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Original AC
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Ray
Posted 2016-11-10 10:11 AM (#525759)
Subject: Original AC


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Location: Fairfax, Minnesota

I am guessing that these units need to be converted to modern freon? What is the process?

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57chizler
Posted 2016-11-10 2:11 PM (#525778 - in reply to #525759)
Subject: RE: Original AC



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No "need", the original R-12 is readily available.
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plymouth
Posted 2016-11-11 9:58 AM (#525859 - in reply to #525778)
Subject: Re: Original AC



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I spent about $20 for an EPA license allowing me to buy R-12. I bought all the Freon I needed for my Imperial for less than $50.
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ttotired
Posted 2016-11-11 5:10 PM (#525894 - in reply to #525759)
Subject: Re: Original AC



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Basic conversion is to get as much of the original oil out that you can (just drain the compressor) and re fil with "Ester" oil, fit a new receiver/drier, fit R134a access ports and off you go

R12 is an outlawed gas in most of the world, why you guys can still buy it amazes me and yes, its a better refrigerant, but in automotive use, the difference between r12 and r134A is negligible.

This is the spot where you will now here "My aircon was so much colder on r12 than it is now on R134A" That statement always makes me smile, the gas (so long as it pulls below the thermostats coldest setting) really has nothing to do with how cold the vent temperatures are, that's what the thermostat does. It may take a second or 2 longer to get there, but that's it

In a true refrigeration sense, the whole system is not compatible to R134A and if it was a freezer trucks system, it would probably not pull down cold enough, but your car is not a freezer

Just on a side note, R134A is also going the way of R12 in that there was a world meeting of officials (I only 1/2 saw this on the news) and R134A is also going to be phased out over time to another gas that (I believe) is already being used in some Mercedes and some high end Japanese cars and its very expensive right now

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mstrug
Posted 2016-11-11 6:23 PM (#525898 - in reply to #525759)
Subject: Re: Original AC



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Then there is the ratio factor:

II. ACCEPTABLE OPERATING PRESSURE RANGES FOR VINTAGE AIR
SYSTEMS
A. R134A TYPE
1. HIGH-SIDE PRESSURES ( 160-250 PSI ) * Note- general rule of thumb is
two times the ambient ( daytime ) temperature, plus 15-20%.
2. LOW-SIDE PRESSURES ( 06-18 PSI in a steady state)
3. CENTER DUCT TEMPERATURE ( 36-46 DEGREES F.)
B. R12 TYPE
1. HIGH-SIDE PRESSURES ( 140-230 PSI ) * Note- general rule of thumb is
two times the ambient ( daytime ) temperature, plus 15%.
2. LOW-SIDE PRESSURES ( 12-15 PSI in a steady state)
3. CENTER DUCT TEMPERATURE ( 36-46 DEGREES F.)
Charge as follows: R134A = 1.8 lbs R12= 2.0 lbs
No additional oil is necessary in new compressors

9/10ths the volume using R134A
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57chizler
Posted 2016-11-12 2:53 PM (#526044 - in reply to #525894)
Subject: Re: Original AC



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ttotired - 2016-11-11 2:10 PM
R12 is an outlawed gas in most of the world, why you guys can still buy it amazes me and yes, its a better refrigerant, but in automotive use, the difference between r12 and r134A is negligible.


Only "outlawed" for new production, reclamation and possession are legal and there's no shortage....just look on e-bay.


This is the spot where you will now here "My aircon was so much colder on r12 than it is now on R134A" That statement always makes me smile, the gas (so long as it pulls below the thermostats coldest setting) really has nothing to do with how cold the vent temperatures are, that's what the thermostat does. It may take a second or 2 longer to get there, but that's it



A few seconds longer? This is where I notice the big difference in R-134 retrofits, the cool down time after a heat soak. Sure, the temp might eventually reach near the R-12 but it takes a LOT longer because the components in an R-12 system aren't matched to the R-134 efficiency.

The big problem with R-134 retrofits is leakage. Every automotive A/C system leaks to some degree but, since the R-134 molecule is smaller than R-12, it will leak at a much greater rate. Simply draining the old oil and recharging to 85% doesn't take into account the old leaking hoses and seals. Even when retrofitting to R-134, it's wise to have all the hoses rebuilt with modern barrier hose (quite expensive) and have all the seals replaced.

And then there's the old clunky compressor and the other components designed for only one refrigerant. Taking all this into consideration, the only savings are in the initial restoration of the dormant system and it's not that much.

Stay with R-12.
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ttotired
Posted 2016-11-12 4:50 PM (#526055 - in reply to #525759)
Subject: Re: Original AC



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You are right, it might take 2 years to leak out of the pores of the rubber hose instead of 4

It is illegal to buy or sell it here, it is to be reclaimed and sent for destruction

A system designed and built to use a particular gas is always going to out perform one that has been retrofitted, we went through all this over 20 years ago

Initial suggested retrofit procedure was basically to leave the evaporator in and replace pretty much everything else or it was supposedly not going to work. Period.

Over time, people (such as myself) experimented (I built a test rig) to try and see how much really needed to be changed. Bit like tuning an engine on a dyno and all my leak detection methods could not detect
any leakage from anything (this includes sniffers,dye and soapy water) and there were differences in performance with changing the TX Valve, condenser ect to R134a parts, but the R12 parts performed fine

I do know from experience that sooner or later, it will leak, but natural gas loss is supposed to be taken care of by regular servicing of the system

If a component fails, you replace it with an R134A compatible equivalent (if there is such a thing)

Of coarse I could go on, but I am only offering my opinion, I do not wish to get into a drawn out discussion on the merits of one way or another to fix a problem

Maybe, with how slow the US is in getting rid of R12, it could be used until whatever this new stuff is that we will have to deal with becomes cheaper

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57chizler
Posted 2016-11-13 2:33 PM (#526146 - in reply to #526055)
Subject: Re: Original AC



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ttotired - 2016-11-12 1:50 PM

You are right, it might take 2 years to leak out of the pores of the rubber hose instead of 4 :)



Not from my experience, I've seen old hoses that look like frying bacon when squirted with leak detection fluid.


It is illegal to buy or sell it here, it is to be reclaimed and sent for destruction



The OP is in Minnesota, not OZ.


Maybe, with how slow the US is in getting rid of R12, it could be used until whatever this new stuff is that we will have to deal with becomes cheaper


My point, if it ain't broke don't fix it.
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Mikeb
Posted 2016-12-18 11:51 PM (#529110 - in reply to #525759)
Subject: Re: Original AC


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I have had good luck converting both my 65 Plymouth Fury and a 65 Dodge Coronet but one more thing that has not been mentioned. You need to remove the EPR valve as it is not calibrated for 134. If your system freezes up you will need to add a thermostat wired in series with the compressor clutch.
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Chrispy
Posted 2016-12-20 6:35 PM (#529335 - in reply to #525759)
Subject: Re: Original AC



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Location: Colorado Springs, Colorado
the usual fix is a parallel flow condenser up front, these work better with 134A. The factory evap is so big in the factory A/C cars that i doubt you'll lose a lot of cooling performance with a better condenser up front.
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