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Military Vehicle A/C system build

andytk5 on Fri January 27, 2012 9:56 PM User is offlineView users profile

Year: 1970
Make: AM General
Model: M35A2
Engine Size: 465
Refrigerant Type: ?
Country of Origin: United States

Hello all!

New guy to the forums and I am in the middle of a restoration of an M35A2 or "deuce and a half" and I will be adding A/C to this truck. I would like a little help in selecting the components to have a properly functioning system. Currently I have a Sanden SD709 12V compressor that has mineral oil or R12 compatible oil that would need to be changed if I went with R134a. I need some help sizing the condenser and selecting the correct hoses and fittings, etc. I have roughly 22"x24" in front of the radiator to work with. The cab is not much bigger than a regular single cab pickup, albeit more "breezy", need to seal up some small holes. Considering some of the smaller universal evap boxes on ebay for around $100 that has just the cooling option, truck has great heat.

Looking into "freeze 12", "ES" or 134a for the system unless there are other options?

Thanks guys!

bohica2xo on Sun January 29, 2012 3:16 AM User is offline

I am familiar with the M35.

First, for any A/C system you need to start with what you need, not what you have laying around. Building a system around a compressor you happen to have only works if it is the compressor you really need.

In this case you need a compressor with a 24v clutch, since the M35 has a 24v electrical system. The only refrigerant that makes any sense for a news system is 134a. So you need a new compressor with a 24v clutch, suitable for use with 134a . The site sponsor, AMA can supply such a compressor. Make sure you order a clutch that has a belt groove compatible with the belts on the M35. You can click on the AMA logo on the top of this page.

Next you will need an evaporator with a 24v fan assembly. The site sponsor actually builds evaporator kits, and will likely be ably to put a 24v fan motor in one for you - Look HERE for their selection of evaporator assemblies.

For the condensor, you want a parallel flow type. There are some universal units available, that will work. For the more or less square openings on older vehicles I have been looking at the condensor from a 2006 CTS-V cadillac. It includes the receiver dryer, so that is one less thing to mount, and two less fittings to leak. It is about 20x24, with peanut fittings.

Stay away from the alternative refrigerants. Nobody will warranty a compressor with them, and there is no need to use them for a new system. 134a is available everywhere, and has been the choice of the OEM's for 15+ years.

You will need to insulate that cab if you want to stay cool. Especially that roof. Dynamat, rigid foam - something. Same goes for the floor. Even a cheap pickup truck has a headliner & carpet or rubber floors. Every square inch of the inside of that cab radiates either driveline heat or solar heat.

Good luck with your project.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

andytk5 on Sun January 29, 2012 4:31 PM User is offlineView users profile

Bohica - Thank you so much for the great information. I appreciate you taking the time to respond to this. I should have mentioned that I added a separate 12V electrical system for my stereo, possible elec radiator fan(Mark VIII fan), and lights etc..

I will be working hard on sealing up and insulating that cab. I already have the floor and rear wall sprayed with bedliner. I will be doing the underhood and engine compartment as well. I should probably make some basic interior panels wood/foam/cloth covered to go on the rear wall, doors, hardtop back/sides/top to insulate as well and cut down on noise. The floor will definitely need some barrier between it and the driveline.

Looking forward to turning a classic into a comfortable ride. Best of both worlds with simplicity and creature comforts.

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