FMTV Air Conditioner Hybrid Completed Installation

Sounds like you have low refrigerant or an expansion valve issue. What are your pressures? Also how many pounds of Freon did you put in the system?

Hi. Does anyone know the wiring for the fording switch? It is the single wire in the cab unit and goes to the pressure switch on the hose at the receiver dryer.... But where does the other lead connect? I have a schematic but it doesn't show the one lead.

The amount of refrigerant is relative to the size of the system. First taking it to a local shop that put 8 lbs in it and not being satisfied with the results. I contacted red dot who felt that was to much and recommended a specialty AC shop 70 miles away in Tampa which specializes in custom AC installations for over 30 years. I took it there and they vacuumed the the system and started from scratch and watched the pressures while filling the system back up and put the same amount back into it within a few ounces and he was very pleased with the pressures and called it perfect.
Unfortunately I don't know the symptoms of a bad expansion valve.

Keith Knight said:

The amount of refrigerant is relative to the size of the system. First taking it to a local shop that put 8 lbs in it and not being satisfied with the results. I contacted red dot who felt that was to much and recommended a specialty AC shop 70 miles away in Tampa which specializes in custom AC installations for over 30 years. I took it there and they vacuumed the the system and started from scratch and watched the pressures while filling the system back up and put the same amount back into it within a few ounces and he was very pleased with the pressures and called it perfect.
Unfortunately I don't know the symptoms of a bad expansion valve.

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8 lbs? That seems way high. Semi tractors take 3 ish pounds.. My thermo King refrigeration unit takes 6 lbs and it's a 150,000 btu unit that can cool a 53 foot insulated trailer to -10c.

Could you give any input on wiring for the single wire that connects to the pressure switch on the hose at the receiver dryer that is used for fording?

I'll try to help out with the wiring but understand that this is based on my Gen1 Evaporator unit and that you should only do this if you are qualified and fully understand the system. Don't take what I say as fact for all circumstances as yours may be different and you should always verify you wiring before starting.
Wiring diagrams are located in this forum at post #92 for Gen2 and post #134 for Gen1.

Drier: Mine is a 2 switch style, one switch for the High Pressure switch the other one is for the Fan Cycling switch each switch is a two wire switch and are normaly open type.
Each switch requires a ground that is not shown in the diagram so I added it in.
The fan cycling switch can be ran through the fording/engine fan off switch in the dash so it would be turned off with that switch when fording.
After testing I decided to wire the fans to run continuously while the AC is on in an attempt to get it to run as cold as possible. I just wired the Black wire #1 to a ground.


NOTE: The wire labeled "TO FAN CYCLING PRESSURE SWITCH/FORDING SWITCH" Which should be a Black wire stamped with a #1.
This wire controls the condenser fans, when this wire connects to ground it activates the condenser fan relay inside the evaporator unit.
You can wire it up in a few different ways;
1: Permanently connect the wire to ground which will make the condenser fans run continuously while the A/C is on.
2: Run the wire to the Fan cycling pressure switch on the drier (that pressure being a two wire switch, will also require a ground wire) this method cycles the fans on and off accordingly.
3: You could wire it to a self installed toggle switch so you could turn it OFF while fording and ON like example #1
4: Figure out the factory fording switch and wire it through it so its on a normally closed circuit, then wire it to the pressure switch so the fans can cycle accordingly and be turned off when fording.
5: Same as #4 but instead of using the factory fording switch install your own toggle switch.
It all depends on how involved you want to get with it.

Hope this helps

How is your system working now?

With your splash guards modified, do you get more mud/crud in the engine compartment? Do you have pictures of how much coverage you have now with the cab down?


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Where in Tampa? I have a 93 M998 HMMWV i want to put AC into.

I haven't seen any additional mud or such get into the engine compartment.

I'm in Wauchula.

What was the name of the shop Red Dot recomended in Tampa? I was considering puting one in my HMMWV. Do you know much about Red Dot?

Keith Knight said:

I haven't seen any additional mud or such get into the engine compartment.

I'm in Wauchula.

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Do you mind taking a picture of it with the cab down? I would really appreciate it.


I would like to see what it looks like.

Thanks!


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This is on my list for the new truck, currently collecting parts.

Here are a couple pictures with the cab down.

Keith Knight said:

Here are a couple pictures with the cab down.
View attachment 662461View attachment 662462

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Everything looks brand-spanking new; like it was sitting on a showroom floor. That's nice.

I believe I've got a couple of the replacement center consoles with the a/c controls if you can't find any.

Dave

pm sent

SPAL va18-bp70/ll-41ms 24V FAN , CNFP1623KT Kit AC A/C Universal Condenser Parallel Flow 16 x 23 O-ring with Drier
Her are a couple changes I've made that has improved the temp coming out of the vent, it dropped the temp from 60-65 down to 48-52 degrees and much cheaper way to go. I purchased both thing fro the famous auction site.
The old tube and fine style condenser is way out dated and not very efficient so I changed to the modern parallel flow design used in modern vehicles which is smaller, lighter and more efficient the condenser was only about $50 the fan was about the same price then you have to figure out how you want to mount it.

Red Dot makes universal hose supplies that you cut yourself and put the fittings on yourself which make it real easy. Do a quick google search for Red Dot Ez clips view images and you'll see what I'm talking about.

I also redesigned the air vents so you can control the direction of air flow instead of the original design which could blow air any lower than the top of my head (yes I'm short only 5"5") but now I can direct air flow to any part of my body minus my feet.


Yes I painted it Black after the photo.

Nice work, Keith!

Good call parallel flow condensers are up to 40% more efficient than tube and fin. When I replaced the old outdated Red Dot tube and fin condenser in our A/C kits with a parallel flow unit, we saw an 18% decrease in condenser outlet temps, and a 10% decrease in evaporator temps.

The condenser will work on Gen 1 or 2.