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I had a wild thought, is it possible to your AC compressor with a 12 volt motor so the ac works while engine is off, by a different battery of course.

Just different idea running through my head

I've seen people with converted buses use an AC motor running a small auxiliary air compressor, making 120psi on a battery and inverter. So I don't see why you couldn't run an automotive AC compressor using a house current motor and appropriately sized pure sine wave inverter.

Or at that point, you could just use a stationary AC compressor as from a fridge, sized for the evap/condenser radiators you intend to use. That would be more efficient than a belt driven unit, however it would require more calculations and customizations to build.

Don't forget that the condenser fan and evaporator fan will also have to be running, total of three motors running might be more than a battery/invertor may be capable of handling.

This is the system I'm running in my 53 3100

www.youtube.com/watch?v=mRo05wph2F0

Mick, I'm curious where you mounted the compressor? I assume that you used conventional components for an aftermarket A/C system for your vintage of truck and are using the electric compressor rather than an engine driven one.

Average compressors take 2 - 3 hp to run once spinning, add more HP for initial start, and to be efficient they need to run 1200 or more rpm. Now you need to increase the air flow through the condenser since you won't have the speed of the vehicle to help cool the charge. So add 30 to 40 more amps of power for a big electric condenser fan, 5 or so more for the evap fan, and few more for the clutch. If your system uses the clutch cycling on and off to regulate the temp, now you have to adjust the compressor motor speed as it unloads and loads as the system cycles other wise the rpm will jumping quite a bit. Three group 31, 800 amp batteries should run it for a little while, thats about 250 pounds of batteries.

I haven't installed it yet. The compressor will be mounted under the truck between the frame rails. This unit uses the return gasses to cool the compressor. I have the remote hortazontal mount condenser with a Spal fan that will also mount between the frame rails. I plan on running the lines up from the floor with a false floorboard to hide them. I have the "Old Air" inside kit for my 53 3100. It lets me keep my cowl vent and most of my glove box. I don't see it listed but I have the optional vent that contours across the bottom of the dash. I also have electric P/S to keep my engine compartment looking stock except for maybe the 6-71 blown/nitrous 292. https://www.oldairproducts.com/product/ac-unit-inside-package-ip-4100d?gfid=p112481-c112150

Joe:
I've never looked atone of these compressors, but I can't see why you'd need a clutch. Just turn the motor on and off. Especially if the system had an "unloader valve" like a home A/C system does.

But I don't think Mick groks what you are trying to get across. This system is going to take a LOT of electrical power to get the job done. Power that was (almost) free with a conventional A/C system, like airflow through the condenser and rotating the compressor, is now going to be provided by the alternator which might be as much as 60-70% efficient. The other 30-40% will be engine horsepower turned into heat.

We've had many of those systems tested in our fleet. You are looking for a zero idle unit.

On triple digit days, crews would idle their trucks to keep the AC on. We tested these systems with the fleet to reduce emissions. I think, with the advent of hybrid vehicles, we stopped testing those types of units. But I'm sure most of those companies are still around. The units typically took up the space of a truck bed cross box. Plus the added plumbing to tie in to the OEM system. Here is one company we tested.

A dedicated electric compressor is a whole different game compared to running a normal compreesor with a 12 volt motor. We had electric trucks at work, 5 ton imports converted to electric here in the states. They had a what I would call a refrigerator style compressor, not sure the voltage, but the trucks had 48, 12 volt lithium batteries, 24 on each side to keep them balanced. The A/C was marginal at best, they didn't run them unless it got really hot due to mileage range. The A/C would eat up a lot of miles worth of charge.

If you really want to stay cool, mount a Thermo-King unit in the bed with some duct work to the cab, it would likely cool you with the windows down!