Converting R12 to 134: a problem
07-30-2009, 02:22 PM
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Converting R12 to 134: a problem
Sorry for the dumb A** post. My '89 S2 no longer cools so as it went down slowly over a couple years I assumed it was a lack of coolant. I purchased the R12 conversion kit, put the threaded adapter on the low pressure line near the strut, and the guage from the kit measured "0" for pressure. I then put about a 1/4 can at most of the 134 refrigerant and the guage measured into the "danger" zone with a value of "70". So it seems something is off. I have the switch on and full cool, but still warm air. Now I'll sound totally clueless and ask how I know if the compressor is on? What line of testing next? I could spend time going over manuals..etc and searching but I'm at work, hoping for some replies to maximize my time tomorrow evening when I look closer at it. Thanks in advance.
07-30-2009, 08:21 PM
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The compressor is on the bottom right if you are facing the front of the car. The belt will spin around the compressor but the center of the compressor will be stationary when the compressor is off. The compressor is on when the center of the pulley is spinning with the belt - you will hear an audible "CLICK" of it engaging - possibly some fluctuations in RPM of the motor. Odds are it wont kick on, because you dont have enough refrigerant in there. The system is protected by a low pressure cutoff that wont turn on the compressor in a low pressure condition.
Some questions:
Did you vacuum the system out before you put the R134a in? Did you get the mineral oil in the R12 system out of all the devices, and put in the correct amount of ester or equivalent oil? Did you replace the dryer? Did you replace all the R12 o-rings for R134a ones? Did the can get icy cold while you were putting it in?
It sounds as if you also did not install your threaded adapter correctly, or there is a problem with either the R-12 fitting thats brazed onto the low side, or the threaded 134a fitting. Are you sure you are putting in refrigerant on the LOW SIDE!!! You said it leaked down slowly over time (2 years) so it is likely there is still R12 lingering in there (at least 5-10psi) worth on the low side. You then barely put a can in, and it says 70psi? Sounds like none of it made it through the R12 valve and is trapped between the adapter valve and the original.
Some questions:
Did you vacuum the system out before you put the R134a in? Did you get the mineral oil in the R12 system out of all the devices, and put in the correct amount of ester or equivalent oil? Did you replace the dryer? Did you replace all the R12 o-rings for R134a ones? Did the can get icy cold while you were putting it in?
It sounds as if you also did not install your threaded adapter correctly, or there is a problem with either the R-12 fitting thats brazed onto the low side, or the threaded 134a fitting. Are you sure you are putting in refrigerant on the LOW SIDE!!! You said it leaked down slowly over time (2 years) so it is likely there is still R12 lingering in there (at least 5-10psi) worth on the low side. You then barely put a can in, and it says 70psi? Sounds like none of it made it through the R12 valve and is trapped between the adapter valve and the original.
07-30-2009, 09:59 PM
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Oh boy. Thanks for the feedback. The conversion kit says the adapter ONLY screws onto the low pressure side. I asked the guy at the store (Napa) and he said just put on the adapter, if there's no pressure, just "empty the cans in there, easy as that". Should have known. Did not do any else of the things you mentioned so I'll start searching this forum for more information. I never do things half assed but it's so hot wanted to get a little cool on the way to work. Thanks.
07-31-2009, 12:42 PM
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A general search of how to convert the refrigerants will reveal what to do, but it is alot of work to go to 134a and it too will be phased out in the next decade for R410a. Might consider Freeze-12 instead which is flammable - but compatible with R-12 and the oil R12 uses. It should be directly feedable to the system.
I dont like the conversion method, as R134a is not as efficient and requires a bigger condenser for an equivalent temperature drop. Its head pressure is higher, so it is harder on the compressor, and pulls more load off the engine. R134a doesnt carry oil as well through the system as R12 and R22 do. R410a will be one step worse of a refrigerant, but will be more environmentally friendly than R134a or R12/22. That Freeze-12 has a lower head pressure even than the original R12, meaning less work for your compressor, only catch is its really flammable (isobutane I believe).
Good luck! I long since removed the A/C completely on my 944!
I dont like the conversion method, as R134a is not as efficient and requires a bigger condenser for an equivalent temperature drop. Its head pressure is higher, so it is harder on the compressor, and pulls more load off the engine. R134a doesnt carry oil as well through the system as R12 and R22 do. R410a will be one step worse of a refrigerant, but will be more environmentally friendly than R134a or R12/22. That Freeze-12 has a lower head pressure even than the original R12, meaning less work for your compressor, only catch is its really flammable (isobutane I believe).
Good luck! I long since removed the A/C completely on my 944!
08-12-2009, 06:20 PM
#5
A Porsche mechanic did the conversion on my C2 Turbo and the thing is working great...He drained and replaced the oil,changed the receiver/dryer,changed few O-rings and viola...cold air once again...
