HVAC guys... R12 vs. R134 and other A/C ?s

Doober

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Jun 2, 2003
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Catalina, AZ
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So since my '78 will be moving to Arizona to live with me eventually, it's getting A/C, no two ways about it. The closest place in Tucson to where I live right now that even touches R12 is close to an hour drive, so any time I would need it checked, serviced, etc., it would be a 2 hour round trip :shock: So I'm planning on R134, but I'm wondering if there is anything else I should use besides the stock setup. I did some reading on conversions... from simply dumping "R12-compatible" refrigerant in, to evacuating the system, making sure everything seals, changing the accumulator, and having a shop fill it instead of using those cans from WalMart.

I'm starting from scratch, meaning I have no hard parts besides the A/C firewall box and the wiring... I don't even have a heater core or blower fan :lol: My question is: are there parts different from the stock evaporator/condenser/accumulator I would need? I read about r12 and 134 using different oils, so I would get a brand new accumulator... but could I get the evaporator/condenser from a junkyard? Those are pretty pricey new - a quick guess on parts looking online is $240 without the compressor. I checked car-part.com for local parts, and the evaporator, condenser, and compressor together added up to less than $150. I also just saw something on RockAuto.com about orifice tubes for different climates... normal (under 105º) and severe (over 105º) - Tucson's typically hovered around 100º+ during the day during the hot season, would the severe climate tube be needed, or are we talking more "living on the equator" severe?
 

LS6 Tommy

MalibuRacing Junkie
May 15, 2004
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Just some background info.

1. There is no legal "drop in" replacement for R12 that can be mixed with it. There is stuff on the market, but it is not UL listed nor is it EPA approved, even if the maker claims it is. There are a lot of loopholes that these guys use to label their product "EPA Approved/Certified". Most of the time, the product IS EPA approved, but NOT for mobile HVAC use. DO NOT use any "refrigerant" that contains Hexane, Isopropane, Propane, Isobutane, Butane, etc. They are VERY flammable. Think minor front end accident. You could have a nice little explosion or at the very least there's a good risk of fire...

2. You will need a new receiver/drier. The new ones are usually compatible with R12 or 134a.

3. You will need a new orifice tube. Get one of the "self regulating/variable" ones if you convert to 134a.

4. When you get the hoses, oil & O-rings you should specify which refirgerant you intend to use. 134a is a smaller molecule than R12, so it will leak right through R12 hoses. You will need "barrier" hoses for 134a.

5. There is roughly a 20% capacity loss when you convert to 134a. when doing so, charge your system to 80% MAX of the weighed in charge of the R12, then adjust the charge from there.

7. When you get the compressor, if it has a relief valve it must be for the refrigerant type. 134a runs at higher pressures than R12.

8. You must use the proper High/Low pressure switch for the refrigerant you use.

9. If you get any used coils, flush them with the correct flush for your refrigerant before use.

10. After your system is all together, it must be evacuated (I would pull a vacuum on the system for at least 1/2 hour) before charging it.

Tommy
 

Doober

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Jun 2, 2003
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That's a lot of good info \:D/

#1 - I remember seeing something about no legal stuff that can mix with R12

#2 - Is this the same as the accumulator? My brain is saying the silver canister right next to the evaporator.

#7 - I don't know how many different compressors GM has used over the years, all I know is the serpentine setup is off an early/mid-'90s 4.3 Blazer, and my '92 had the same bracket setup on it... do you know if the compressors off newer cars that would've come with 134a from the factory would fit the bracket setup I have, or do they vary widely?

#9 - Do you think shops would charge quite a bit to flush the cores?

#10 - I would definitely have a shop do the charge and once-over to make sure everything works properly.
 

joynerz

Member
Aug 12, 2009
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Doober said:
That's a lot of good info \:D/

#1 - I remember seeing something about no legal stuff that can mix with R12

#2 - Is this the same as the accumulator? My brain is saying the silver canister right next to the evaporator.

#7 - I don't know how many different compressors GM has used over the years, all I know is the serpentine setup is off an early/mid-'90s 4.3 Blazer, and my '92 had the same bracket setup on it... do you know if the compressors off newer cars that would've come with 134a from the factory would fit the bracket setup I have, or do they vary widely?

#9 - Do you think shops would charge quite a bit to flush the cores?

#10 - I would definitely have a shop do the charge and once-over to make sure everything works properly.
Consider looking into "Vintage Air" or another aftermarket company to see if will work in your application. It's r-134a system, blows cold and is very reliable. Google it to see if you can find someone else who has done it. It's a few hundred bucks but by the time you're finished with sorting out an oem system you might have as much money as the aftermarket with less than desirable results. R-134a in a 80's Malibu is only just cool, not cold.
 

Doober

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Jun 2, 2003
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Well I don't have the money to spend on going to an aftermarket system, maybe some years down the road. I have a finite amount of time to get this thing road-ready and some semblance of working A/C. Anything is better than nothing, I have an '87 Fiero that currently isn't driven on hot days solely for the reason that there isn't working A/C.
 

LS6 Tommy

MalibuRacing Junkie
May 15, 2004
15,847
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North Jersey
joynerz said:
Doober said:
That's a lot of good info \:D/

#1 - I remember seeing something about no legal stuff that can mix with R12

#2 - Is this the same as the accumulator? My brain is saying the silver canister right next to the evaporator.

#7 - I don't know how many different compressors GM has used over the years, all I know is the serpentine setup is off an early/mid-'90s 4.3 Blazer, and my '92 had the same bracket setup on it... do you know if the compressors off newer cars that would've come with 134a from the factory would fit the bracket setup I have, or do they vary widely?

#9 - Do you think shops would charge quite a bit to flush the cores?

#10 - I would definitely have a shop do the charge and once-over to make sure everything works properly.
Consider looking into "Vintage Air" or another aftermarket company to see if will work in your application. It's r-134a system, blows cold and is very reliable. Google it to see if you can find someone else who has done it. It's a few hundred bucks but by the time you're finished with sorting out an oem system you might have as much money as the aftermarket with less than desirable results. R-134a in a 80's Malibu is only just cool, not cold.


#2- Yes. My mistake. For some reason the auto industry terms that an accumulator, but technically it's a receiver. An acuumulator is on the outlet of the condenser. A receiver is on the suction line just before the compressor.

#7- the compressor itself doesn't know or care what refirgerant type it's pumping. Just make sure the relief valves, drier, orifice tube, oil & pressure switches are correct for the application.

#9- You can get the flush at most automotive parts stores. Just remove the coil/hose/whatever, blow this stuff through, air dry. Reinstall, evacuate, charge...

Tommy
 

LS6 Tommy

MalibuRacing Junkie
May 15, 2004
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Doob- I must be getting old... I had the terms backwards, not the auto industry (gee what a surprise LOL)... It is an accumulator, not a receiver. It's been a LONG time since I had to look hard at the technical end of the refrigeration cycle...

Tommy
 

gmtofd

Dragway Regular
Jul 16, 2004
716
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Central Jersey
My son has been maintaining the ac on our 3 daily driven g bodies for about 10 years and have the following observations:

Better off getting a brand new compressor.

If your going to convert to R134, spend the $ on getting good hi/lo adapter valves. He generally gets them from NAPA although Rockauto may also sell better quality valves. Always have the caps in-place.

Spend the extra $ on good refrigerant oil, that contains a dye(forget what the brand is, but it begins with a "E").

Spend the extra $ and get a OEM style accumulator. I believe in Rockauto, they are listed as AC/Delco. The genaric accumulators, have an extra fitting which is another source for a future system leak

After conversion or getting the system back on-line if retaining R12, inject a can of Super Seal to prevent future leaks. There are a number of these on the market, and will have to check which one we use.

The Malibu was converted to R134 about 5 years ago, retained the old lines, located a brand new compressor , and flushed the condensor, eval with acetone, blowing out with compressed air. The system works okay, but not as good as my son's system in his Cutlass that is still running R12. One thing that would be a definite improvement to system efficiency is an electric fan, which is why on newer cars with dual fans, when the a/c is turned on, so is an electric fan drawing air through the condensor. It especially helps when at a stand still.
 

elcaminoss84

Frequent Racer
Sep 26, 2009
336
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Oklahoma
I just finished my ac system/ serpentine setup. I used parts for a 94 chevy truck ac compressor, powersteering pump , water pump , alternator, clutch fan assembly. then used the main line to compressor from a 88 s10 blazer , the small metal line off of a 84 cutless and condensor from a cutless since the lines are on the passenger side. then used my drier and evaporator from my el camino.
 

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