A/C Conversion R12 --> R134A

e21pilot · Mar 29, 2015

My 1992 4.0 can with factory A/C but I seldom used it and now it doesn't work at all. I suspect there are a few leaks in the hoses now that they are 20+ years old.

I was thinking of repairing the leaks but was surprised to see how expensive R12 has gotten these days.

Maybe it's time for the conversion to R134A? Am I correct that all the same A/C components in my 1992 were used in say a 1995 4.0 Ranger which came from the factory with R134A. If so, it sounds like all I need to do is clean the system out, replace all the hoses. add adapters for R134A and then add the R134A and I would be done?

Is it really this simple?

I've been told to upgrade to the more modern (less flexible) hoses as they are less likely to leak the smaller molecule R134A. If this is true, is there a source for these more modern hoses for an early 4.0?

Mazda · Mar 29, 2015

As far as I know you cant even buy R12 without a license.

It's probably best to take it to a shop and at least have them fully evac the system.

Fix the leaks yourself and be sure you put in a new orifice tube in it.

Go back to the shop and then have them dry the system and refill with R134.

It really isn't that simple when you have something that old and that you haven't used that much anyway. It's really easy to lock up your compressor after it has sat that long not working.

I know it's a lot more money taking it to the shop but might be the better way to go.

e21pilot · Mar 29, 2015

I like the idea of doing much of it myself but right now I've got no time to turn wrenches. Instead I might just source the right parts so the shop has a reasonable chance of success.

Speaking of parts, it seems the compressors were the same for both the R12 and R134A years on the 4.0 Ranger motors. This is interesting.

I wonder if I can just have my old compressor cleaned out, than replace the hoses and accumulator with something for a 1997 Ranger 4.0 which would have the correct hi and low pressure fittings and probably be made of the better host style intended keep the R134A in the system rather than leak out.

I wonder if anyone knows if it would be easy to retrofit these 1997 parts with my factory original 1992 compressor, condenser and evaporator? If so, that would make this job much easier and probably result in more reliable system at the same time.

4x4junkie · Mar 29, 2015

All new hoses made today are R-134a-compatible, so there should be no worries there.

I have read that an older R-12 compressor is fine on 134a AFTER it has seen some use with R-12 (something about the R-12 molecules coat the surfaces or harden them or somehow make it so that it can be safely used with R-134a). I have not looked real deeply into how true this is since I was planning on replacing mine anyway, though I do know R-12 comps have been reused successfully with R-134a.

However there's a very good chance your 23-year-old compressor's seals have seen better days, so you might want to replace it anyway (in which case you should be getting a fully 134a-compatible component there as well).

I converted my '90 BII to R-134a about 7 years ago (new hoses & related, new Visteon compressor. Condenser and evap are still the OE ones).

Thread here:
http://www.therangerstation.com/forums/showthread.php?t=21719

Mazda · Mar 30, 2015

4x4junkie said:
I have read that an older R-12 compressor is fine on 134a AFTER it has seen some use with R-12 (something about the R-12 molecules coat the surfaces or harden them or somehow make it so that it can be safely used with R-134a). I have not looked real deeply into how true this is since I was planning on replacing mine anyway, though I do know R-12 comps have been reused successfully with R-134a.
http://www.therangerstation.com/forums/showthread.php?t=21719

I converted my 94 system to R134 in 2004. No problems what so ever. Has been recharged only once I believe I did it in 2011. Kind of pissed me off because it only used a little bit of the can and here in California you have to pay $10 deposit on the can and have 30 days to get you deposit back. You can tell though if you are used to r12 that it sure isn't as cold as it was, but hey truck cab isn't that big to cool down.

sblake01 · Mar 30, 2015

Mazda said:
You can tell though if you are used to r12 that it sure isn't as cold as it was, but hey truck cab isn't that big to cool down.

If you change your condenser from the R12 serpentine type to the R134a parallel flow type it would be as cool if not cooler with R134a than it was with R12.

4x4junkie · Apr 3, 2015

I was getting 38°F out of my vents right after the conversion (OE condenser). Much colder than that I think the evap would start icing up.

Lately it does seem to have warmed up a very slight bit though (maybe 45° I'm guessing without having stuck a thermometer down in the vent). After 7 years I s'pose a small bit of 134a could be added back into the system.

A/C Conversion R12 --> R134A

e21pilot

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Mazda

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e21pilot

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4x4junkie

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Mazda

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