1988 4964f A/C problems

Trinary switch, depending if it’s female or male. (Female) OEM# RD5-4625-0. Truck Air/ MEI#11-2627. ( Male) OEM# RD5-4585-0. Or # 02-2750417. Truck Air/MEI# 11-2625

 

Expansion valve, here’s what the book says. I notice yours says 134A. Can’t find that # though.

 

Blow the freon and check the compressor oil,if it s grey or black you know the compressor is bad

 

Here’s the ones showing in the book. Last 3 on list aren’t shown at all.

 

Apparently someone has upgraded the valve. No telling. Here’s an example of an r12 and a 143a ones 2 ton, others a 2.5 ton. Tonnage rating, along with type of thread/ fittings seems to be the key to finding the correct valve in your case. They also have plugs available if needed, to make a 4 hole work as a 3 hole. You really should just change out that compressor, along with new ported 134A lines, if you don’t already have them. New compressor doesn’t have ports, like the R12 compressor does. I can look up correct compressor based on plug, pulleys, and hose fittings. New hoses will need to fit new compressor. Depending on what combinations are available, there’s different options sometimes. It would be best to get a common compressor, that’s readily available, due to cost differences. Oddball compressors are a lot more $$ and hard to get. Nows the time to pick a compressor and get proper lines/fittings for it, and expansion valve, and condenser.

 

You can call MEI, they’re very helpful. I can’t find the #. Maybe @Dino soar has it. He just built his own system from scratch.

 

Ride and repair has a lot of good information about these compressors and the parts.

Honestly my own personal opinion is if the truck is that old and you have no history on if any of those parts were ever replaced I would replace the compressor the condenser the dryer and the expansion valve and possibly even the evaporator. I would make sure you flush the hoses really well and flush the evaporator and see how dirty it is and how clean you can get it to come out of there. Autozone or Advance Auto Parts has an AC flush that will work really well, just make sure you blow it clean with compressed air.

If you replace the compressor and the whole system you know that you have the right amount of oil and the right amount of refrigerant and your system will work at Peak efficiency.

My guess would be there's moisture in the system and that is why your expansion valve is freezing up. Did you pull a vacuum on it? Also your dryer is really supposed to be replaced every other year or every few years anyway, or whenever you open the system up. If the desiccant inside is not able to filter properly if there is any moisture it will make your expansion valve freeze up.

If your switches are working I wouldn't worry about them right now because they're simple to change. But you do have to make sure you get the dryer that has the right size threads for them.

If you are planning on replacing the compressor let me know what engine you have. I have to take a look at the old compressor but that may be the same number that my old compressor was.

 

I know everyone has said you can just flush the lines, and thats true, you can, but do yourself a huge favor and just replace them, evap, flush it, thats probably no problem, but if the condenser has more than a year on it, just replace that too

The advantage to doing it this way will be that you wont just buy the oem ac lines or be bound to that, you pull your old lines and mark each one with the changes you want made to them and have a shop make new ones, use as little metal line as you can. You will still obviously need some near the txv valve and compressor and basically all the hose ends, but doing it this way should save you koney long term and you can route your hoses intelligently instead of the way theyve been. While youre at it, find a standard condenser you know and like, and just figure out what changes will need to be made to make that work both mounting and hose wise.