Who Has A Unmolested 72 w/ Factory A/C?

[AncientOrange]

I have a 72 Custom Camper with factory A/C that I need some wiring help with. I need to know where the 12V feed for the high speed blower relay should be plugged in to the fuse box. On my truck, when I got it, it was plugged in where I have circled in yellow and I keep blowing the 15A fuse labled GL BOX SPOT LP circled in red. Circled in blue are some terminals labled IGN UNFUSED I could plug it into, but the unfused part has me concerned as I haven't found the 30A inline fuse I'm used to seeing on GM Vehicles for the high speed blower. Where should this feed be plugged in?

[Aarons72s]

It goes into the cigarrete lighter port on a 72. It is sopposed to be un fused. hope this helps.

[AncientOrange]

Originally Posted by Aarons72s

It goes into the cigarrete lighter port on a 72. It is sopposed to be un fused. hope this helps.

TIA

[Hutch]

AncientOrange

The above post was correct.
This Diagram shows it plugged into the receptacle CIG

[AncientOrange]

Thanks and I'm curious what book that schematic came out of. That helps a bunch. The only schematic I have is out of a Haynes manual and it doesn't show the H/S blower relay at all. I saved that pic.

Also interenting where it says to replace the existing heater fuse with a 25A fuse. I'm guessing that must source and protect the cig lighter and H/S blower tap.

I've been fighting this problem for a while now. I just replaced the H/S blower relay after finally figuring out where GM hid that on this truck.

Thanks again for everyone's help.

[ChevyMex]

67 - 72 Chevrolet truck factory manual

[Huck]

One real common problem on the A/C trucks is the gound for the A/C fan motor relay that mounts on the side of the heater box behind the glove box. You loose low speeds on the fan if this gound is not solid so while there----.

[mrein3]

One thing that is certain on these trucks is the wiring from the factory is not very good. The headlight switch and the high-speed fan are two good examples.

When I converted from non-AC to AC I fixed the high speed fan thing.

I ran a 10 gauge wire from the battery, through a 20 amp in-line fuse, to the business side of a 30 amp relay. Now I get a clean, 12-14 amps for the high speed fan, and I don't have any burnt connectors like the connector behind the fan switch or the red wire shown in photo #1 above.

I've never seen a truck in the yard that didn't have both of the above connectors partially or fully melted.

This mod, and the headlight switch relays are two REALLY good mods to do if you are interested in fixing these items only once.