1959 Cadillac Air Conditioning

[Joshua]

Hello Everyone,

I have a small problem.  I am restoring a 1959 Cadillac Sedan DeVille with factory air conditioning.  So far I have most of the parts replaced, however they seem to no longer make expansion valves for R12.  I have a new expansion valve, but it is stamped "R134a".  I have heard stories both ways saying that "it is fine, it will work, don't worry about it".  I have also heard "stay away from R134a expansion valves because they don't let enough R12 into the evaporator".  I am wondering if anyone has any experience in this area?

Thank you all so much,
Joshua Cross

[Scot Minesinger]

This is a heated debate, R12 or R134.  I would convert the whole car to R134, and many would stay with R12.  R12 does cool better than R134, no question.  However, R134 is much more serviceable and less costly.  Most garages do not have recovery machines to handle R12, and just about every garage has a recovery machine for R134.

The EPA fine for venting r12 is $25,000.  This can happen without a recovery machine.

On the subject of components use all R12 components or all R134 components.  There should be a good used R12 expansion valve or NOS out there - I hope.  Again a reason to change over to the dark side and use R134.  R134 has been identified as a greenhouse gas(same as CO2) and it will likely go the way of R12 in a decade.

On the 1971 thru 1976 Caddies I have changed them over to R134 with good success and no one complains that they do not have enough capacity.  However the 1970 and earlier I do receive complaints that on real hot days r134 does not cool as well as R12.  I drive a 1970 Cadillac convertible, so a/c is only on when it rains.  If is 110'F and sunny the top is down and a/c is off.

OK, I brace myself for the barrage of pro R12 fan comments.

["Cadillac Kid" Greg Surfas 15364]

Joshua,
You are correct about the (small) pressure and flow characteristic differences between R-12 and R-134a Expansion valves. I would suggest you do stay away from R-134a since with the hot gas bypass of your system (if it is to be just as the original) extremes of temperature and pressure will be very hard on your compressor and the rest of the system.  I would suggest you continue your search for an R-12 expansion valve, and I took the liberty of attaching the site below, Old Air who lists both the valve and the hot gas repair kit for your car.  There are several other ac Specialists (the general parts suppliers have to go to the AC specialists too), that should also have the correct  TXV (thermal expansion Valve).
"Hands on experience" yes. My practical and research experience (I wrote a series of articles that appeared in the Self Staqrter regarding the subject)  has proven R-134a CAN BE MADE TO WORK, however under the best of conditions at full load (hot/humid summer) a factory Cadillac AC system will loose 20-23% of its capacity if it has been charged with 134a instead of R-12.
http://www.oldairproducts.com/catalog/factory-replacement-parts/valves-ac-c-2_10000_10029.html?Make=Cadillac&Model=Car&Year=1959

That's enough of a rant from me for now.
Greg Surfas

[Scot Minesinger]

I agree with Greg's post and thanks for taking it easy on me.  The 12 cools better no question. 

[Eric DeVirgilis CLC# 8621]

Also, R12 is not nearly as prone to leak as R134a in a system designed for R12 - due to the smaller molecule of 134a.

I strongly advise keeping an a/c system original - if at all possible.

["Cadillac Kid" Greg Surfas 15364]

Eric,
If I am not mistaken, the R-134a molecule is lighter, but actually physically larger than the R-12 molecule. Actually the size of the R-12 molecule is taken as 3.95 (A) and R-134a molecules "measure 4.54 (A).
Greg Surfas

[Scot Minesinger]

It seems the strong recommendation is to replace the hoses w/barrier type for r134 conversions, and I always do that.  My R134 system has held strong for 8 years now-just like a regular car.

["Cadillac Kid" Greg Surfas 15364]

Scott,
New hoses are always nice, but very often unnecessary. You are "renewing" the system. "Barrrier" hose has an additional layer of material (nylon like compounds are best) to reduce the permeation of the refrigerant and is often recommended for  R-134a refrigerant. If one's A/C hoses have been in use and are not leaking and one converts to R-134a it is not necessary to replace the hoses. Apparently the mineral oil used in the R-12 systems has internally coated and permeated the material of  the hoses and stays in place since it is not miscible with R-134a refrigerant. This residual coating keeps the permeation of the R-134a within reasonable bounds. However, if a hose goes bad one should replace it with one made with the new barrier hose even if one is staying with R-12.
Greg Surfas

[Eric DeVirgilis CLC# 8621]

Eric,
If I am not mistaken, the R-134a molecule is lighter, but actually physically larger than the R-12 molecule. Actually the size of the R-12 molecule is taken as 3.95 (A) and R-134a molecules "measure 4.54 (A).
Greg Surfas

That may well be so - I cannot comment other than that was the reason given. Perhaps it was an oversimplification.

In any case, R134 is much more leak prone in an R12 system than R12. 

["Cadillac Kid" Greg Surfas 15364]

134a operates at a significantly higher "high side" pressure.  The oil pump (on an A-6 compressor) is fed from the high side therfore oil delivered to the shaft seal tends to "leak" more than with R-12.  "Barrier" hoses typically have a higher operating pressure limit which may or may not be a factor.  Mineral oil saturated o-rings do not react favorably with R-134a (they erode) so when you change the hoses, you change the o-rings, and a potential leak goes away.
Not trying to be a smart ass, but there is enough miss information out there, and the purpose of this forum is to pr4ovide factual information on the operation, functioning and repair of our Cadillacs.
Greg Surfas

[Scot Minesinger]

Greg,

My experience is that old rubber just is generally not worthwhile (seals, bushings, hoses, and etc.).  In fact the main thing we are doing with my son's 1970 Cadillac SDV with 32k miles is replacing everything rubber (along with steel fuel and brake lines plus timing chain) to cure the typical issues associated with low mileage 40 year old cars.  I know that many 40 plus year old refrigeration hoses hold a charge, but many do not.  Just finished working on a 76 Fleetwood and the thin hose from condenser to VIR failed and oil seeped out - it was quick and easy to fix.  I usually change the hoses out as a routine when working on older a/c systems.  I have the crimping machine and ferrles(spelling) so the old ends can be cleaned up and reused and just the rubber parts are replaced quickly and inexpensively.

I always replace the O-rings no matter what, even if the old hoses stay.

You have more experience than me on this hobby, but old rubber, cheap replacement parts, and bad mechanics haunt this hobby.  Plus as you say the new hoses do look nice.

Thanks,

Scot

[Joshua]

Thank you all so much for your advice and knowledge.  I am going to stick with R12 and see how it goes.

Thank you again,
Joshua Cross

[Joshua]

Hello again

On the subject of 1959 air conditioning.  Is there anyway to repair these vacuum rotary valves?  I have put in all new vacuum motors on the blower unit, new vacuum hose, and a new check valve.  These rotary valves on the air conditioning and heater controls are not holding vacuum and as a result the system does not have enough power to open or close the vacuum motors.

Thanks again,
Joshua Cross