Minuit

Pic of actual item for reference:

You got very lucky.

Starting in 93 or 94 they were black. There is a year split at play with the master switch. I believe the master switch assembly changed in 1991. A 91-96 switch panel should be a direct fit. An earlier switch panel can be modified with slight effort. I went through this when I added OEM power windows to my 91 using switch panels from an 88. I can dig up the info once I get home.

It clearly is working out for you. It works out for most people. It is not even close to working out for me, hence my anger towards it. I admit it is not an inherently flawed system, and it works just fine as long as the parts are in good shape and it's bled properly. If my closed cooling system worked, I sure wouldn't be ripping it all out, but on the other hand, I don't really have any patience for it if it gives me trouble. My closed cooling system happens to be attached to a worn out, neglected truck deep in maintenance debt that alternates overheating and overcooling. I found rusty, muddy looking coolant in it, so as far as I'm concerned everything inside is tainted, and the radiator is quite possibly partially plugged. I have no knowledge of the history of the vehicle before I bought it and for all I know the radiator is days away from springing a major leak anyway (it drips a little bit out of one of the end tanks already). The entire cooling system is suspect, and I'm going to replace all of it. It just happens that the new parts will turn it into an open cooling system.

The "foil" will be there, and all of the lights will light up correctly so long as the bulb is there even if they are in different places. If the new cluster is missing a bulb, you can just transfer the bulb holder over from your old cluster. I don't think the MAINT REQD "replace the O2 sensor" light will be there, but nobody cares about that one anyway. When going from my original '91 cluster to the '96 cluster, the only real difference I noticed was that the check engine light was orange instead of red. Some of the warning lights were in different spots, but it all worked out.

Correct.

My next step would be a leakdown test. With compression like that, my thought would be a valve not sealing. Either that, or severe damage to the piston, rings, or cylinder wall. Start with a leakdown test and find out where the compression is going. At the least, my guess is you're probably going to be in it for a head job. If you'll be swapping a V8 soon, may or may not be worth it to you.

Yes, any cluster from 91-96 will fit in your truck. I have a '91 too, but my truck came with idiot lights originally, so I had to buy a HO full cluster to swap in, which came from a '96 - plug and play into my truck, other than replacing the gauge senders. Later on I swapped the 120mph speedo into the '96 cluster. No problems and it was plug and play.

Very interesting. My swap went exactly the same way as described in this writeup, but my US cluster came from a 1996 XJ. That makes me think the '91 cluster is different from 1992-1996. The whole cluster interchanges '91-'96, but the individual parts might be '91 specific. If you can get your hands on a newer cluster than 1991, I suspect you'll be just fine.

The cap that my Dorman bottle came with does not hold pressure. Yeah, yeah, Volvo cap, I know. But I'm not going to sink money into a more complicated, more failure prone system that takes up more of my engine bay, that has more hose connections, more plastic under pressure, and is more difficult to purge air from than the alternative. I also hate the goofy heater control valve setup, and I say that as someone who is generally against deleting the heater control valve. Give me a radiator cap and a nonpressurized overflow tank any day of the week. Just like the '91+ fuel injection system, the '91+ cooling system "just @#$%ing works"

Now all you've got to do is just get it all done before winter! I'm really bad at that part. Do you even have winter over there?

I miss the feeling of adventure that going to the junkyard used to bring. Especially if it was full of intact '80s Jeeps. Now that I've seen basically everything, it takes the REALLY weird stuff to bring the adventure back. Sounds like you captured it perfectly. One of these days I'm going to have to do a big trip where I just go to a bunch of junkyards. Before all of the old Jeeps are in the crusher.

Yep, yep. As long as the gears are of compatible tooth profiles and will actually mesh properly, a 3.31:1 ratio is a 3.31:1 ratio no matter what box the gears came in. So if you had a bunch of gears with the same profile and different tooth counts, you can mix and match all you like. I'm not a rear end guy, but I kind of doubt it's that simple in practice. Someone who has more experience working with differentials would have to confirm, but I'm not so sure that a 3.07 ring gear and a 3.55 pinion gear are compatible even if the tooth counts work out. If it would work, that's my learning lesson for the day I guess.

At least in 1991, you COULD get an Eliminator with a mini console but I have to imagine that almost never actually happened. Bucket seats in "Luggage" fabric were always a requirement to my knowledge, and I think it had to have a grey interior too.

Important: that kit mentions that the compressor is fully charged with oil. That means you won't need to add any. You can drain and refill if it makes you feel better (there should be about 6oz in it) but you don't need to add more as long as the compressor has the correct amount.

Incandescent light bulbs are very effective heaters that just happen to waste some energy as light.

The factory condenser until 1997 was a serpentine design. If the cooling does not satisfy you, you may want to consider an aftermarket parallel-flow condenser. The evaporator issue was one I wrangled with too. I ended up seeking out a NOS evaporator. That thermostat is critical to the operation of the system. In some situations, that thermostat is what controls the compressor cycling. The Renix evaporator is different, so good luck finding one. I'd be tempted to keep the original unless an issue crops up with it. That's not my usual MO when working on A/C, but the evap replacement is a BIG job and not one I'd do if the evaporator wasn't bad. ESPECIALLY if the only available replacement was an inferior part. Get a set of retrofit adapters that have a pushrod for the schrader valve.

The factory charge is 38oz R-12 and 6oz of mineral oil according to the 1990 FSM. R-134a charge weight will be 84% of the original, so 31.92oz of R-134a and 6oz of PAG oil is what you'll want. SD-709 compressors spec PAG 100, but I'm not sure about the 508. Distribute the 6oz of oil however you like. Half in the compressor and half in the condenser, all of it in the compressor (just turn the compressor over about 10 times immediately prior to charging), as long as you get 6 oz of oil into the system. It will be circulated by the refrigerant as soon as the system is turned on for the first time. Apply some PAG oil to all o-rings before installing them. Make sure the o-ring seats before you tighten the fitting. It's hard to describe, but you'll know the feeling once you do it a couple of times. The o-ring should not be extremely difficult to seat, but there should be some resistance. If there is any dirt on any o-ring, it is JUNK and do not attempt to use it. Make sure all o-ring surfaces are clean. If you drop an o-ring on the floor, it is JUNK and do not attempt to use it. Do not reuse o-rings. Work with clean hands and tools at all times. Do not allow any dirt to be introduced into the system. Buy a couple of o-ring sets for the vehicle and have an o-ring assortment kit on hand. Do the service ports have schrader valves in them? The receiver drier should be the VERY last thing you install. Don't even take the plugs off of it until it is mounted in the vehicle and you have the lines ready to connect to it. The system should be sealed as quickly as possible after the plugs are pulled on the drier. It should be replaced any time the system is opened. A vacuum test is not an acceptable method of leak-checking. If your dealership has access to real leak checking equipment such as pressurized dry nitrogen (any proper A/C shop should), use that instead. Failing that, the system should hold a 30inHg vacuum for at least one hour with NO loss of vacuum. If the gauge deflects at all, you have a leak and you will be doing this again, so get it right on the first try. Is your condenser a "parallel flow" design? Those are strongly preferred for R-134a. Using an original-style serpentine condenser with R-134a is likely to result in sub-par performance at idle. That's most of it. I'm sure I'm forgetting something.

Can you measure the height from somewhere on the seat (doesn't matter where, as long as you say where) to the floor so I can compare it to my "correct" MJ buckets? I'm thinking about trying this myself, but I like the seating position as-is and don't want to make it too much higher. There are varying accounts of how much the rocker mechanism raises the seat, and I for one would like to know from someone who has done it. Also, those are some NICE '88 Laredo plaid seats

Yup, the AW4 is one of those "it just @#$%ing works" things. It'll do whatever the TCU (or an aftermarket controller) tells it to. Mine has absolutely no qualms with kicking down to 1st from 3rd and as mentioned before, without the TCU, the default behavior is skipping second gear as there isn't a dedicated position on the factory shifter for 2nd. I have no reason to believe that 2<->4 is any different.

Typically, that gear ratio was used with a 2.5L with 4-speed transmission. The truck being 33 years old now, it's entirely possible that either the transmission or axle(s) have been swapped out. Swapping to an AX5 from an AX4 is a fairly popular and easy swap. Or AMC just had 3.55 geared axles sitting on the shelf that day and decided "screw it, they won't notice" That's why it's good practice to check the axles themselves, either by reading an axle tag, counting the teeth on the ring and pinion, or by spinning the wheels and counting driveshaft revolutions.

Has it off in 3 minutes.

Guess he can set it ablaze and junk it with that attitude.

Yup. Wait for it to learn a fuel map before you go looking for a problem. My '91 MJ and most HO jeeps I've been around do this too! Mine likes to almost stall when going from reverse to drive and the idle is inconsistent for at least a handful of key cycles after the battery is unhooked.