AC on my 2004 Silverado

[bigd65]

I got in my truck at work and the AC stopped blowing on the #4 setting. I just replaced the HIGH speed resistor. Is this my control panel going out... works on all other settings.

[bigd65]

Anyone?.. those control panels are not cheap. I don't want to just throw parts at it

[hatzie]

The squarebody blower HI position bypasses the resistor.

I'll look in my service manual for the wiring diagram.
I assume you don't have the digital climate control head.

[bigd65]

No sir,not digital... has the two knobs. Left for fans speed, right is for level adjustments. Then the two center are for temp control on either side

[hatzie]

Supposedly there's a Blower relay that energizes when the switch is set to HI
When the relay is not energized the blower gets power from the resistor pak
When the relay is energized it gets power directly from the blower fuse

[hatzie]

Ground G200 is a straight up stud under the top cover of the dash back near the windshield. All kinds of fun to reach. Since the blower motor works on L & Med settings I'd guess this ground is just fine.

The blower resistor includes the HI speed fan relay.

Check the 40A Blower fuse in the engine compartment fuse/relay panel has power with the ignition switched on. The diagram calls the L-BEC "Junction Block I/P".
Check the RED wire into the blower resistor/relay pak and check the disconnect at the L-BEC behind the LH dash fuse panel.
Check the orange wire from the blower switch to the resistor pak with the blower switched to HI.