LMTV Air Conditioner

[Kambaku]

Keith, I would be interested in the data from this experiment. If you compare the temps coming out of the vents from the two vehicles without the A/C on what do you get as a reading. Here's why I ask. If I turn on just the fan in my truck whether or not I have it set on recirculate or fresh air, the air coming out is quite hot (I don't have a measurement other than my subjective feel). This is nice in the winter by the way, but it tells me that in the process of cooling the air for air conditioning the temperature differential is quite high. I wish I could give you my temp readings with my A/C on but I currently don't have that data, however what I can say is that mine blows cool air, but also is no where close to what I get out of my Toyota Landcruisers. I'm just wondering if there is so much hot air in that engine compartment that the A/C can only do so much to overcome it?

 

[Keith_J]

Another great point since the lmtv ac evaporator has the heater core regulated by a coolant flow control instead of a blend door. Valves are prone to leaking especially with the engine thermostat closed.

 

[Keith Knight]

I don't think that could be my issue, my reasoning is based on the fact that it can start it early in the morning with a cold engine and cab and it will quickly get to 60 degrees and will stay at that temp even while the the engine is cold the thermostat is closed when the engine is at proper temp and everything is cycling there is no change in the out put AC temp.

What is the expansion valve purpose?

 

[Keith_J]

Thermal expansion valve drops pressure of liquid refrigerant. It prevents ice formation on the evaporator. Systems using fixed orifice tube have an evaporator low pressure cutout on the compressor plus an accumulator to prevent issues.

 

[scottmandu]

I know very little of AC systems. But what makes the difference between my 2003 Jeep Grand Cherokee AC blowing 40 degrees parked right next to my LMTV with a new AC and a condenser at least twice the size, blowing 65 degrees? Both of them in the Florida sun at 90 degrees and 82% humidity. I've also had two different AC shops start from scratch by vacuuming it out then re charging it with the same results.

The LMTV condenser is horribly inefficient, it it large in volume but has a pretty small area exposed to ambient air flow and is in a sub optimal position on the truck. It's also a tube and fin design which is one of the least desirable. A 1/2 thick parallel flow condenser mounted in front of the inter-cooler has more surface area and is about 30-40% more efficient than the stock LMTV condenser.
The Cherokee is insulated better, I'd wager the LMTV windshield is at least twice the area of the Grand Cherokee.

 

[Suprman]

I'm not really an AC guy I don't mind the heat. But I may do AC in my 1088A1. The large trans cooler passenger side behind the cab would probably work well with a big condenser sistered up to it and I could just switch on the existing fans.

 

[mkcoen]

I'm not really an AC guy I don't mind the heat. But I may do AC in my 1088A1. The large trans cooler passenger side behind the cab would probably work well with a big condenser sistered up to it and I could just switch on the existing fans.

Unfortunately down here it's almost a requirement if you want to use your truck in the summer. Heat indexes around San Antonio for the next 10 days are going to be in the 110-115° range. I'm really going to have to insulate the roof also. During the day you can barely touch the roof on the inside without burning your hand.

 

[Keith Knight]

I'm not using the stock condenser though. I'm using one from the humvee kit that is 17"x32"x2.5" and has 4 layers of tubes. With both fans running continuously while the AC is on. Also they are pulling the air through the coils. Mounted behind the cab. Here's a link to more pictures of my AC install. http://www.steelsoldiers.com/showth...Air-Conditioner-Hybrid-Completed-Installation

 

[Another Ahab]

How's the cooling; you serving up ice in the cab!?

 

[bikeracer917]

Does anyone have wiring schematics for the ac system. I know it's pretty cut and dry.... But I need to know about the wiring from the accumulator dryer. My switch on the dryer is 3 pin... Not sure where it connects to. Any help would be greatly appreciated

 

[bikeracer917]

Does anyone have wiring schematics for the ac system? I an not sure where the connection /wiring goes from the accumulator dryer. My switch on the dryer is 3 pin? Any help would be greatly appreciated

 

[mkcoen]

Does anyone have wiring schematics for the ac system? I an not sure where the connection /wiring goes from the accumulator dryer. My switch on the dryer is 3 pin? Any help would be greatly appreciated

Same problem we have. No connection from the wiring kit to the dryer. I have mine at the AC shop right now and I believe they're just going to change the switch out.

 

[bikeracer917]

Hi all. I found a source for the ac compressor. The unit is sanden u-4412. It's right at $320.00 new. If interested I can give you the info

 

[Keith Knight]

How's the cooling; you serving up ice in the cab!?

Not as cold as I was expecting. I'm hoping between all of use when can find a solution.

 

[NDT]

My guess is the BTU ratings between the HMMWV evaporator and the FMTV is too far apart.

 

[mkcoen]

Not as cold as I was expecting. I'm hoping between all of use when can find a solution.

My guess is the BTU ratings between the HMMWV evaporator and the FMTV is too far apart.

Hopefully we'll have a standard setup to measure next week. I have a temp probe from when I bought my M1010 and got the AC working in it so should be able to gauge temps right at the vent. I still haven't heard back from the shop yet. I'll head down in the morning to rattle their cage if no word by 1700.

 

[Keith Knight]

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.
Hope this helps.

 

[NDT]

My guess is the reason the gen 2 evaporator is so much physically larger than the gen 1 is because it has a lot more BTU capacity as apparently was needed for Iraq. So if you are using the gen 1 evap with high capacity other components, there is your mismatch.

 

[tburk49760]

Well now I'm wondering if I have a gen one or two condenser??

 

[bikeracer917]

Hi. If you haven't found the pulley yet... Call Ringpower corp. They are a caterpillar dealer. I found one for my c7 for only $188.00