1970 AC R12 or R134
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Joined: Mar 2007
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From: Warren MI
1970 AC R12 or R134
Getting ready to evacuate my AC system. Fresh system last year, everything new. Should I fill with R12 or R134 any advise would be helpful. I have never done any of this before would appreciate any help.
Team Owner
Joined: Jan 2006
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From: Crossville TN
Agree. If you have the system as was built at the factory, and/or part of the system already had R-12 and factory oil in it, you need to go back with R-12 and factory oil. The R-134a systems use a different lubricating oil in the system and those two oil types are non-compatible.
You can switch over to 134a if you want; but you have to purge/clean the entire system and use a different lube oil. Also, the original system using 134a will not be as efficient. And I think there are parts of the system that have to be recalibrated or have parts swapped for it to work at all.
You can switch over to 134a if you want; but you have to purge/clean the entire system and use a different lube oil. Also, the original system using 134a will not be as efficient. And I think there are parts of the system that have to be recalibrated or have parts swapped for it to work at all.
Last edited by 7T1vette; Apr 2, 2018 at 12:50 AM.
Thread Starter
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Joined: Mar 2007
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From: Warren MI
Agree. If you have the system as was built at the factory, and/or part of the system already had R-12 and factory oil in it, you need to go back with R-12 and factory oil. The R-134a systems use a different lubricating oil in the system and those two oil types are non-compatible.
You can switch over to 134a if you want; but you have to purge/clean the entire system and use a different lube oil. Also, the original system using 134a will not be as efficient. And I think there are parts of the system that have to be recalibrated or have parts swapped for it to work at all.
You can switch over to 134a if you want; but you have to purge/clean the entire system and use a different lube oil. Also, the original system using 134a will not be as efficient. And I think there are parts of the system that have to be recalibrated or have parts swapped for it to work at all.
Team Owner
Joined: Jul 1999
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From: Orange Park Florida
I live in FLORIDA for the last 21 years now, and if my 'careless' changes worked for 21 years here, I suggest it's no biggie......134 oil, and charge it.....
Melting Slicks
Joined: Dec 2009
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From: Thunder Bay
If its the original factory system, it will perform best with R-12 if you can get it.
Tech Contributor
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From: At my Bar drinking and wrenching in Lafayette Colorado
Lars
Last edited by lars; Apr 2, 2018 at 05:32 PM.
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Race Director
Joined: Jul 2015
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From: SW Florida.
R12 is pricier. have to have a licensed AC guy put it in. if your system is tight, it is worth the extra expense. if it leaks out every few weeks, go 134. shoot in a can, go to the get-together... for R12, check with HVAC guys near you. they use it too.
Last edited by derekderek; Apr 2, 2018 at 06:58 PM.
Tech Contributor
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From: At my Bar drinking and wrenching in Lafayette Colorado
R12 is still readily available. Worth the minor extra expense if your system is leak-free. I spend more on good Scotch in a week than the difference in cost between an R12 and R134 charge. In a couple of years, they'll decide that R134 is blowing holes in the ozone layer and causing constipation in Australians, and they will then mandate R167FP in all our cars. I have some that I will sell you in advance. 
Lars
Lars
Last edited by lars; Apr 2, 2018 at 08:06 PM.
Le Mans Master
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If your charging a system from zero, you want a vacuum pump and a scale. Weigh the exact amount you use and fill it to specs.
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Joined: Mar 2007
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From: Warren MI
You can't just put R134 in that system. Unless you specifically bought a compressor set up for R134, it more than likely has R12-compatible oil and o-rings in it. You need to flush your entire system out, and you may need to replace the expansion valve/orifice tube. It would be a good idea to replace the receiver/dryer. The service fittings will also need to be replaced.
Lars
Lars
Here is everything I put in new. Everything purchased from Paragon.
2473 AIR COMPRESSOR BELT-CUT STYLE
5770 HEATER CORE, W/A/C-REPLACEMENT STYLE-HEATER CORE, W/A/C
5785 AIR COMPRESSOR MOUNTING BRACKET-AIR COMPRESSOR MOUNTING BRACKET
11743 Blower Motor-BLOWER MOTOR
11752 A/C Evaporator Drain Tube Kit-A/C EVAPORATOR DRAIN TUBE
11766 A/C CONDENSER-A/C CONDENSER
11768 A/C RECEIVER DRIER-A/C RECEIVER DRIER
11772 A/C LIQUID LINE - W/ S.B.-A/C LIQUID LINE - W/ S.B. 111774 A/C Condensor Inlet-A/C CONDENSER INLET W/HOSE PROTECTOR
11775 A/C Dryer Outlet w/ Hose Protector-A/C DRYER OUTLET W/ HOSE PROTECTOR
11771K A/C MUFFLER & HOSE ASSEMBLY-A/C MUFFLER & HOSE ASSEMBLY
I have driven the car, but the compressor is not hooked up.
I looked and can't find out about the compressor, I will contact the auto parts guys tomorrow or Wednesday.
Drifting
Joined: Aug 1999
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From: Round Rock TX
Are you running the POA or the POA eliminator? That should determine more of what you run. You can get the POA calibrated for 134a, or to R12. I went 134a for my 70, and need to get my drier and condenser restored, which hopefully will be sent out this week. I’m going for original appearing yet functional.
Le Mans Master
Joined: Apr 2011
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From: Hermosa
Are you running the POA or the POA eliminator? That should determine more of what you run. You can get the POA calibrated for 134a, or to R12. I went 134a for my 70, and need to get my drier and condenser restored, which hopefully will be sent out this week. I’m going for original appearing yet functional.
A compressor does not care what Freon is in the system. However the oil that a compressor comes with may also dictate the “Freon” that is used.
If you are lucky it came with ester oil in the compressor as this is compatible with both 134a and r12 oils. Even if it didn’t just don’t mix PAG with mineral oil. It’s the oils that are not compatible. The various “Freons” do not care, that being said, r12 will not carry PAG oil well.
I would use ester oil (POE) to insure good oil carrying capability of either Freon and compatibility with any existing oil in the system.
I run ester in my system and a mix of r12 and 134a currently.
Office tube systems are sensitive to the size office tube used. The ford blue office is a good efficient one for 134a systems.
Lots of cooling air through the condenser is of paramount importance as well. That’s where the heat exchange takes place. You can’t ever get too much air through the condenser. Electric cooling fans are very good at this.
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From: Warren MI
Thanks for all of the input guys. My big issue is I don't know what oil is in the compressor. To make matters worse, I sold my house last year and had to move out of my big garage I had been in for 40 Years. Every thing went to storage in June. In October we closed on a new house with a much smaller 3 car garage and then it got cold. I am thinking that we are going to have spring some time soon here in Michigan, but so far we are stuck in the 30's and 40's. I will try to get a chance to look through some boxes for the paperwork for the compressor this weekend. I am not holding out a lot of hope of finding it, and I purchased it in 2013. I have 3 cars in the garage, but I have containers and shelves on all of the walls at least 1 row deep and 2 rows deep in many spots. I have never worked on an AC system, so I was not looking out for the right stuff.
Le Mans Master
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Thanks for all of the input guys. My big issue is I don't know what oil is in the compressor. To make matters worse, I sold my house last year and had to move out of my big garage I had been in for 40 Years. Every thing went to storage in June. In October we closed on a new house with a much smaller 3 car garage and then it got cold. I am thinking that we are going to have spring some time soon here in Michigan, but so far we are stuck in the 30's and 40's. I will try to get a chance to look through some boxes for the paperwork for the compressor this weekend. I am not holding out a lot of hope of finding it, and I purchased it in 2013. I have 3 cars in the garage, but I have containers and shelves on all of the walls at least 1 row deep and 2 rows deep in many spots. I have never worked on an AC system, so I was not looking out for the right stuff.
The new units have the green o-rings that work with either freon.
The 134 hoses work with R-12, but not visa versa.
If you flush the old cond. out properly, and use the correct parts, the 134 will work at 80% of R12 charge, but not as well.
That system was designed around R12 Freon. R134A uses a parallel flow cond.
You can go either way, but I changed my 81 over to 134A, and it sucked. I converted it back to R12, and it works great. I think it cools 10-15* cooler.
YOUR call.
Safety Car
Joined: Sep 2013
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From: Draper Utah
FWIW - I switched my 70 over to R134 and the AC has no problem cooling the car on a 100 degree day. The interior just isn't big enough to make cooling an issue. I have no clue how it worked with R12 as the AC didn't work when I bought the car.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
Sanden compressors (134a) are generally shipped with the required amount of PAG oil already in them. But, that may depend on the vendor.
In any event, you need to know if the compressor came with oil in it and what kind of oil it is.
In any event, you need to know if the compressor came with oil in it and what kind of oil it is.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
Here is an idea if your game.
PAG oil has a distinctive smell. Go buy a bottle of PAG and give it a whiff.
Now open you system at the compressor and give that a whiff. Same smell? There’s your answer.
Second question is still how much oil was in that compressor. The full charge?
When you put it on did you drain oil out of the compressor?
In my experience the compressor comes with an oil charge in it. Then usually you drain that out and put in fresh oil, sometimes all in the compressor and sometimes half in the filter dryer. In either case it is necessary to know the quantity of oil in the system.
PAG oil has a distinctive smell. Go buy a bottle of PAG and give it a whiff.
Now open you system at the compressor and give that a whiff. Same smell? There’s your answer.
Second question is still how much oil was in that compressor. The full charge?
When you put it on did you drain oil out of the compressor?
In my experience the compressor comes with an oil charge in it. Then usually you drain that out and put in fresh oil, sometimes all in the compressor and sometimes half in the filter dryer. In either case it is necessary to know the quantity of oil in the system.