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Checking for refrigerant leaks in A/C...

Started by 62 CDV, April 09, 2019, 02:54:36 AM

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62 CDV

The vast majority of Cadillacs with A/C in this Club have air conditioning systems that originally operated with R12 refrigerant. My '62 CDV is no different. Since all of my A/C hardware in the car is designed for R12, what refrigerant would I now use in order to find a leak or leaks after evacuating my A/C system?

Thanks in advance for the due diligence.

Dan LeBlanc

#1
Pressurize the system with nitrogen and let it sit for a couple of days.  Leaks that may not show up under vacuum may show up under pressure.  Then evacuate the system and charge with refrigerant.

If you have Ester or Mineral Oil in the system, you can charge with R12.  If it's PAG oil, you're charging with R134A.

If you don't know what's in the system for oil, it's best to start with a clean slate after thoroughly flushing, adding the oil per the factory service manual, then charging.  As Greg Surfas does, charge the first couple of pounds as a liquid through the high side port, then complete the charge to the required capacity as a gas with the car running through the low side port.
Dan LeBlanc
1977 Lincoln Continental Town Car

TJ Hopland

Another important question that doesn't seem to get asked or answered often when asking about AC service is when was the last time the system worked?   Worked last summer takes a lot different plan of attack than hasn't worked since I owned the car. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Scot Minesinger

Going from r12 to r134 is not too bad, just need to flush out the system.  However, going from r134 to r12 requires a more thorough clean and flush.  Either way be real sure what refrigerant was in there, hopefully 12.  Then proceed accordingly.  Given the choice, especially if r12 was in there, and since r134 is now a greenhouse gas might as well go to r12 (Factory), it does work better.  Just research the clean out and flush procedure for 134 to 12 if 134 was in there.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

62 CDV

I remember Greg Surfas years ago recommending R414B as a drop-in replacement for R12, but it had to be put into the system as a liquid and therefore required installation by a professional. Is this still a viable plan of action for these cars?

Thanks in advance for the due diligence.

walt chomosh #23510

E,
  I ran 134b in my 55CDV, then went to 414b (called Hot Shot...go to their web site for info) for a number of years....that is, until I bought a 50# container of R12. I was never satisfied with 134 so I went to 414b (I still have it in a couple of Fox Mustangs and a 64Chevelle) and was reasonably pleased.  The R12 has been working well.....walt...tulsa,ok

"Cadillac Kid" Greg Surfas 15364

In regards to your question of what to use for leak checking AND you have Nitrogen (with a regulator to limit the pressure to about 250#) available, that with either an electronic leak detector or s "soap bubble" type leak detector fluid is ideal.  I typically use R-22 in my R-12 or R-414b systems.  You did not say whether there was any refrigerant in your system before you "evacuated" it, or how long the system might have been sitting uncharged and possibly exposed to the atmosphere, but if it was R-12 there should be no issues as long as you remove ALL the refrigerant oil and recharge the oil as described in the FSM.  That would include the compressor and e sure and turn the compressor over a couple dozen times to prime the oil pump and lubricate the seal.
Then you leak check the system and if it is leak free, THEN you evacuate it.
In regards to R-414b, that is an excellent R-12 replacement but sadly one of its components is R-22 which is on the "kill" list so the cost has risen to that of R-12. 
Recycled R-12 is available in the US and since R-134a is also on the way out (all automobiles produced in the US since 2005 have used HFO-1234yf) R-12 is the choice by default.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

62 CDV


Greg,

You say that I should first remove ALL (your caps) of the refrigerant oil before checking for leaks and evacuating. Is there any other place in the system besides the compressor where oil needs to be accessed and removed?

Also, I've heard that the best way to know how much oil should be installed is by referring to how much was removed. Is this true?

Thanks in advance for the due diligence.

Ed

"Cadillac Kid" Greg Surfas 15364

Ed,
Remove AND replace the oil.  It should be distributed throughout the system. In the compressor, in the condenser, in the evaporator and in the dryer/receiver as well as in the refrigerant lines.
The FSM tells you how much oil should be re-installed in the various components.  Since the system will be opened it would be a good thing to replace all the o-rings at this time.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

62 CDV

Does removing and replacing all of the oil require a full breakdown and reassemble of the entire system?