maybe368

I did not, I am still running the replacement shown above. So far so good, it hasn't blown yet. It has been a few years, so I am thinking that It hasn't reached those pressures and I hope that it doesn't. If it does I might try your penn switch idea, if I knew what it is ...Mark Edit: I wonder if the one I got from the ac shop might have been an R134-a switch. I'll call them when I get back to the states...

Jim Lane

This is what a Penn Switch looks like, just an adjustable pressure switch used in Commerical refrigeration, I would use one because I have access to them, check around, there should be high side pressure switch kits available for R-134a conversions,

The trick is you must have good airflow especially at idle speeds or the high side will skyrocket, install an electric fan if possible or maybe a kicker on the throttle to increase the fan speed.

I have seen them stall the engines on 4 cylinder cars and smoke the paint off the compressor.

Jim


JOHNSON CONTROLS Control,Pressure - Single Pressure Controls - 4E040|P70CA-3E - Grainger Industrial Supply

edwinsmith

I read this entire Sticky! Thanks everyone for providing the information. I wanted to buy everything for my A/C renewal except the Evaporator. For the extra $150 bucks and because the condenser looked extra cruddy I went ahead and ordered a new one.

My problem is O'Reilly's doesn't even list the High side hoses assembly (from the compressor to the condenser - from condenser to dryer) and I tried online at Rock Auto and other places as well.

There is a shop in Tulsa that custom makes hoses so tomorrow I'm going to check them out.

Has anyone found a source for these? I don't want to risk making up my own from cleaned parts and new hose.

Edwin

jimbo486

Your best bet will more than likely be the shop you mentioned as nobody makes "drop-in" replacement A/C hoses for our trucks. None that I've come across anyway. I had to have mine custom made when I converted to the Sanden SD709 compressor.

edwinsmith

Thanks Jim. I went ahead and had the shop rebuild mine. They cleaned up the metal parts and crimped on new hoses. Looks good and actually cost less than the NEW low side set that is coming in to O'Reilly's tomorrow. Hopefully they are correct. I also ordered a bottle of the Nylog Sealant and Lubricant memtioned in the sticky. I got the "Blue" because it is supposedly universal for all refrigerant types. I got the pop-off valve for the high side of the new compressor. The only parts that are being reused are the evaporator and the manifold pieces that bolt on to the compressor. All will be thoroughly cleaned as well as I can with the proper cleaning solution and blown out with compressed air and dried. Please wish me luck.

Edwin

edwinsmith

Well after a false start of having to reorder the new condenser because the first one was for intercooled truck, I got it back together yesterday evening.

I put the vacuum pump on it and drew it down to 28" Which is about as accurate as that particular gauge will get. I closed off the valves and let it set overnight. This morning I checked it and it hadn't moved. AN old friend who is in the commercial A/C business told me a good way to check for leaks is to draw it down, close the valves for a few minutes and then open one while listening for a change of tone in the vacuum pump. No change = good.

The guy who was going to put in the R134a for me was busy so I went back to my room where it is cool. Without me knowing he stopped by and charged it. Unfortunately when I got there he had put in 3x12 oz cans and half of a 4th. That is about 44 oz which is what it said on the sticker for R12. That's about 9 oz too much according to what I read elsewhere on this sticky. https://www.dieseltruckresource.com/.../new1/nono.gif

SO now I have to get rid of some refrigerant.

He suggested that I buy a solid fan but I think a better idea is to buy some electric fans to put in front of the condenser.

Has anyone done this? I'll post this also on the main forum.

Thanks everyone.

Edwin

loudhornsrule

I will try to post some pics of my 2 fans later

jimbo486

What kind of pressures can you expect to see on the high side with that much refrigerant? I don't have much knowledge at all in HVAC but I'd be concerned about the rest of the system being able to withstand such pressures if higher than recommended. I believe with R-134a, the charge for our system is around 2.2lbs(?).

edwinsmith

It's been a couple days and I was told the pressure on the high side but I don't remember exactly. Seems like it was north of 250# maybe more. Both A/C guys said that with the sight glass on the dryer showing foam that it had about the right charge. I haven't run it much because I'm waiting to get the electric fans on. Then I'll do a good test. Since the gauges are still there I'll hook them back up and post the pressures I'm getting if I have time.

Jim Lane

Edwin,
If you are using R-134a you cannot go by the sight glass,
However since you are only charging to 80% bubbles in the sight glass could indicate your system was about 20% low or around the correct charge.

Electric fans would only be working if you were stationary or low cruising speeds anything much over 20 mph would be pushing the fans anyway.

The correct way to service the AC would be with a BIG electric fan in front of the condenser to simulate crusing speeds.

If I am not sure on my charge I simply recover it and start over.
But of course I have my own recovery machine.

Jim

edwinsmith

I know the sight glass is nearly meaningless except to see if anything is moving. From what I can find the ratio of R134a to R12 is 85-90% R134a. There is a big sticker on my radiator shroud that says the system should be charged with 44 oz of R12. At 85% R134a it should have 37.4 oz. Unfortunately the A/C guy who was helping me charged it when I wasn't there and he put in about 3.5 x 12 oz cans of R134a or about 42 oz. which is where I am right now. (In Oklahoma everything is about so much.)

I'm still waiting for my fans to come in so I'll be reporting back on pressures and such after I have them working. I can't drive the truck around because the bed is off and no lights or tag.

I'm debating if I should have a few oz of R134a removed or just leave it alone and see how it works.

Edwin

samiam4

If you want a correct expansion valve is if you look up an earlier gen 1. Tell them it's an 1985. Everyone's database will point you to 94+ to 2002 experience valve.

M

edwinsmith

I have an 89 model and my expansion valve doesn't have the low pressure switch on it. It has a much bigger switch on the low side hose coming out of the top side of the valve. They must have changed the configuration of the system in 1990.

The old valve I took out has a number stamped on it which is "040138-202 1011B". The Murray part number is "38849" from O'Reilly which is what I installed.

Does anybody know if the 1989 had a similar part number screw up?

Edwin

samiam4

Edwin,

I'm looking in the distributor catalog and here's what I see. If I pick 89-93' expansion valve it goes to 31-30971 which in it's parts description says "94-2001". If you check 1985, then it comes back with Part number 31-30909 which is 4Seasons "38838" which is "1978 to 1993". Every mcautoparts catalog does the same thing...

I would look getting a serpentine evaporator coil (27-27992) and a parallel flow condenser. The custom condenser will mean moving away from the Chrysler seals and making up a custom line. Both of these will perform better with R134a than the original R12 coils.

Jim Lane

I bought my condenser from OReillys by application for a 1991 and what they shipped was a parallel flow, I was able to use all of the factory mounting and connections,
However I did make all of my custom lines by welding on new fittings and using Aeroquip hose.

Jim