I think AC is the bugaboo of Delicas. If the AC is not functioning they are undriveable in hot weather.
So you have had your compressor rebuilt This is a good place to start.
These vehicles are OLD, with front and rear AC there are a lot of seals. There is an O ring in EVERY connection. The OEM ones are black and are 25 YEARS OLD. In an AC system you are trying to contain a high pressure GAS. It will exploit the smallest leak to escape. Your compressor has failed this is a good sign of a leak. In an AC system the compressor and expansion valves are lubricated by oil traveling through the system with the refrigerant gas. When a leak develops the gas leaks out, rate depends on size of leak, we are talking nearly microscopic here. As the quantity of refrigerant leaks out it's ability to circulate oil is reduced. Lack of oil for lubrication of compressor is generally cause of compressor failure. Not the only possible cause but most likely.
When you replace compressor you are going to have to recharge the system. If you have not fixed the leak(s) repeat failure is very likely. Therefore while you are working on it and the system is empty I recommend replacing all of the accessible O rings. We have the same van. Mine is green too. When I bought mine compressor was growly. I added some refrigerant, compressor was unable to develop any pressure. A couple days later laying under van I saw oil drip hanging from an AC line fitting near transmission. Not a good sign, must be a leak. I bought compressor from Ali Baba. $100 for part $114 to fly to US from China. Only took six days after my payment cleared. Before installing my compressor I replaced all of the accessible O rings. This a big project. My biggest issue was getting vinyl bumper skin off. The four bolts from the wheel wells were rusted to their captive nuts. I bought a Dremel and cut the heads off of the bolts after I spun the first one and could see it was tearing the vinyl. I studied the manual and followed the pipes on vehicle. Eventually nearly all O rings were changed. The only ones external of the AC cases I did not touch were the small lines to the front and rear isolation solenoids because fittings were corroded and I figured I would be breaking things, corrosion can plug leaks too! With the O rings changed and compressor and new receiver dryer installed I wanted to verify system is gas tight at high pressure. I charged it to 250 psi with nitrogen and let it sit 24 hours. It leaked, a 50 lb. drop in 24 hours. To big to ignore. I studied some more, I had missed the O rings in connections under battery tray. Replaced those O rings, recharged with nitrogen again. This time minor pressure drop overnight, attributable to temperature differential over night. Now I was confident I could charge the system and it would not leak. I had another problem I have not addressed yet but it has been approximately 2 years now and system is still full, no bubbles in sight glass on top of dryer.
You asked about flushing condenser. Lets discuss that. Starting with the compressor. Gas flows from compressor at high pressure, up to 250psi on a hot day. from there to receiver dryer. This is a small aluminum bottle mounted on radiator core support between radiator and left headlight. There is desiccant and filter in this bottle. If you are LUCKY all of the chips from your compressors destruction wound up here. There are two condensers with front and rear air, one in front and one underneath body between transmission and sliding door. To see if there are chips in condenser I blow compressed air backwards through condenser, from outlet to inlet. I tied a white handkerchief to the inlet fitting to trap what comes out of condenser. If there are no chips just dirty oil be happy. If there are chips there are AC solvents that can be used to clean out condenser. I was lucky no chips in mine. Before installing compressor blow the discharge line out, again reverse flow, dryer to compressor. Again you can use handkerchief toe make sure it is flowing clean. There several places you do not want debris in the system. 1 compressor, 2 expansion valves ( very small orifices here, easily plugged) and the isolator solenoids. So far I have been blessed, no problems with refrigerant system after two years. I really believe that my time spent replacing O rings was well worth it. If you do not have a service manual GET ONE. Become familiar with it, Print the pages for what you are working on. This by no means exhausts the places you can have issues but it is a good start. The service manual has a system performance test that my van passed. My pressures and temperatures were very nearly exact to what the manual called for.
A word about O rings. The OEM O rings are black, likely neoprene. After 25 years they are old, can be dried up and shriveled. Corrosion can have eaten at them and their mating surfaces in the pipes. There is a new material that is green better suited for R134a. I just looked up material, it is hydrogenated nitrile. O Reilly Auto Parts sells a large assortment of green O rings for about $20 that fits almost all of the fittings. I remember there were a couple sizes I needed not in assortment. I recommend a NAPA store for those. I polished any white corrosion found on aluminum connections with a green scotchbrite pad.
A word about dryers: I sourced my first one from Coombs Country Auto, a little pricey. Since then I have spent some time in wrecking yards her in Ca stripping parts from Monteros and learning what is similar to Delicas. I believe that a 2004 Montero uses the same dryer as the 95 Delica. Match yours up at a Napa store and see if I am correct or not. Much cheaper.
Good Luck. Kevin
