Small leak

[Dave in Texas]

Rebuilt my trucks R 12 system in 2012. Had ACKits rebuild my hoses and replaced everything new ('cept condenser & evaporator) did use a rebuilt compressor though (Murray I think). All was fine until a few months ago when the inside temps would not get below 55°. Today I had the R 12 removed at local AC shop. When I got home and everything was cooler, I replaced the rubber schrader valves with the plastic type. Pulled a vacuum to 28in plus a tad for 45min. Gage showed 23in about 15min later and 18in after another 15min. Checked the hose connections and the valve tightness. Vac'd again. Same result.
Main suspicion is the OE condenser. I replaced the OE evaporator in '96 due to a pin-hole leak. Any point in dye testing either of those? Cond is '81 vintage and evap is '96 vintage. No visible oil on any of the connections (Nylog on all).....
What is the right path to follow?
Thanks








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[Cusser]

Well - and you know this already - leak testing a condenser is way easier than such for an evaporator, just because of access. Yes, I think UV dye can help pinpoint a condenser leak or maybe an evaporator leak (test the condensate drain) if you have UV light and goggles; maybe an electronic sniffer in the vents or condensate drain can help with the evaporator without opening the box.

It's also possible that you have some leakage of the compressor seal over the last 4 years too.

What are your thoughts about paying that AC shop to pinpoint the leak, as they have all the tools, and experience? How many ounces did the shop say the system was low?

WHATEVER YOU DO, DO NOT ADD ANY SEALER TO THE SYSTEM, YOU'LL RUIN IT !!!!
WHATEVER YOU DO, DO NOT ADD ANY SEALER TO THE SYSTEM, YOU'LL RUIN IT !!!!
WHATEVER YOU DO, DO NOT ADD ANY SEALER TO THE SYSTEM, YOU'LL RUIN IT !!!!
WHATEVER YOU DO, DO NOT ADD ANY SEALER TO THE SYSTEM, YOU'LL RUIN IT !!!!

[mk378]

It doesn't hurt to keep dye in the system all the time to help find any leaks that might occur.

[Dave in Texas]

Thanks. I know better than to use sealer.

I'm unsure of the Snap-On gauge set I use. It may be the issue and to verify the set I used the following procedure. Attached the center service line (Yellow) to my vacuum pump. Closed the valves on the manifold set. Pump On. Nothing happened. Attached the Low pressure line (Blue) to both ports on the low pressure side. Pump On. Vac'd to about 24". Shut Off pump. Immediately lost vacuum(woosh). Hose problem? Correct procedure?
The set is over 20yrs old, so... Last time I used it was in 2012 and all was fine, but it was still old then.
Trouble with hiring the shop is that I'd have to leave the truck there. I'm isolated here and there are no friends available for rides. Too old, too hot and shop too far away to walk.
The system is empty so......kinda up the creek with this problem.
Thanks

[Cusser]

If I was in that situation (don't know how many miles away shop is), I'd throw my bicycle in the back of the F-100, ride that home. And later ride that back and pick up the F-100. And I'm 63.

[wptski]

Thanks. I know better than to use sealer.

I'm unsure of the Snap-On gauge set I use. It may be the issue and to verify the set I used the following procedure. Attached the center service line (Yellow) to my vacuum pump. Closed the valves on the manifold set. Pump On. Nothing happened. Attached the Low pressure line (Blue) to both ports on the low pressure side. Pump On. Vac'd to about 24". Shut Off pump. Immediately lost vacuum(woosh). Hose problem? Correct procedure?
The set is over 20yrs old, so... Last time I used it was in 2012 and all was fine, but it was still old then.
Trouble with hiring the shop is that I'd have to leave the truck there. I'm isolated here and there are no friends available for rides. Too old, too hot and shop too far away to walk.
The system is empty so......kinda up the creek with this problem.
Thanks

Were you isolating the system when you lost vacuum? A pump won't hold a vacuum of its own.

[Dave in Texas]

No, not the system. As I said: I am trying to verify the old gauge set with the procedure I thought was the right one to verify the set was not leaking.

[wptski]

No, not the system. As I said: I am trying to verify the old gauge set with the procedure I thought was the right one to verify the set was not leaking.

I followed what your testing but not how you were connected and to what. If your gauge set has dummy fittings for hose storage, you could connect the blue/red on them but you need a valve to isolate the yellow hose, that's what I meant by "system". Some pumps have a blank off valve for that but they are known to leak. In that case a fairly good ball valve is needed. My JB Eliminator doesn't have a blank off valve so I use these and they hold a vacuum: http://www.centurytool.net/Hose_End_Bal ... cpsbv3.htm

[Dave in Texas]

OK, I understand. I believe I will retire the 30yr old SnapOn set and purchase a new R12 manifold set. Less hassle. Thanks for the response.

Just to have on-hand and because parts are getting hard to find, I have a condenser, evaporator, accumulator and new compressor on the way. None are inexpensive but none will get any less expensive as time goes by.