FMTV Air Conditioner Hybrid Completed Installation

The Plan: Take a readily available Humvee AC kit, Red Dot PN# RD-2-5497-0, NSN:4120-01-581-9451, Contract CAGE: 31UG4
Note: I found my kit at the auction site we all love.


and the FMTV Interior AC unit (Evaporator-Heater Assembly) 1st generation Red Dot PN# R-5750-1

Combine them to make a fully functional Air conditioner for my 2003 M1078A1 with the 3126B engine before the Florida summer heat gets here.

Don't get me wrong, I wanted to collect all the factory original parts to do it but doing so looked like a more difficult (meaning finding all the separate parts not the installation) and long process.

After having the Humvee kit and the AC unit side by side I was able to verify this could be done with some rewiring and some custom brackets.

Being a Prototype Engineer with my own machine shop, I set out to design and fabricate the brackets and pulley necessary for a clean installation that should allow the DIY guys the opportunity to have a working AC in there FMTV's. Noterilling, welding, and machining the generator pulley are required.

Here is what it looks like installed.


The Compressor (SanDen model# U4311) is mounted using the Red Dot AC universal adaptor mount kit 75R 6010 / RD-5-5032 to the custom steel bracket that is welded to the generator mount. To do the welding the generator and generator bracket were removed. I also made some custom bushings that allow for a better fit of the compressor to the universal mount. instead of just using the stacked washers that came with the kit.

The Generator Pulley was removed and machined to fit the new v-grove pulley.

The Condenser is mounted to the round tube by drilling two 1/2" holes for the two 1/2" bolts. The angle support is mounted to the existing welded loop on the tire support tube, no drilling required for that. Drilling some 5/16" holes in the condenser for the mounts would be required and some minor trimming of some sheet metal around the AC line connectors. All of the custom brackets for the condenser are made of aluminum.


The Drier is mounted using a custom aluminum bracket mounted to the frame using existing holes in the frame. No drilling required.




The interior AC unit has 4 holes that require drilling through the floor, 2 for the high and low AC lines and 2 for the drains. The two for the AC lines are shown with the two circles with the dot in the middle. I found the best fit was to put the low pressure line closest to the windshield. To ensure the best fit for the drain holes, make a template (using some paper or cardboard) of the bottom of your AC unit and then match it up with the mounting holes in the floor.
The electrical lines were routed through an existing hole made for wires to go through.



The Engine Skirt was moved out in order to miss the compressor using custom aluminum spacers. Drilling out the rivets holding the skirt on and drilling holes in the aluminum spacers to match the skirt and mount would be necessary.

The AC lines, fill ports, connectors, crimpers etc all "should" come in the humvee kit and was pretty straight forward making the lines.

The Electric requires splicing wires from the humvee harness into the interior AC harness. The new interior AC unit requires two 24v power supplies and one 12v power supply. After removing the old heater it leaves one 24v power supply for the blower and one 12v power supply for the lights. So you only need to find one 24v power supply for the condenser off of the fuse panel. I wired it to a spare fuse that wasn't being used and put a 25amp fuse in it.

Final step find a qualified AC specialist to charge the system. Now we have 50-60 degree air conditioning at the vent depending on the out side temperature.

Note:
This is on a M1078A1 with a 3126 engine that has the serpentine belt
My humvee kit did not have the the universal compressor mount, I've been told that it should have.
To make this work on a M1078 with the 3116 engine a similar but different custom bracket I would need to designed a new bracket for welding to the generator bracket for the compressor mount. As the 3116 generator mount is different than the 3126 mount.


Now I can enjoy driving it this summer!

If I get enough serious interests I would consider building some sort of bracket and hardware kit to make your humvee kit and interior AC unit installation as easy as possible for those interested.

I hope this makes sense to everyone. I'll go back over it later and make changes to any mistakes I catch.

Keith,

Thanks for the write up. Unfortunately I can't get any of the attachments to open. Hopefully it's just my system.

Edit: ok got them now

On a side note, there used to be a great butcher shop in Wauchula back in the '70s. They had this steak seasoning called "Monkey Dust" that was awesome. Just thinking about it makes me hungry.

Ok, how much for a set of brackets ? You know you wanted to go into business ? LOL

Like where you mounted the condenser .

And since you have the capabilities, could you fab some condenser brackets designed to fit in the stock AC condenser location?

If 5-10 seriously interested people contact me I could start putting a price on it.
Also I would need someone interested close enough to me to bring there FMTV over for a week so I could design build a bracket for the 3116 generator mount.

Why is every body on the other coast !

I have a Red Dot kit (HMMWV) in storage I would love to use on my LMTV with the 3116 motor. Let me know how much for a kit.

Whoever is seriously interested, send me a personal message with all your contact information and I'll start putting a list together.
Be sure to include what year and what engine yours is.

Keith Knight said:

Whoever is seriously interested, send me an e-mail with all your contact information and I'll start putting a list together.

Click to expand...

done

PM sent !

Outstanding Job, Keith

I think Keith's idea of mounting the condenser up high and out of the way is very interesting and will certainly solve the problem of having it up front like the factory install. Attached are three images of how I found the condenser in my truck and the front of the radiator. The fan unit and front surface of the condenser was plugged up with hard caked on mud and sand and it took me hours to clean it. I had an issue with my A/C not working so I decided to pull the entire unit out and you can see in the second photo how I found the back of the condenser. I also found the radiator fins (third image) in the same condition as the condenser. There is no way that you can see this unless you loosen up the condenser brackets and swing it out. It goes without saying that both the condenser and the radiator behind it were severely compromised. It took me 10 hours of work to clean them both. I eventually installed a new fan unit. Everything is now working fine.

There are a couple lessons here: 1) if you're going to mount it up front like the original install you have to check it periodically for debris., 2) if you're going to do any fording you should also take the time to make sure that both the condenser and the radiator are cleaned out while any mud, sand and debris maybe loose. I spent a considerable amount of time cleaning up my entire system because everything was hard-packed and dry.

I think Keith's idea of mounting the condenser up and out of the way should be considered.

Nice work and thanks for sharing.

Dave

Kambaku, if you decide to move your condenser could you take photos and detailed measurements of the brackets? I've been looking for a set for a while and looks like I'll need to make my own.

There are really 2 "brackets", or more properly stated sets of brackets. There are 2 large brackets that attach to what I will simply call the front frame rails. These are heavy metal brackets. In addition, there are 4 separate "L" shaped brackets that attach to the front of the condenser's fan unit that actually hold both the condenser itself and the fan unit to the aforementioned larger brackets.

This may be a little confusing if you have not looked closely at the setup. Can you tell me what brackets you are referring to, or is it the entire set up. The little "L" brackets are the easiest to manufacture.

I can now see from the photo that you posted that the brackets in that image are much different than what is on my truck.

Kambaku said:

This may be a little confusing if you have not looked closely at the setup. Can you tell me what brackets you are referring to, or is it the entire set up. The little "L" brackets are the easiest to manufacture.

Click to expand...

Yes I need the whole setup.

You can see from this image what I am referring to if you compare it to the posted image on the thread. The brackets are different. This is my new fan unit and nice clean condenser.

Kambaku said:

You can see from this image what I am referring to if you compare it to the posted image on the thread. The brackets are different. This is my new fan unit and nice clean condenser.

View attachment 622572

Click to expand...

Definitely a different style of brackets and one that looks a lot easier to replicate than the ones in my photo (difference between an A0 and A1 maybe?). Guess I'll just see how it looks when I can finally touch my truck (now that it's running - YAY!) and compare it to the new condenser.

I haven't done it from scratch, however I don't think it would be too difficult to fabricate some brackets to hold it in that spot if that is your intention. I compared the size of my condenser's width to one that is being sold on eBay and the latter is only about 3/4" narrower. Being smaller is good because you can fabricate a bracket to make it work. Suggest you get your truck and parts in hand and go from there.