Hello and can you help me?

[KingArthur16]

So awhile back I bought this mil spec 1988 G30 that came installed with this non-functional 12v air conditioner pre-installed. It's essentially a CUCV except with a GM box van body. It was used as a personnel carrier at an Air Force base in Arizona.







It's a product produced by a company called Frigette, which of course is no longer in existence.

However, parts for this cooler seem to be readily availiable via military surplus and not terribly expensive. So what I'm asking is do you think it's worth trying to salvage this thing? Where would I even begin to look for someone who would be able to make an assesment on this thing if it's salvageable or not? I don't even know if it runs on 134-A.

The top side looks to be a very simple unit with nothing more than a radiator and two fans. The motors of the fans could be replaced fairly cheaply so the outside split I'm not worried about- that can be fixed.

The inside split I know nothing about. There seem to be some things missing to my mind. I don't see a pump or drier or any of the other fixings that should go along with an AC. Unless it's all tucked away inside the blower housing.

Do you think this project is too ambitious? It would be cool to have a split AC in the van... but if it's going to take the majority of my life force to get it working I can move on to something else...

 

[Keith_J]

Its most likely R12 and the compressor is on the engine. I would replace the compressor with a modern R134a unit, flush the old mineral oil from the evaporator and TXV, replace the hoses with modern barrier units, evacuate and charge.

If the compressor is worth salvage (turns freely and makes pressure), there are alternative refrigerants but these are hydrocarbon based so no flush. But they are flammable. Risk is minimal as compressor and most high pressure plumbing is outside the cab. But I would recommend replacing everything on the high pressure side including the thermal expansion valve.

Follow the hoses and you should find the compressor attached to the front of the engine.

 

[KingArthur16]

Its most likely R12 and the compressor is on the engine. I would replace the compressor with a modern R134a unit, flush the old mineral oil from the evaporator and TXV, replace the hoses with modern barrier units, evacuate and charge.

If the compressor is worth salvage (turns freely and makes pressure), there are alternative refrigerants but these are hydrocarbon based so no flush. But they are flammable. Risk is minimal as compressor and most high pressure plumbing is outside the cab. But I would recommend replacing everything on the high pressure side including the thermal expansion valve.

Follow the hoses and you should find the compressor attached to the front of the engine.

Thanks for the quick reply.

Correct you are. The compressor is attached to the engine and has been bypassed with an idler. Not sure if it turns freely; looks like an electric-clutch style compressor. I suppose I could just grab it with a pipe wrench and teach it a lesson to verify if it still turns and has compression. Barring better advice of course.

I like the idea of replacing what needs to be replaced with modern components. Is this something that I could take on with little knowledge of vehicle HVAC? Is it possible to convert it to run on an electric compressor? I'm confused as to why it has two condensers, one in the front by the radiator and the one in the white housing on top of the box. Seems like one could convert it to just use the one on top with an electric compressor perhaps?

 

[SCSG-G4]

There are two 'condensers' in almost every A/C unit ever made. One is to cool the compressed gas that has been turned into a liquid by the compressor (the one in the engine compartment) and the other coil is where the expansion valve unit is. Here the liquid refrigerant is allowed to expand rapidly and thus cool. Air is then blown over these coils to cool the air in the passenger compartment and out through vents. The refrigerant gas then goes back to the compressor to repeat the cycle as long as the compressor is running.

 

[Keith_J]

No way to run a compressor off of 12 volts. Unless you are very handy, any electric automotive air conditioner is going to be very expensive. Yes, they are out there but they run special lubricants (hermetic compressor with motor in refrigerant) and typically draw 40+ amps of 24+ volts.

I bet this system was drawn down as it had R12 and the Air Force was under directive to recover all thanks to the Montreal Protocol (un legislation banning R12).

If it has two condensers, that is because there is a lot of heat to reject. Air conditioners move heat using energy. This means that heat must be rejected along with the energy required to move it. Compressors have two hoses, one larger than the other. The larger hose/tube is suction, the smaller is high pressure gas. Follow the small line to see if it first goes to the front mounted condenser. Then follow the other condenser line to see if it goes to the top mounted condenser..by moving the refrigerant in the gas phase to the second top mounted condenser, less refrigerant is needed.

From the top mounted condenser, it should enter a receiver dryer and finally the thermal expansion valve (saw it on the picture of the evaporator). This device meters liquid refrigerant to prevent evaporator ice.

I would keep the system as designed, using a SNAP approved hydrocarbon refrigerant after hose replacement. These refrigerants have higher performance than original R12. The main reason for Delco's development of halocarbon refrigerants was flammability of hydrocarbon. Engineering development over the past 90 years has made leaks rare except in accidents, then it leaks on the outside.

Test the compressor by applying 12 volts to the coil to engage the clutch. Is it round? Or does it look like an air compressor? Round would be Frigidaire, another Delco development. But if it is bum, a Sanden SD7H15 will be even better. You must replace the charge fittings with what ever refrigerant used and properly label these fittings with the refrigerant used.

 

[KingArthur16]

I think at this point I'm going to just scrap the idea of salvaging this cooler altogether. It would be fun to tackle but I've got other concerns on the vehicle I need to address first. I'll probably just slice the hoses and pull it off. Oh well, onward and upward.

I'd like to put some taller gears in the diff because right now the thing is roaring at about 55, and I'd like to bring it down more into the LL4's peak torque curve which looks pretty flat from 1900-2400rpm. I pulled off the cover yesterday and its got 4.10's at the moment. According to online calculators putting 3.42's in will bring it into a better range for cruising speeds. It shifts into 2nd maybe at ~9mph so I think the change is needed.

I called the junkyard and they say they have two 14-bolt GM rears. They don't know the ratios. I'd have to go by the RPO (if they're there) to see if they have anything close to what I need. I'm assuming that just putting a different rear on the truck is going to be the easier route than trying to swap the gears myself. I have access to a press so I can replace the bearings and bushings and whatever else, but a rear from the junkyard is only 100 bucks. That's a few hundred less than buying the parts I need to do the swap and will probably save me many hours of stress.

Do any of you know if the full-float 14-bolt will meet up with the mounting points for the shackles and strut mounts? It would be nice to put a full-float on there if they have one available by some lucky chance.

 

[Keith_J]

Careful on gear choice. Even though you have fat torque curve at low RPM, the 4.10 really helps get those 8000 pounds of vehicle weight off the line. This is why I am going with an OD in my M1031 (right now sitting portly at 8300 pounds). I will be using a modified 4L80 with a lower first gear and some other mods to turn it into a 6 speed. The ratios are 2.97, 2.23, 1.57, 1.18, 1.00, 0.75. Compared to the stock 2.48, 1.48, 1 and 0.75 Keeping the engine in the torque peak also can keep the engine in the lowest brake specific fuel consumption. I say can because lowest BSFC happens at greater throttle position, you still have to consider exhaust gas temperature and making more NOx means less efficiency.

The engine isn't going to grenade by running it at 3000 RPM for hours. What kills older engines is age hardened harmonic dampers at lower RPM. Idle speed is hardest on the crankshaft.

 

[KingArthur16]

Forgive me for the brief words in this post I'm posting from my phone. A couple things:

- I've decided rather than trying to chance the diff gears I'm going to swap in a 4l80e. I need to remove the transmission anyway to do the rear main so that's sort of nice I guess. The 4l80e only needs throttle position and engine speed to run its PCM. This guy made it work without having to buy one of the overpriced kits that make the 4l80e standalone. However I do have to figure out how to add a tps to the 6.2.

- This forum probably has more experience with the 6.2 than any other since it's used in the CUCV. Something has been bugging me about this engine for awhile now and everyone, including the mechanic that inspected it, seems to think it's normal. To me it sounds like the injection pump is eating itself and causing misfire.

Below I posted a video of the engine running, and it's nearly impossible to hear it on the video, but maybe one of you knows what I'm talking about. Whenever the engine gets warmed up, it seems to start to misfire. The 'ratcheting' sound produced by the IP will get louder and softer, loud and soft, and sort of jitter between those two volumes. Maybe you can see in the tailpipe the rattle that seems to follow the loud ratcheting sound that comes from the IP. You can hear at the tailpipe how it's sort of running rough. What do you think it is?

https://youtu.be/ZW3DUkYGZUk

- I've read elsewhere that the harmonic balancer can be the reason the rear main seals go on these engines. Looks like it's pretty wobbly to me: guess its time to replace it.

Thanks. Here's some pictures of the work I've been doing to it today. Going to patch all the holes and paint all the rust next week.