Automotive Air Conditioning Information Forum

Here is the front evap and heater core, and shown in place, then the plenum that goes across the dash attaches to the evap ass.
Not allot of good pictures out there.

The rear evap sits on the floor (elbow high to passenger) between the rear seats, I hope to invert the evap in that housing so I can flip it and mount it to the ceiling.
I also may use an aftermarket rear evep if the factory one gets to be a big hassle, not going to be dropping shell casings on or standing on it so it does not need to be so heavy.
But I need that area between the read seats to be able to be able to lay in the back

The front system looks like it probably does the job, and is well integrated with the vehicle. A 4 port heater core bypass to keep the hot water out of the cockpit is probably on the vehicle someplace - if not add one.

The condensers look solid. Can you put fans on the second condenser?

The rear evaporator looks suspiciously like a small underdash unit in a steel box. That we can upgrade easily

https://www.ackits.com/evap-assy-minibu ... ch=30-0122

I have seen this unit mounted at the rear ceiling of shuttle busses several times. Basically a double width version of what is in that box, with 2 blower motors and 4 fan wheels. Ready to mount underneath a surface. And available from the site sponsor.

One of the Condensers had the fans removed, they both have two fans each, I wish I had bought these when they were available, seems like every time I actually get ready to do something everything is more expensive and harder to find.
I have seen that evap before IIRC the controls can be remotely mounted which I would not use anyway, that price is the best I have seen though.
The M1151A1 had an electric heater valve, I will use the cable controlled valve already on my M998A1
Many that have the M1151A1 style AC units (there are several models very similar) convert to the manual valve to mix in some heat due to the lack of a thermostat controlled compressor.
They probably do not live in S TX
I wonder if that evap has an expansion valve?

This truck has no doors or rear "curtain" at this time, one of my other HMMWV has a fiberglass top and no AC and driving in in the summer is brutal/actually dangerous so I generally do not use it in the summer.
So the actual plan is to install the AC system without the rear evap to make sure everything goes together OK, then adding the rear evap after the roof and doors are added, at least at that time I will have the front evap working.
That aftermarket evap looks good, I did find the specs and it does come with an expansion valve, the only down side is I can install 90 degree vents on the stock unit to blow down onto the rear passengers as the evap will be pretty much directly above the passengers.

Yes that evaporator has an expansion valve, and has O ring ports. It is 27 inches wide and 5.75 inches thick

The vents will direct downward, not straight down but they do blow at the seats in a van. Cold air falls pretty well.

I think you will want the remote fan control. With a rear TXV you shut down the airflow and it goes to minimum flow. It still keeps the oil returning in the system when the rear cooling is not in use.

There are a lot of electric fan choices out there today for condenser fans.

I would build the whole system and work out the charge, rather than do it twice.

I seriously doubt the rear air would ever be shut down.
Considering the massive amount of labor involved with cutting out the rear fenders and fitting the condensers and almost as much labor removing the original heater apparatus and installing the front evap filling the system twice is a walk in the park.

It is hard to explain to someone that has not worked on a HMMWV how difficult everything is, I have been twisting wrenches for over 50 years and have never seen anything like it.

It took me 7 months to shoehorn the Duramax into this machine, I did have a job at the time (retired now) and worked in my spare time but still it is defiantly 10lb of crap stuffed into a 5lb bag

They even run all the AC wiring and hoses on the inside of the cab because the way the frame/body is fit there is virtually no place to run anything underneath the truck.
It is completely its own species
Sorry, not enough room to add a decent picture

You should buy a Saracen Mk6. Working on it will make you love your H1's

That looks like it could be a chore to work on!
How about a suction side low pressure switch? not allot of aftermarket stuff I see uses it but it is quite common in the automotive ind.
Does the low pressure switch in the trinary switch take its place?

A trinary switch monitors the high and low limits only on the high side of the system, and it also controls the fan(s).