Reviving a 44yo ac system tips ???

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PhillH

PhillH

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My Scamp is a 1971 with factory, not dealer installed AC, I rebuilt the compressor with new gaskets and PAG100 oil. I have a new dryer not installed yet. When I took the compressor out it had a little bit off pressure in it still. I have a new vacuum switch for the dash controls. What kind of oring seals are the best to use and where to get them? Also I plan on replacing the expansion valve as the little copper tube broke as I was moving it. The fan works. Any thoughts on if I'm missing something or procedures I need to follow? Also the lines I plan on having the rubber redone at the hydraulic shop but what are the little muffler things? Do they have anything in them that goes bad or are they just for sound suppression? Sorry so long, any input is appreciated, thanks.
 
Hi,

Sounds like you have many of the needed issues covered. Did you replace the shaft seal in the compressor and the seal housing O ring? You should have 8 to 10 oz of oil in the compressor.

The o rings should be HNBR types and are frequently green in color for use with R-134A. The o rings should be coated with a drop of 525 A/C mineral oil are you assemble them. You can also use something called Nylog, blue tube for R-134A.

The muffler are sound impulse suppressors. You should flush out the evaporator and condenser with some A/C flush solvent and blow out with plenty of compressed air. You want to get any old oil out of there as the old oil doesn't get along well with PAG. Your new receiver/dryer should be the last thing you install in the system as you close it up. Then connect your gauge set and pull a vacuum down to -29 inches and see if it will hold that vacuum. I usually let it sit overnight. Then charge your R-134A into that vacuum. Start with about 75% of the R-12 charge.
 
Yes I completely dismantled the compressor and clean and put in a whole new gasket set including the shaft seal, torqued all the bolts. I'll use your advice as a guide so thanks you for that. The dryer will stay sealed till it goes on. Once I get it all together I'll take it to my mechanic for vac and fill, I'll make sure he follows your directions. I did find the vac hoses coming through the firewall are dryrotted so I'll replace those all the way to the switch. Is there a kit with all the proper size orings?
 
As far as I know there are no specific O ring kits available for these old systems. There are master O ring kits but they would be a bit pricey for what you want. You only need a few rings. I would collect all the O rings in the system and take them down to the local parts place and match them up from their master kits. Make sure they are A/C system rings, R-134A compatible and not just general purpose O rings.
 
I bought an assortment from oreillys auto parts that had every o ring I needed for my dart. Still have several left over. It was around $10 or so.
 
I check on that, is there a color that I should be looking for, or just nitrile?
 
All of the A/C orings that I have used are green. However I'm sure you could get them in black if you wanted.
 
Use Ester oil. It is compatible with mineral oil, so if you don't get all the old oil out is no big deal.
 
To late for ester oil, the copressor is already filled with PAG100 and on the car. I don't mind giving it a good flush.
 
Can someone explain to me how the copper probe that goes into ac line from the expansion valve is supposed to seal? My stock system just has a little rubber cone that slides down over the hole. I can't see this being a very good seal?
 
That little rubber cone is just a dust seal to keep dirt out. The copper probe is a temperature sensor that fits into a well in the refrigeration line. There is no contact with liquid or gas refrigerant. Just slide the copper probe down into the well in the line.
 
LOL, Thanks, I knew there had to be something to it. Feel much better about it now.
 
Small update. I installed the vacuum switch buttons and replaced the vacuum lines reservoir and heater valve. Everything works perfect! Lucky me.
 
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