Aftermarket AC in factory AC 71

[sKnNyPpY]

Hey guys I believe the switch is out on my AC on my 71 GMC. It was a factory air truck but I believe the PO switched it out. It was working fine until the fan speed switch got hard to turn on/change speed. While checking connections on the switch it did spark (while running). While looking for the relay/resistors mentioned in other ac posts I found some discrepancies to original and would like some help IDing what I have. The relay seems to be relocated next to the fuse box, and there is a knob on the heater box that I don't know the function of. Thanks!

compressor:




under hood:


heater box knob-what is this?:


heater box:

[sKnNyPpY]

pics of relay by fuse box no markings OOPS is this the horn relay?:


control panel:

[67ChevyRedneck]

That's an older vintage air kit.

The knob is the thermostat for the A/C.

You can order a new fan speed switch from any parts vendor for these trucks (you're referring to the one on the dash control panel, right?) Those switches do wear out.

Here's the install instructions for that kit. Page 8 and 9 have your thermostat.

http://vintageair.com/DownloadsSecti...ols)%20Ine.pdf

[sKnNyPpY]

Thanks for the ID 67ChevyRedneck! I'm probably gonna order the switch from GMC Pauls today (yea the one on the dash). Do you know if this system uses the resistors and relays like the factory or not?

[67ChevyRedneck]

No, it uses it's own "stand alone" harness. It does use two 4 prong relays. They should be somewhere under the dash (see wiring diagram on page 8 of link I posted earlier). Look for wires under dash, the relays will be somewhere hanging off of those.

I have pics of some of the wiring here:

http://www.67-72chevytrucks.com/vboa...=249479&page=3

[sKnNyPpY]

AWESOME write up on your AC install. I'm so glad the PO went through all that for me

[67ChevyRedneck]

It's really not hard. I just installed another vintage air kit on my 65 mustang last summer. If I didn't clean/paint things as I went, I could have had it done and working in one weekend.

I lived in Lexington years ago, I don't know how anyone could live there, it's a lot hotter there than here in the upstate. I used to live near where old Charleston road and Platt springs road crossed.