction when the plastic panel is removed, so I know it’s got power. Is there a module I don’t know about. It’s not auto ac either btw. Any suggestions would be great!

 

Check the IGN-3 fuse in the left I/P fuse panel.
Check for power (key in RUN) at the resistor unit on the Orange(fuse RR-HVAC) and Brown(fuse IGN-3) wires.
Let us know what you find.

 

Ok checked the IGN-3 fuse and it’s fine. Checked orange wire going to resistor and it’s got 12.3 volts along with one of the brown wires. The other brown wire has no voltage whatsoever.

 

Not sure what other brown wire you're checking, the schematic shows only one brown wire.
I hope the wire that has the power is going to terminal C on the resistor module.
First guess is you've lost the ground connection on the black wire going to terminal A, or the black wire on the controls (terminal A8 control connector).
With the key on, blower control set for HIGH, measure the purple, black, white, red and dark blue wires.
You should have 0 volts on the Black and White wires. 12 volts on either one indicates bad connection to ground.
Good luck,
B

 

Funny thing is that as I was taking the connections off I heard a click. ( key was still in the run position and the fan on high) and so I started wiggling the connection and then I wigged the other connections (on the resistor) and my god the fan turned on. So long story short it was just bad connections on the resistor. Particularly the ones controlling the fan. So I took the connections apart and bent the tabs to be tight. Fan only works on the high speed… no worry because I have 3 of these stupid resistors, so I switched the resistors and boom. Fan now works on all speeds. Thank you for your help!

 

Thank you for the update !!
Glad you found the problem.

 

Over 4 decades ago I had an intermittent stalling/no start issue on a - wait for it - 1974 Chevy Luv truck, seemed like the truck had suddenly run out of gas. Then I noticed that the charging light would be lit VERY dimly when running/starting fine, but would be unlit when in the non-running mode. So one morning it wouldn't start, I started to think about its electric fuel pump and/or fuel pump relay; relay would've been less expensive, I remember unplugging a harness under the dash which included circuit for fuel pump relay, and I just re-connected it and everything worked fine. So it seems like I also had an intermittent electrical connection, never happened again.