As I am trying to fix my fridge before I have to get a new one, I thought about the way a fridge works and wonder about using that idea in a car. I know it would take some figuring out but the compressor is smaller and could be less draw on the engine? Has anyone thought about trying this? It is just an idea and I don’t think I have the electrical knowledge to try it.

Fridges use very little compressors, condensers, & evaporators since the air barely circulates and is in a sealed box. Often the circulation inside the fridge is simply convection currents of hot cold air rising & falling. No fan inside at all.

As you increase the size of the box, i.e. Fridge, car, house, store, stadium, more air has to circulate to cool the area.

Small compressors & evaporators will not effectively cool air fast enough to be force blown across the evaporator and through the "box", so the sizing has to increase.

Combine that with the lack of insulation / greenhouse effect of glass windows in cars the size required to cool an area increases.

I believe that an electric AC unit in a car would work. It could be driven by electricity from an alternator and be more efficient BUT it would cost more to produce because while there would be a decrease in AC component costs it would require a sizable increase in electrical capacity and some modifications to the charge system to power the unit at idle. Car companies go for cheap.

I had toyed with the idea of using peltier coolers on a water cooled plate but got sidetracked. It could be a fully contained electric cooler (like they use in micro electric fridges) but I'm sure if it was feasible it would already be done by somebody smarter than I.

Yours is a good idea though, a compressor from a small window unit AC might be the best choice over fridge unit.

Modern all-electric and hybrid cars don't have an engine-driven compressor, so the A/C power is all-electric. Why couldn't the system be retrofit into an older car?

https://www.priusonline.com/threads/how-does-the-electric-a-c-compressor-work.18169/

a guy asks in this thread about retrofitting.

https://www.cruisencomfortusa.com/hot-rod-series-1

or this

i was thinking about this [https://www.cruisencomfortusa.com/hot-rod-series-1] as well.
i didn't click on the "purchase now" button, but if i remember when this was introduced a couple of years ago, it wasn't exactly moderately priced.
however, in certain applications, it may be the best option. i have never been around anyone that has installed one of these kits, so i have no idea if they work reasonably well or not.

A window unit would definitely be easier to convert and cheaper probably. Those that have the knobs still would help.

I just replaced the compressor on an 07 Civic hybrid. it is both engine drive and electrically driven, depending on what mode it is operating in. The compressor is also not cheap.

You had better have a healthy system before installing one of them. 38-46 amps nominal @ 12 Volts

I have often looked at the PTO option on some of the 1994+ 2500/3500 Dodge Ram trucks and thought something like:

“If I had one of those PTO’s hooked to a 3 phase 120/240 generator,
I would not only have a portable electrical generator station,
I would also have a “DYNO” to test the engine fuel economy at various % throttle and rpms.
Just generate and measure the electrical power fed to a resistance heater.
I could predict ahead of time what MPG could be got with various gear ratios, because I can calculate aerodynamic and tire rolling resistance power.

Reading this post I can now add:
You could add more air conditioning options for the truck cab too.
Use the PTO/generator to supply power
to one of the “portable room air conditioners” with a single hot air outlet house.
(drain the condensate water through the floor of the truck cab.)

Another factor to consider:
if the portable air conditioner developed a fault,
quickly swap it out as a module.

Wouldn’t it be interesting if each “system” in a truck/car
was a “quick swap module” if it was not too expensive?

The Hubble Space Telescope is a collection of modules
( except for the faulty Perkins-Elmer built main reflecting mirror,
which should have been instead the correctly polished Corning Glass Company mirror, which NASA bought, paid for, and put in a warehouse... no kidding)

I have experience using a portable 120 volt a/c unit to cool a large machine cab. The hydraulic driven air conditioner was in a back corner and did not blow any air on the operator. The machine had a large generator and a 120 volt outlet in the cab. The portable a/c unit made all the difference. No more complaints from the operator! Also the portable a/c required no maintenance. I can't say the same for the hydraulic unit.

absolutely ! it would be interesting to see the installation sheet for this, and if they mention a minimum alternator size needed, as well as any needed mods to the electrical system.

More than that if you want any sort of cooling performance. I think my portable 12,000 BTU unit at home is rated at 10 or 12 amps running. That means 100-120 amps at 12v.

It's what we use in a lot of Cessna aircraft. Looks just like an automotive rotary pump driven by an electric motor. Both mounted on an aluminum pallet. Super simple.

I wonder if one could use a starter motor to drive a rotary compressor for a cheap equivalent?

A starter isn't made to do that sort of duty cycle. I think it would overheat and/or eat brushes.

Substantially less load though. Might be an interesting experiment, if I had a spare compressor and starter to us.