fhorta

Hi all. Hoping I can get some suggestions, ideas, advice, comments. Thanks in advance.
I have just replaced a bad condenser on jeep and in process now of pulling vacuum before refilling condenser with oil and putting freon in. After everything was putt together, i pumped compressed air in and the pressure held.

When pulling vacuum I have gauges reading 30 on blue side but begin to lose it though. Thinking it might be the retrofit fittings from R12 to R134A. Right after pulling vacuum, I pull the adapter hose from port, release pressure in hose, then reattach and I get 30 again, but if I leave hose in I begin losing vacuum. I vacuumed and left it at 30 vacuum overnight isolated no hoses attached. This morning had lost all vacuum, so can't be the adapter fittings on manifold gauge hose. Now I'm not sure where leaking from. I done a compressed air test , sprayed hoses, fittings, attachments with soapy water but found no bubbles. Also, I don't lose compressed air pressure. Could leak be so small through the port fittings that it wont blow bubbles? any ideas how to go about finding leak and eliminating possible causes? First time doing AC work.

Thanks again

agreen

Compressor shaft seal. It's notorious for that. Won't hold vacuum ever, but put a pressure on and it stays. It acts like a check valve. I'm not saying I've seen it particularly on XJs, but it's common on pretty much any car.

fhorta

Thank you. So if leaking through there, how could I isolate that part to verify? Thanks again

agreen

Since you said you had to convert from R12, I'm assuming the compressor has service valves. Shut those and you can test the compressor. Here's a diagram:

fhorta

Yes i messed with those at different varying positions but wasnt quite sure if i was closing or opening, or in middle. So to test compressor, do i "back seat", front seat, or middle seat them ? thanks!

Saudade

Back seated is the normal position for operation. Once finished, back out (counterclockwise) until they seat.

Front seated is for servicing the compressor without losing all your refrigerant. You only lose what's in the compressor.

If you count the number of turns from back seat to front seat, halfway is the service/test position. Use this to evacuate and/or charge the system.

The r134 connectors should seal when you disconnect them assuming they have schrader valve in them . I would still backseat the service valves.

fhorta

Ok. A dumb question b efore I do this; When vacuum is pulled, are both, high and low sides being vacuumed? Or does it depend on if you open the manifold gauges? So if i only open blue hose manifold gauge, the red side is still vacuuming? Reason I ask is if i wanted to isolate either side if it was possible to see which side may be leaking. Or is that where the service valves come in? Close one completely and service the other; one by one?

agreen

You'll want to completely isolate the compressor by shutting both and draw a vacuum from either side or both. I normally vacuum from both sides. If it loses vacuum with the valves shut, you'll know it's the compressor. You could even draw a vacuum on the whole system and isolate the compressor, check for a leak on the compressor, then restore the system to the compressor to see if it was still holding vacuum.

fhorta

Close service valves off, pull vacuum from both sides, reach 26 to 31, close manifold gauges. Is that pretty much the sequence? I think I'm missing something. If i close service valves and then try to pull vacuum, it won't pull cause service valves are seated shut, righ ? So my sequence gotta be wrong. I received new retro fittings in mail today. I'm also going to install. Maybe the leak is from a shrader valve. Thanks so much.

agreen

I think the part you're missing is that the service valves are to allow you to service the compressor without discharging the whole system. So with the valves shut, all you would be drawing vacuum on is JUST the compressor.

Saudade

What agreen said.

Normally, the service valves would be in the mid position to evacuate with both manifold valves open. If you want to test/evacuate only the compressor, front seat the service valves. It should build vacuum quickly due to the smaller volume. Then close the manifold valves (leave service ports front seated) and wait to see if the vacuum drops.

When you're ready to charge the system, close both manifold valves first. (this traps the vacuum). Then set the service ports to the mid/test position. If you need to evacuate some more, simply turn on the pump and open both manifold valves. Reach full vacuum and close the manifold valves. Wait some more. If it holds vacuum, you're ready to charge.

When ready to charge, make sure both manifold valves are closed and then the service ports are in the mid/test position. Connect your refrigerant source to the charging (yellow) hose and open the can. Now very carefully, briefly, crack open the yellow hose fitting at the manifold gauge. This will purge the hose of any air. Make sure all fittings are now tight. Start your Jeep and turn to any AC setting.

Now open ONLY the low pressure manifold valve. The vacuum in the system will draw out the refrigerant. The can will get cold so it's nice to keep a bucket/pitcher of hot tap water to dip the can into to help keep the refrigerant flowing. Once enough refrigerant enters the system, the clutch should engage and compressor kick in. Once the can is empty, CLOSE THE LOW SIDE MANIFOLD VALVE (yes, I'm shouting). If you don't you'll either draw air into the system and have to start over, or lose refrigerant. Then connect your next can and repeat. My fitting has a shutoff valve at the can end so I close the valve before disconnecting the can to prevent air from entering or refrigerant escaping. Now rinse/repeat until the system is fully charged, If the pressures look right and the ac vent outlet temp is good (varies with outside temp), back seat the service valves. This closes the AC system. Close the low side manifold valve (high side should still be closed), and disconnect the QD fittings from the ports. This will trap the refrigerant in the lines so they be for next time.

My '88 still uses R-12 so I can't say for sure how much R-134A it will take to fill. Typically it's 75-80% of the R12 charge by weight. There are plenty of threads already that should include the pressure charts for low and high side as well as the outlet temp. All these vary based on outside air temp.

fhorta

Thanks for replies guys. So I did the following:both service valves all the way clockwise-towards back of car-loses vacuum.



Top service valve all the way counter clock wise-towards front of car, and bottom all the way clock wise-towards back of car-loses vacuum.



Both all the way counter-towards front of car-holds vacuum.



Top in middle, bottom all the way counter-holds vacuum.



Top all the way counter, bottom all the way counter. Leave top alone, and as soon as bottom is turned from full counter to clock wise, loses all vacuum

This sound right? Did I isolate compressor by turning both service valves all the way counter clock wise? If so, it holds vacuum at 31. Been setting at 31 for last 10 minutes or so.

agreen

When you had them all the way clockwise (both) you had the compressor isolated from the rest of the system. Since it didn't hold vacuum, it means it's a bad compressor seal. When you backseated the valves (both counter-clockwise) you essentially tested the adapter fittings and your hoses. So that would make sense that it held vacuum. One in/one out means nothing really.

TL;DR
Replace the compressor

fhorta

Ughh. Ok, makes sense. I am trying to order the ac compressor shaft seal. The only thing on compressor to identify what compressor it is 709T on top of it. Besides that on the R12 refrigerant sticker, sticker it says OK SAE J639. Any ideas what compressor i have so i can order right seal?

fhorta

Ok. I think i got the compressor specs. Barely able to read "sanden" and seems the 709T is the identifier. Now as i try to get to the seal, I'm not sure if clutch is supposed to slide off the splines by hand or if special tool required? I looked it up and some say slides off., others use a puller thing. THANKS.