Engine Size: 173
Refrigerant Type: R 134a
Ambient Temp: 79ÃÂ°F
This was originally a R12 system with GMs DA-6 compressor. Converted to R134a only by vacuuming the old gas.
1. Belt is slipping momentarily when the compressor kicks in. Belt tightness is proper. Apparently compressor put more drag, I wasn't feeling when it kicks in or out when everything was proper. Drag is also variable at times clutch remainig engaged.
2. Compressor cycles are shorter than it used to be.
3. Does not cool as well, although still acceptable. I worry for the compressor.
I. Two years ago a place charged 1kg. R 134 (system capacity for R12 is 1.24 kg) with an automated unit, never idled car's compressor during charge.. Did similar weird things, and wasn't cold but only cool.
II. Last year I went to another place with basic contrivance who vacuumed for long, charged by idling the car without any real measurements. Measured 2ÃÂ°C in the middle duct (original spec is 4ÃÂ°C). Did awesome throughout the year, and just behaved normal as originally, even a tad cooler.
III. This year I went to the same place with basic gadgets. They did everything exact but just a little quicker I guess. Although they cleaned the condenser this time, duct only reads 4.9ÃÂ°C. I thought it is almost spec and left. After leaving I discovered we're again back to the square one.
I'm thinking on returning to the same place for correcting this but not sure they're great at diagnosis. Is the system undercharged, overcharged or this is just the quality of the gas? Or lack of lubricant this time may be?
any input is appreciated
The compressor is probably dying from lack of oil. See if it turns freely by hand. The oil needs to be changed to use R-134a. Some sump type compressors will work for quite a while with the old oil, but eventually it will leave the compressor and the R-134a does not mix with it to push it back around again.
i had a ford f150 that was r12 and i switched to r134a and it didn't like it at all and wouldn't cool so i had to have all that evac out and put in freeze 12 and alter to r12. after that i had no more problems out of the a/c, however i did start having transmission problems and later traded for something else.
sometime afterwards i bought a ford bronco and it was low on freon and wouldn't cool, didn't even bother with r134a and went straight to freeze 12, never had a problem, i just don't think these conversion kits are all they're cracked up to be.
thank you for the answers
Last summer this system worked awesome with R-134 which I wasn't expecting, but it did . But I just don't know the exact weight of the gas since this was done by basic gage manifolds, upside down tube and by reading the inside temp till 2ÃÂ°C / ~35ÃÂ°F. Afterall this is not a real conversion and I was expecting to lose the "thinner" gas during winter. Prior to this comp. again acted weird so at least it is not degrading in a trend.
DA-6 doesn't have oil sump, so that in case an oil change, service manual advice not to bother draining and metering oil in the comp. And I was mistaken for the spec. It is actually 1 to 6ÃÂ°C per the service manual up to 101ÃÂ°F ambient. Ambient temp. is not that hot yet, just 78ÃÂ°F, so maybe we should be closer to the 1 rather than the 6 ?
Indeed it feels like lubrication error... but not just it I think (why so many cycles). This morning I monitored 4ÃÂ°C at the duct in the stop-go traffic. No jerking/chirping while clutch kicking in, very rare cycles. It looked stabilized. But once on the open road it was again a hard (for compressor) engagement and many cycles... so I turned it off not to cause damage.
May be the oil needs re-sucked from the accumulator since it was sitting for a while? I tend to beileve a little less than adequate gas put so it is lacking to carry the oil properly... Does this comment hold any water? I'm asking this because I want to revisit the shop to top off the gas a little more. Also they revved the engine at the end of charging so may be it took more gas than it should?
1. Recovering R12 and recharging with R134a is not a proper retrofit. The R-134a will not move the mineral oil adequately and the entrapped R12 molecules remaining in the mineral oil can react with R134a and begin to congeal (thicken) the oils making it even that more difficult to migrate.
2. You are needing to add refrigerant too much. You have a leak that needs to be found and fixed.
3. You have provided no pressures. High side may be spiking and causing cycling. This could be condenser air flow, internal restrictions (congealing oil), or faulty cycling switch, etc.
4. R134a molecules are "thinner"; is a myth.
5. Freeze 12 is another "lets not fix it right, lets use this" product. Just because someone survives a fall when the chute does not open; should we all jump out without a chute?
Minimum, this system needs to be cleaned to bare metal and properly converted to R134a or recharged with R-12. New filter & orifice and the proper oil and amount should be installed for the refrigerant chosen. The leak should be found and fixed. Then proper diagnosis of the cycling issue (if it is still present) can be performed.
Last year I scanned this board and learned/realized many things. Also some knowledge interferance for a novice if you seek too much in a little time over the net, expect me to inherit some myths, that's why I'd quote.
As I now realise oil compatibility is really important. May be because it "seemingly" functioned flawlessly last year with new refrigerant I started to feel lucky. Frankly I put aside all the data because practically it worked flawlessly. But we lose the base for maintenance and don't know why it worked then and not now...
Leak is probably the shaft seal of the compressor because the clutch gets oily. I'll special order a POE oil and follow SAE recommendations (any copies on the net?) and opt for R-134a %5 less by weight. Service manual states 525 viscosity, is it still the viscosity for the 134 refrigerant? Would add on filters/mufflers reduce the performance (Delco's own kits) ?
First you have a leak somewhere, before starting it would be good to use the refrigerant that's in there to try and find it. R-134a is not a "thinner" gas than R-12 and if your system is properly tight for R-12 it will hold R-134a as well.
Remove the refrigerant and check the OT. If it has black stuff or lots of metal (a few flecks can be disregarded) on the screen, the compressor is coming apart. Also if the compressor is balky to turn by hand it is probably about to seize up, even if it does get some oil, so should be replaced.
Since it's an old car you may not want to put a lot of money into it, and take the risk of failure by shortcutting what ought to be done. Still I would suggest at a minimum you remove the compressor from the car, drain it and flush with POE oil, and replace the accumulator/drier. These two parts hold most of the oil during operation. Then install the specified volume of POE oil, same amount as mineral would be used. Evacuate and recharge. You should work up the charge slowly starting with 80% of the R-12 amount, but it may take the full amount. Going over the specified amount with R-134a is certainly an overcharge. Write down the amount charged in case it is necessary to do it again.
The only POE that's readily available to us in the USA is 100 viscosity. It is suitable for conversion jobs where mineral 500 or 525 was previously used. They are different viscosity scales.
As I recall the DA6 was not an acceptible candidate for conversion, and this led to the production of the HR6.
This car was never properly converted anyway, and the compressor is likely junk now.
Complete flushing of the individual components, a fresh HR6 compressor, new accumulator, proper oil charge - and you should be ready to evacuate & charge.
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
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