News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

a/c repair of R12 system, what type of oil? and other questions

Started by Scot Minesinger, August 19, 2016, 09:59:00 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Scot Minesinger

Normally as you may know if I repair an a/c system, I usually convert it to R134.  However, I have agreed to try and fix an R12 system with R12.  The system failed because the high pressure compressor discharge hose rubber section failed and the entire charge was blown.  Right after, the owner protected the system so no moisture entered the system.

Questions:

1.  It could just be that the rubber was old, but I worry that the condenser may be partially blocked and I'm going to flush it.   What kind of oil do I buy to put back in condenser after it is flushed?  I don't want universal, want the type that would have been installed in mid 1980's.

2.  Not sure of history on this car, worried that "freeze 12" (same effect as r134, mixes with original oil and clogs components) was installed.  Does the clog or sludge blockage usually occur in condenser?

Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

dplotkin

To go from R12 to R134 you must flush the system of its existing oil and add ester oil. The compressor should be removed, drained of oil & partially refilled, adding the balance to the new dryer you should also install. You should NOT attempt to charge the system yourself unless you are trained, have the correct gauges/charging station and are wearing protective glasses at all times. System MUST be sucked down to 29 HG and then charged to 75% of its R12 capacity with R134. This is NOT do it yourself stuff. A blown high pressure line can spew refrigerant that will freeze your eyeball & cause immediate & irreversible blindness.

Dan
56 Fleetwood Sixty Special (Starlight silver over Dawn Grey)
60 Buick Electra six window
60 Chrysler 300 F Coupe
61 Plymouth Savoy Ram Inducted 413 Superstock
62 Pontiac Bonneville Vista
63 Chevy Impala convertable
63 Ford Galaxie XL fastback
65 Corvette convertable 396
68 Chrysler New Yorker

Scot Minesinger

The short thing is what non-universal oil do I buy for r12 (Ester is universal I thought)?  Is the condenser most likely place for a clog?

The system was never anything but r12, but worried that someone used "freeze 12" as a drop in replacement, when of course it is not.  I am getting the receipts to be sure no freeze 12 was added.  This would have been done in FL, which has a strong classic car and classic car a/c system repair shop net work as compared to other parts of the Country.

The a/c worked great until the hose blew off (either due to antique rubber, high pressure due to condenser blocked/restricted, or both).

I have an EPA card for refrigerant, am a multi-State licensed HVACR master mechanic, am a licensed multi-State professional engineer, and have repaired over a dozen system converting from r12 to r134 primarily.  This car is staying 12.  Never worked on a 12 system before, but have unclogged some condensers from bad r12 to r134 conversions completed by others.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

chrisntam

When I put my R12 system together, I used Tech Select brand "Wax Free Mineral Refrigerant Oil".  Says its for all R-12 automotive air conditioning systems.

Comes in a quart plastic bottle (like a quart of oil), there are two part numbers on the bottle.  Part No. 59000.  Part No. 209500

I don't recall exactly where I got it, maybe Old Air Products in Fort Worth?

I googled it and this is what came up:

https://www.summitracing.com/parts/fss-59000

1970 Deville Convertible 
Dallas, Texas

76eldo

Ester oil works.
Freeze 12 was compatible with r12 but it's hard to get now.

I'd flush the condensor out of the car and blow shop air through it.
Might not need more oil but of you add some it cannot hurt.

My personal experience is that the 12 works way better than the 134 in cars originally intended for 12.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

V63

If the system has an orafice tube...that's where the blockage is likely. Condenser obstructions are much more of an issue in late model cars with high efficiency condensers. Be sure to flush the existing condenser and monitor for contaminates and flow.

You need to flush the system anyway so you know where your oil level is at. inspect the oil for contaminates. At a minimum, Inspect existing compressor and its oil VERY  carefully! I would be VERY tempted  to just replace compressor clutch assembly at this time...especially if its an R4.

Replace dryer. Add and distribute mineral oil to specified amount.

Check engine cooling system! (Ie: fan clutch) Higher engine temps dramatically correspond to higher AC pressures.

dadscad

On the R-12 systems I've worked on, 60's - 70's GM, the usual blockage I found is from the dryer desiccant disintegrating causing a blockage of the screen at the expansion valve inlet. I've only seen one condenser plugged, on a 73 Chevrolet. It was so bad it caused the pressure relief on the compressor to pop off periodically.
Enjoy The Ride,
David Thomas CLC #14765
1963 Coupe deVille

Scot Minesinger

The a/c was working great on this car until the hose blew.  If the restriction (expansion valve/orifice) was clogged that could be part of the problem too - will at least clean screen to be sure.  Will replace drier too for sure (did not write that, but planning too do it).

One of the cars I fixed had a plugged condenser, so want to be sure we are good.

Thanks, I will buy the mineral oil.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty