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A/C conversion

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Old Jun 2, 2006 | 07:53 PM
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Default A/C conversion

Can anyone tell me the proper way to convert my 81 to R-134. Have heard all types of methods and tales. It currently has R-134, but I think the previous owner must have missed something. It cools but not good. Help!
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Old Jun 2, 2006 | 08:54 PM
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If you don't have an adjustable cycling switch you need to get one. You need to cycle at a lower pressure w/ R134a.

Also replace the stock orifice tube with a "smart VOV" (google for it). With those two changes, and if the rest is in good stock consition, your vent temps should be in the lower 40's even on a hot day. You can get an AC thermometer at any parts store for $5 or so to verify.
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Old Jun 2, 2006 | 09:43 PM
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Originally Posted by zwede
If you don't have an adjustable cycling switch you need to get one. You need to cycle at a lower pressure w/ R134a.

Also replace the stock orifice tube with a "smart VOV" (google for it). With those two changes, and if the rest is in good stock consition, your vent temps should be in the lower 40's even on a hot day. You can get an AC thermometer at any parts store for $5 or so to verify.
Could you expand on the "adjustable cylcing switch" part?
I bought a kit a few years ago that basically just had some adapters for the hose fittings and a can of R134. Was that not enough?

Thanks!
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Old Jun 2, 2006 | 09:52 PM
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I hope you didn't just bleed off the R-12 & juice the system with R-134. The compressor oils are not compatable between R-12 & R-134. There are some oils & refridgerants that go both ways, but you specificly have to replace the original oil.
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Old Jun 2, 2006 | 10:22 PM
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Originally Posted by jlelec
Can anyone tell me the proper way to convert my 81 to R-134. Have heard all types of methods and tales. It currently has R-134, but I think the previous owner must have missed something. It cools but not good. Help!
Check out this tech artical from zip. It might help you retrace the system to see if something is missing.

Zip 134a Conversion Artical
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Old Jun 2, 2006 | 11:04 PM
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Originally Posted by adamw1979
Could you expand on the "adjustable cylcing switch" part?
Your stock system has a cycling switch. When the AC is on the compressor will run for a while and then shut off, then back on etc. The switch will shut the compressor off when the pressure goes below a set value. The optimal pressure for cycling is lower for R134a than R12. Some factory switches are adjustable, some not.
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