M923 air conditioning a/c install project

[Hawssie]

Thats a point I can understand with the fan only coming on intermittently and only based on coolant temp. .The military did use some radiator mounted condensers latley in at least some of the Mraps. I bought a few complete core supports with inner coolers and condensers etc but they were built with a stack of 2 condensers, one on top of the other.I never saw that done before. I did get about 12 of these single units from GLS a while back I havent got them yet, are these similar to the Humvee units? http://www.govliquidation.com/auction/view?auctionId=7727327

 

[Hawssie]

I think thy look like they need radiator mounted condensers to finish off. Not sure.

 

[WRMorrison]

Nevermind.

-WRM

 

[Over]

Ac finished and riding cool!

Finally got it done! Drove around in 110 and didn't notice it was hot till I jumped out. My son drove while I filmed. I have 3 sons and 2 of them want M923's now! One has a wife that looks at him like he's nuts but knows he'll do it eventually. My son driving doesn't have that chain of command to go thru, it's a matter of getting a place with a side entrance big enough or park at Dad's.I had to put it on medium fan as it started getting cold. I don't see a thermostat to control temp. I guess Red Dot figured in Afghanistan the HMMWV would get to cold with the sometimes 130 air temp. The side vents are perfect at deflecting the air to the passenger and driver as my son demonstrates. I turned it off for a minute to see the difference and it got hot quick. The next project is insulating the cab as on the drivers firewall it leaks heat like a 1500 watt heater is turned on! I am going to route the front vents or at the very least put louvers on them. The condensor fans go off and on and are pretty loud if you're outside. They don't seem to be designed to stay on all the time. Just sitting and not moving in 105 degrees they go on for 10 seconds then off for 40. I just picked up a twin M923A0 to this one with a soft top and will do an install on it. Have to make a different Evaporator mount as there isn't the back wall to mount to. I left enough extra hose on this install so when I relocate the batteries and put in 2 air ride seats I can drop the evap to the floor and make a radio tray or console on top of it. Well here's a few final pics. Oh yeah, I am going to offer AC installs with the M915 kits (I just picked up) locally at a very reasonable price start to finish on the M923A0/A1 trucks. Can do the A2 but cost goes up due to the Kenway higher pricing of brackets.

Here's a video of my son and I heading to the Burger King in cool comfort on a 107 degree day!
https://www.youtube.com/watch?v=LMxLDStrfVg&feature=youtu.be


EVAPORATER IN THE CAB...Messy wiring and hoses need to be cleaned up. I routed the power lead from ignition and the compressor power under the cab to the front and the ign pwr lead thru the firewall back into the cab as I didn't want wires on the floor.

Compressor hookup and hoses (Kenway Eng brackets worked real well.

Fan control/filter boxes in the passenger side under the bed tool box. The condense is mounted on top of it. The hose runs under the cab from the compressor to the condenser, condenser to the dryer, dryer thru the cab wall to the inside evaporator. The only extra wiring off the harness was extending the dryer high pressure and fluid switch wiring plugs from the harness on the drivers side of the evaporator.

Extra hose left over. Also had a pile of fittings, extra O-rings, nuts, bolt etc.

 

[M35A2-AZ]

Way to go!!! I have my system about done just waiting on a new fitting and some new o-rings for the hoses.

 

[Hawssie]

That brings back memories of my time in Queen Creek.

 

[AverageJoe]

New M923A2 owner here, checking in from San Tan Valley / Queen Creek. I need to do this install ASAP. It's a scorcher here today.

 

[Over]

Hi
Been going to lunch in it everyday to check it out. Would freeze us out but I have a leaky firewall with no insulation so it just stays cold not REALLY cold. Time to insulate and sound deaden this weekend. My sister lives in Queen Creek, her husband has a potato farm there.

 

[R Racing]

Finally got it done! Drove around in 110 and didn't notice it was hot till I jumped out. My son drove while I filmed. I have 3 sons and 2 of them want M923's now! One has a wife that looks at him like he's nuts but knows he'll do it eventually. My son driving doesn't have that chain of command to go thru, it's a matter of getting a place with a side entrance big enough or park at Dad's.I had to put it on medium fan as it started getting cold. I don't see a thermostat to control temp. I guess Red Dot figured in Afghanistan the HMMWV would get to cold with the sometimes 130 air temp. The side vents are perfect at deflecting the air to the passenger and driver as my son demonstrates. I turned it off for a minute to see the difference and it got hot quick. The next project is insulating the cab as on the drivers firewall it leaks heat like a 1500 watt heater is turned on! I am going to route the front vents or at the very least put louvers on them. The condensor fans go off and on and are pretty loud if you're outside. They don't seem to be designed to stay on all the time. Just sitting and not moving in 105 degrees they go on for 10 seconds then off for 40. I just picked up a twin M923A0 to this one with a soft top and will do an install on it. Have to make a different Evaporator mount as there isn't the back wall to mount to. I left enough extra hose on this install so when I relocate the batteries and put in 2 air ride seats I can drop the evap to the floor and make a radio tray or console on top of it. Well here's a few final pics. Oh yeah, I am going to offer AC installs with the M915 kits (I just picked up) locally at a very reasonable price start to finish on the M923A0/A1 trucks. Can do the A2 but cost goes up due to the Kenway higher pricing of brackets.

Here's a video of my son and I heading to the Burger King in cool comfort on a 107 degree day!
https://www.youtube.com/watch?v=LMxLDStrfVg&feature=youtu.be

View attachment 501963View attachment 501967View attachment 501966
EVAPORATER IN THE CAB...Messy wiring and hoses need to be cleaned up. I routed the power lead from ignition and the compressor power under the cab to the front and the ign pwr lead thru the firewall back into the cab as I didn't want wires on the floor.
View attachment 501964
Compressor hookup and hoses (Kenway Eng brackets worked real well.
View attachment 501968View attachment 501965View attachment 501970View attachment 501969
Fan control/filter boxes in the passenger side under the bed tool box. The condense is mounted on top of it. The hose runs under the cab from the compressor to the condenser, condenser to the dryer, dryer thru the cab wall to the inside evaporator. The only extra wiring off the harness was extending the dryer high pressure and fluid switch wiring plugs from the harness on the drivers side of the evaporator.
View attachment 501972
Extra hose left over. Also had a pile of fittings, extra O-rings, nuts, bolt etc.

I had my fans cycling alot when we were charging it. We added another 1.75 lbs of r134. And now my fans, stay on as long as the system is on. Maybe that's why mine runs me out of the cabin. I had a company vacuum it down and do the charge.they said it was going out on low pressure til we added the extra r134 . I'm happy with how well they work.

 

[Over]

I had my fans cycling alot when we were charging it. We added another 1.75 lbs of r134. And now my fans, stay on as long as the system is on. Maybe that's why mine runs me out of the cabin. I had a company vacuum it down and do the charge.they said it was going out on low pressure til we added the extra r134 . I'm happy with how well they work.

I'll have to check. I vacced it down to 29 I beleive. I figured I'd drive it a bit and recheck. My gauges are a proffesional set but I noticed as I charged the pressure would go down when the fans went on. Hook up the gauges on Sat and see what happens. Have a great 4th!!

 

[D3M0N]

Subscribing to this thread. This is for sure a project for the future.

 

[Over]

I had my fans cycling alot when we were charging it. We added another 1.75 lbs of r134. And now my fans, stay on as long as the system is on. Maybe that's why mine runs me out of the cabin. I had a company vacuum it down and do the charge.they said it was going out on low pressure til we added the extra r134 . I'm happy with how well they work.

I ran main power from the batts. The switch power is taped into a plug under the dash which may be the heater blower power. That's what red dot recommended in the HMMVW install. My alternator is stock as far as I know. I first charged up with 4 cans (12oz) but the condensor fan kept going off and on. I ended up putting in 6 more cans as my gauge reads 40 psi on low. But I discovered I needed to keep the rpms at 1500 when charging. Now it goes from 35 to 60 psi and pulsates that way slowly. I need to bleed the freon out till I have a steady 40. Will see what happens.

 

[Over]

Makes me want to puke. Their getting rid of in the crate over 500 up armored cabs for demilled (cut up into scrap). Tax dollars at work. Nothing to do with a/c but WTF Over!

 

[R Racing]

It's crazy sad to see it happening. Did 40 psi do the trick ? Or did you leave it on the heavy side?

 

[Over]

OK went out there with the new gauges I picked up from "VRMorrison". Thanks by the way for the great deal on the vac pump and gauges! Anyhow apparently my super duper ORielly gauges weren't working on high side as I never saw anything over 150psi the new set reads up twice as high where the specs say it should be. Anyhow here's the numbers: 95 degrees at 10 pm tonight. 500 rpm L40/H325; 1000 rpm L30/H350; 1500 rpm L26/H380. Now at 2000 rpm which would be cruising in the NHC250 the gauge says L25/H400 now the deal is at 2000 rpm the minute it hits 25/400 it cycles to 45/225 for 4 seconds then returns to 25/380-400 for maybe 10 seconds. What's happening I believe is it gets to 400 on the high side and the controller kicks off the compressor, can't tell if the compressors off as it has an enclosed clutch. It was doing it at 1000-15000 rpm till I slowly released some freon (in the approved manner) till it quite. Now is this natures way (thermostat that has no visible controller) to regulate the temp or am I still a little high on the Freon level? Any help is appreciated. Speaking of spec on the web it says at 95 degrees I should read L50-55 and H275-300.

 

[davo727]

You are way too high, especially at 10pm at night. You need to bleed some out before you blow something in the system. I know your afternoon climate is worse than what we usually get in Houston but anyway If I were you I would shoot for a high side max of 325 and actually would prefer to see 300 max at the hottest time of the afternoon and see how the system cools at 300 high side.

 

[davo727]

I like to charge ac at the hottest time of the day to get the best results. That way you know that you are at a safe pressure on the high side.

 

[Over]

You are way too high, especially at 10pm at night. You need to bleed some out before you blow something in the system. I know your afternoon climate is worse than what we usually get in Houston but anyway If I were you I would shoot for a high side max of 325 and actually would prefer to see 300 max at the hottest time of the afternoon and see how the system cools at 300 high side.

So you recommend 300 when it's 100-115 out? Is that why it's cycling and when it's hotter pressures go up?

The chart I found is as follows:
80degrees L40-50 H175-210;
85 45-55 225-250;
90 45-55 250-270;
95 50-55 275-300;
100 50-55 315-325
and 105 50-55 340-345.

Off topic but those dryer's you have the same ones the M923A0 use?

 

[davo727]

Yes I would try it at 300 and see how it cools. If it is not cooling good enough then maybe it needs to be 325 but I prefer to not stress the system any more than necessary.

 

[davo727]

Were your condenser fans on steady during the time you took those pressure readings?

edit- The fans need to be on if the AC is on. Condenser needs air flow over it, would make it impossible to tell whats going on as far as charging it correctly if the fans were kicking off thus allowing the high side pressure to go through the roof.