Technical Installing Remote Condensor For Trunk Air Conditioner

I want to install a Vintage Air trunk unit in my 1937 LaSalle along with a 12V 3HP DC motor to run the compressor, so I don't have to mount it on the engine. I spoke with a man who has 'sold thousands of DC motors to make 'Mexican air conditioners". He says many are mounting a condensor under the gas tank, then the unit as I describe in the trunk. I wondered if enough air would pass through the condensor unit to make it work. I notice on the Vintage Air website they do make a remote condensor, complete with fan and a notice that the unit is not designed to be used as the primary condensor. Thus I'm seeking suggestions as how to accomplish my goals as described. I don't want the compressor on the engine nor the unit under my dash. I'm concerned about the condensor for now and wondering which size to buy.

 

Some years ago we built a 56 Nomad with a full size vintage air condenser under the rear of the car with a large elec fan. It worked fine but was a pain to install and suseptable to damage

 

I have nothing really to add other than I’d love to see how this project goes. I’ve often thought about using an electric motor to drive the compressor or even an electric compressor itself.

Please keep us posted with this one


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You're going to need around 180 amps to run a 3hp 12vdc motor...

 

I gave considerable thought to the remote condenser idea a few years ago. I even bought a remote condenser and tried several locations on a 38 Ford sedan. The best option I found but did not follow through with was in the rear fender well behind the tire. I was concerned that it would get too much debris thrown at it in that location all other areas I tried did not seem to have enough room for air flow. I eventually went with the conventional condenser location in front of the radiator. 180 amps! That's a lot of juice!

Another local guy mounted the remote condenser behind the drivers side front tire on his 39 Standard coupe. He said it worked okay. Good luck with your project. It will be interesting to see how you accomplish your goal.

 

I think that the weak spot will be the remote condenser. I originally used one on my 53 F100 but it never worked well. Removed it and went to front of the radiator mount and now it will freeze you out of the cab. Have a friend with one on his 39 Ford and is getting ready to change it soon, it has never cooled well. After riding in my 40 and experiencing a good working Vintage Air unit he realizes his could be cool also.

 

We put a remote condenser under the back of my brothers Model A sedan. It has its own fan and shroud. Seems to work good. Kind of hard to tell since the car runs a bit on the warm side so he can't drive it in traffic for long.

 

FYI, you should look into electrically driven AC compressors that are already available as one complete unit. They are used on boats, RVs, hybrid and electric cars, some 18 wheelers, etc. and are readily available, so you don't have to fab up your own rig to do just what you want. They don't draw as many amps as you might think, either. I did the research a few years ago in order to put it in a vintage car that I didn't want to modify the engine compartment on. Just bolt it in, wire it and plumb the lines. Yer done.

 

I found a unit that puts out 180 at idle, 280 total.

 

A friend of mine had a air cooled VW that had a dealer add in AC, the condenser mounted in the gap between the front sheet metal and the front axle. It had two small fans on it. She said it cooled pretty good until a rock put a hole in the condenser and she never had it fixed.

 

I looked into those months ago, and will do so again. I found the prices all over the map, found everything from one that looks absolutely industrial to ones off Toyota's, etc. Awfully confusing, but some of them have to work well.

 

Here's an article on the Vintage Air website about electrically operated air conditioning systems, with reasons why they don't recommend them: https://www.vintageair.com/tech-topic-is-an-electric-compressor-a-good-option-for-my-hot-rod/

Note that some electric a/c systems run at something other than 12vdc - marine equipment is often 24vdc which would cut the amps in half, and electric vehicles may run them at even higher voltages like 48vdc; that would cut the amps to 25% of what is required at 12vdc.

 

Well, here is n electric powered compressor that will get the job done the only issue is that it is 2080 in US dollars at the moment but is marketed to the vintage Porsche owners market. https://www.classicretrofit.com/col...ng/products/electrocooler-compressor-ecu-only

 

Large trucks run electric AC units for a bunk cooler. However, you must run the engine driven AC to cool the cab and the electric unit in the bunk will just maintain temperature overnight without running the engine. They have a condenser mounted on the back of the cab.

 

Dont know what youre running for a rearend. 9" fords have yokes with pulleys mainly for running cooling pumps. Could be used to drive a compressor. Pulley ratio would need to be figured out.

 

We had some company trucks with that setup. The Bunk AC ran off a bank of 3 or 4 minimum 1000 CCA batteries. You had to have the truck cool with the cab air, and the division curtain closed when you shut down the Diesel engine. Even at that, it would only work 6 to 8 hours, and those last couple of hours were just minimal cooling. A good idea that wasn’t as good in the real world as it was on paper. The next batch of trucks they bought they went back to either the small two cylinder auxiliary power plants to run the AC, or just kept the truck running. The idea was fuel savings, which they did, but the return on investment would have taken several more years than they would have owned the trucks.

 

This is going to be interesting...........

 

That's what I was thinking. Also about being succeptable to damage from road hazards and likely will need a big shrouded fan mounted on condenser. About like running a starter motor full time to operate compressor. But with that said it will not have quite as much load turning a Sanden compressor compared to cranking an engine.
I know many of the early cars with factory air had trunk units & from riding in some of those back in the early 50's I remember that they were cooling in reverse. Front mount evaporator under dash cools front seat area first and a trunk mount cools rear first. If you use something like those big plastic tubes mounted on rear shelf they tend to direct cool air flow near the headliner to front of car and that works well for front seat but not much for rear seat. As a teen ager back in early 50's I remember riding in back seat of early 50's Olds with that set up and was sweating bac there with all the air directed overhead to front.
Sometime this month I will be ordering a heat, cool, defrost Vintage Air slimline unit that will all fit below the dash, not up and behind the dash. The ones that tuck up behind the dash as hidden units will not work in my 50 Plymouth because of that HUGE radio. It all has to be below the dash. As it is a 4 door I do not think the trunk mount evaporator would be very efficient.
A comment on Vintage Airs comment about a radiator mount condenser not meant for remote unit my thought is there would be too much distance between it and evaporator and you would not get a good flash point near evaporator for good cooling.
With a trunk evaporator make sure you have a large enough drain tube.
Keep s posted on how this all goes.
Jimie

 

In terms of the compressor, are we overthinking the problem? Surplus Center lists a 2hp 110/220v air compressor motor, 3450 rpm for $148. 15A at 110v is only like 1750 watts continuous. You could easily get a 3000/6000 watt power inverter and just run the compressor on household 110v instead of 12v.

Even simpler, a quick google search shows the Denso A/C compressor from the 2005 Prius uses only 17A at 12v. So there is really no reason you couldn't make this work.

 

I DID come across the Denso from the 2005 Prius and looking into it now. I have no
real knowledge of the power inverters, so of course trying to make it all as simple as I can. Now I'm concerned about installing the condenser (under the gas tank) and wondering if it will work very well. Since I have the body off, now's the time to do it.
Thanks for the advice.

 

For now I have a stock rear end, but was considering a pulley on a rear end and sure glad you informed me about the Ford. Thanks.

 

FWIW, I would never install a condenser under the gas tank. For myself, that would be basically installing the condenser on the ground and using it as a skid plate. If you want to hide it that badly, mount it in the trunk under the package tray, shrouds it and close a pull through fan to duct to the exterior of the vehicle through the trunk floor, you could vent the trunk for fresh air in as well. The trunk of that car is huge, use that to your advantage

 

From your other thread, a year ago....

I suggest you put the compressor under the hood, driven by the engine, with a belt. Then you can put the condenser in front of the radiator, where it will get plenty of cool air, and make use of the engine cooling fan, so no extra fan will be needed. And you'll still have all your trunk space. This setup has been proven to work on billions of cars.

 

^^^^ This...

You're chasing a Unicorn. If you're willing to fill the trunk with batteries/electronics, you may be able to make it work, and I'd suggest getting a professional engineer involved so you don't burn your car down but you'll spend far more money for a system that will be iffy at best.

First, starting current inrush will be at least 300% of the running current. Invertors generally don't like motor loads either, especially when close to their max output. They also generate a lot of heat that you'll have to deal with. Second, you'll be running some very large cables with very high currents in them and the usual automotive fusing methods and cheating on wire size won't be adequate for safety. You'll need major upgrades to the car's wiring harness.

And that Denso compressor either draws more amps or runs at more than 12 volts. That's only a bit over 1/4 HP at best, nowhere near enough to run a compressor of any size unless all you're planning on cooling is a lunchbox. Most electric vehicles run at 400 volts or more, there's less '12 volt' stuff than you think.

 

I run a vintage air unit behind the seat ,under the package shelf on my 1940 ford .condenser and compressor under the hood,it will pull the cab temp down to 39 at the duct , and keep the cab at 55 all day on medium fan. Plus my car leaks air around the doors. And ain't no clutter under the dash. Listen to your squirrel !!!

 

Not if he pulls 3 phase off the alternator. I would never go DC with this.. The alternator is all ready ac..

 

power is power...it doesn't matter if it's a rotating shaft, single phase AC, three phase AC, DC at low voltage, DC at high voltage, etc. 3hp is about 2300 watts, and 2300w/12v is close to 200 amps.

 

.... And that doesn't include starting current inrush.

 

The more I read this the more trouble and expense it seems to being just to not have a compressor on the engine so a few people won't piss and moan about it being there.

Paint the thing satin black engine accessory color or engine color and mount it low and no one will pay much attention anyhow.

 

Mounting the condenser flat under the gas tank won’t work the condenser needs to be vertical hot vapor in the top liquid out the bottom . the bottom fourth adding further sub cooling . Running an electric compressor has to have some means of unloading or it stops and starts continuously which overheats the windings . Besides building your electrical power supply you’ll also have to design the refrigeration system . This sounds like a real challenging project . I can’t wait to see how it comes out .