R134a retrofit?

Jul 03, 2003 20 Replies

What is the procedure nowadays? When I did my '84 Chevy truck, I pulled the compressor, changed to the new oil, evacuated the system, then recharged with 134a (with equal to or better than R12 results).



I have heard of people just removing the R12, evacuating, and recharging with the 134a, using the old R12 oil.



I have a relative who changed to the new oil, but didn't bother to evacuate before charging with 134a, and his truck (89? Ford) seems to work fine.



The vehicle in question is not a Chevy truck, but my '90 Geo Metro. It needs a shot of freon, and with the cost of R12 being so high (I'm licensed), it is finally time to retrofit, and I'd like to do make sure the compressor won't have any oil issues.



Input?


Do a google search on alt.autos.camaro.firebird for 134a, response posted a day or so ago by CBHvac. He owns a HVAC company and knows his stuff. That thread will give you all the info you need, and then some.

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98 Camaro

Buddy of mine just had an r-12 car system "topped off" with R134a. Works fine.

I never would have thunk it.

db

Wow...

Interesting read. Anyone know how long before 134a becomes "controlled"??

Thanks.

db

Don't ask me. CBHvac and I have been in the same group for years. I just trust his judgement. He knows his stuff. His company is carolinabreeze.com.

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98 Camaro

probably for a while it will be ok. It took the EPA something like 15 years to phase out R-12. I really want more information about his idea of using

410a as a coolant to top up a R-12 system. I don't remember anything about R-410a (Puron) having the same properties as R-12 (Freon). It's also interesting that he says R-12 is $30 per pound...

mark

site about puron--->

formatting link

Yeah, $30 a LB for R12 is radical in my neck (like $80 in OH), but he does know his stuff. Just post to him and he will give you the info you need. Trust me, he is a great and knowledable guy. I would not toute him if he was not.

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98 Camaro

"controlled"??

cb is a HOUSE ac guy,,,,, find my posts on the subject.... Automotive AC is what i do

: > I have heard of people just removing the R12, evacuating, and recharging : > with the 134a, using the old R12 oil. : >

: > I have a relative who changed to the new oil, but didn't bother to : evacuate : > before charging with 134a, and his truck (89? Ford) seems to work fine. : >

: > The vehicle in question is not a Chevy truck, but my '90 Geo Metro. It : needs : > a shot of freon, and with the cost of R12 being so high (I'm licensed), it : > is finally time to retrofit, and I'd like to do make sure the compressor : > won't have any oil issues. : >

: > Input? : >

: >

: : :

That's new. I always thought the two freons were incapatable, and they should never be mixed...

CFC (r-12) is based in chlorine (hence the supposed reaction with the ozone in the atmosphere----- r-12 has never been proven to harm ozone). HFC (r-134a) is not based in chlorine, and should never be mixed with r-12 in a refrigeration system.

Most retro kits did not work as well as OEM systems do now, since 134a requires MUCH less to cool the same amount of air (hence more energy efficient). When recharging the AC system on my old 86.5 nissan hardbody it took several pounds of r-12 (with only topping the system off), and (assuming memory serves) my 2001 honda crv requires less than a pound of

134a.

the major difference between the two according to my instruction was the size of the tubing in the entire system, r-12 needed larger tubes than 134a, and attempting to use the r-12 "legacy" type evaporator/condenser units in addition to the compressor... depending on how much you love your car, I would consult the dealer for info about new evaporator/condenser/compressor set to really use the system wisely.

as for r-12... if you burn it, you have made mustard gas.... arent you happy we dont have that available for saddam and ossama?

it's not that they are incompatible, it is that the vapor pressures are additive

say you have 90 degrees ambient, the R-12 is at 150 psi leaving compressor, the R-134a is at 250, you end up with 400 psi

compressor,

you are not talking 'air + air '

you are talking about two vapors, each with it's own pressure

and they add to each other

Guess I started a "good" conversation... I'm still wondering how I should attack my problem.

change accumulator, orifice tube, add about 4 oz of new oil to make up what was in the accumulator, pump it down and recharge until you get about 50 psi on the low side, watch vent output temps, when it gets down to about 40-45 on 'Max Air', fan on hi, windows closed, you are done.

you will probably have to block the throttle to about 1500 rpm, and set up a box fan to blow air thru the condenser while charging it

watch the high-side pressure, it can rise pretty quick, try to keep it under

250 or so

one thing.....high-side pressures with R-134a can climb to over 400 is you don't keep air moving thru the condenser..........watch out

The burning of R-12 does not produce mustard gas, it produces phosgene gas. While both phosgene gas and mustard gas were used on the battlefield during WW1, mustard gas was used later as it was found to be a much nastier blister agent than phosgene. Today, phosgene is used in the manufacturing of plastics and pesticides. It's very low, if on the list at all, on the Muslims wish list for an agent to be used against us.

Rita

it produces phosphene gas, not phosgene (mustard) gas

nope

burning R-12 creates phosphene gas

mustard gas is phosgene gas

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