R-134A retrofit

4x4junkie · Jul 13, 2008

So I've decided I'm going to fix the A/C on my '90 BII rather than yank it all out (was just reminded that driving through California's central valley in smoky 105° weather (from the fires) isn't exactly pleasant lol).

I've done a bit of reading on this, looks like I'll need at minimum a:
retrofit kit,
O-ring kit,
new dryer,
orifice tube,
replace the pressure switch,
and drain & flush out any remaining R-12 mineral oil in the system and then evacuate it.

I think I also want to replace the compressor (has oily deposits all over it, I suspect it's the source of a leak), and maybe all the hoses (they appear to be original almost 19 years old, although I don't really see any significant cracking on them, would they hold 134A?). I'd also like to upgrade to a bigger condenser for the 134A as well, if possible (would one from say, a '95-'97 Ranger fit up front?).

Anyone done this themselves and have an idea what I'd be looking at cost-wise with all this? Anything I'm overlooking?

Ranger44 · Jul 13, 2008

Seems like you've got evrything. I've been thinking of going back to A/C.....

Don't forget about the article in the tech library:

http://www.therangerstation.com/Magazine/June04/tech.htm

RobbieD · Jul 13, 2008

Sounds like you've got it nailed down pretty good. I did the same thing on my '90 B2, and it's not a bad idea to spring for the new compressor and hoses, if you can. I can't tell you for sure about the later condensor ('94 up for 134A) fitting the second gen B2, though; I reused the original on mine.

MAKG · Jul 13, 2008

You don't really need to replace the pressure switch unless it's bad, but it isn't very expensive.

If the compressor is leaking behind the clutch, it MAY need to be replaced. If it's leaking at the manifold, it probably just needs an O-ring or two (depending on which type you have). Compressors are expensive, so I'd look into this.

Base your decision on how to proceed on the orifice tube, and the results from flushing. If there is a lot of crap in there, you may want to replace the condenser.

AllanD · Jul 15, 2008

As for hoses the 2.9's installation is pretty much unique to the 2.9.

The condenser from any Ranger up to 1992 or explorer through the end of 1994 can be made to fit, but only if you use late 91 or 92 2.9 hoses.

Basically the later system gets by with one less connection in the system.

IMO this can only be a good thing.

AD

MAKG · Jul 15, 2008

The later system has one bolt holding the single compressor manifold on. Which, in practice, has to be overtorqued to keep from leaking, even with a brand-spanking-new O-ring and verified flatness (with R-134a on a hot day, it can easily be asked to hold back 250 PSI). And it's threaded into aluminum (not good for overtorquing).

The older one has two bolts on EACH fitting. I like this quite a lot better.

But then again, new compressors are 10 cylinder, as opposed to the older 6.

4x4junkie · Jul 15, 2008

Alright, thanks for the info.

I had read that 134A needed to run at a higher pressure than R-12, so that's why I mentioned replacement of the pressure switch. (and similar for the condenser, it needed to be bigger to have the same cooling capacity as with R-12, due to R-134A's lesser efficiency).

I guess I'll take a closer look at the comp's manifold seal and start collecting parts together then.
(What makes the later Ranger condensers not fit? I ask because the radiators themselves would swap perfectly between my '94 Ranger and the BII. Is it fittings?)

MAKG · Jul 15, 2008

The pressure switch lives on the low side. R-134a CAN run at the same low side pressure, but you can also get away with LOWERING it some, to, say, 20 PSI. The lowest pressure that doesn't ice the evaporator is what you want here.

Jspafford · Jul 15, 2008

I know this won't help you any, but I had the dealership change mine.

I took it in for something and they ended up not charging me, so I told them to fix the A/C. They bleed the old refrigerant out, replace an o-ring, and recharged it with the new stuff, that's been two years ago and it still works good!

When I got the truck it didn't work, it is niiiice.

Wicked_Sludge · Jul 15, 2008

wally world sells R134 retro kits for $10.

you dont NEED to replace anything other than installing what basically amounts to adapters to the high and low side service ports. most people believe you HAVE to replace o-rings, but the R12 seals will hold up just fine if they arent already leaking.

Jspafford · Jul 15, 2008

Wicked_Sludge said:
wally world sells R134 retro kits for $10.

you dont NEED to replace anything other than installing what basically amounts to adapters to the high and low side service ports. most people believe you HAVE to replace o-rings, but the R12 seals will hold up just fine if they arent already leaking.

Hence the reason the A/C stopped working. It lost all it's charge and would not even kick the compressor on.

Wicked_Sludge · Jul 15, 2008

obviously if the rings are shot, they need to be replaced either way.

my point was that the r134 isnt going to desolve the original r12 rinmgs or anything like that.

MAKG · Jul 15, 2008

Those cheap retrofit kits come with AC-Plug (oh, I meant stop-leak).

Remember whatever you put in your A/C is going to be there forever. Even long past its usefulness.

Old stop-leak = circulating garbage.

Wicked_Sludge · Jul 15, 2008

mine didnt come with any mechanic in a can...just the service port adaptors...nice and simple.

installed them on the escort. i had to go through hell to undo almost 20 years of neglect on that air conditioning system...but it blows cold now :wub:

MAKG · Jul 15, 2008

OK, $10 is reasonable for two adapters.

But frankly, you DO need to do something about the mineral oil. That's also circulating crap.

There is a "right" way to do this. Which is what you do if you want it to last. Other shortcuts represent risks, and I won't recommend them to anyone because of that. Perhaps it will be OK if enough of the mineral oil made it out and the compressor wasn't TOO bad and so on. But you can't possibly know that.

Not evacuating prior to charging is considered highly unprofessional. It will lose you some function, perhaps quite a lot of it.

Frankly, if the O-rings aren't leaking, the correct solution to the retrofit is to do ABSOLUTELY NOTHING. If it ain't broke, don't fix it. If it has an electrical problem, same deal. This means there is no legit use for that service kit (at least, not by itself).

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