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Received: with LISTAR (v0.128a; list small-list); Sat, 17 Jun 2000 19:43:38 -0400 (EDT)
Date: Sat, 17 Jun 2000 19:43:38 -0400 (EDT)
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small-list Digest Fri, 16 Jun 2000 Volume: 2000 Issue: 090

In This Issue:
Explorer A/C
Re: [Explorer A/C]


Date: Fri, 16 Jun 2000 21:29:27 -0700
From: scott>
Subject: Explorer A/C

My 91 Explorer has lost it's cool and I believe it needs a recharge.
Does the 91 use the older Freon or the newer refrigerent?
If it uses the old Freon is it worthwile to convert to the newer stuff?
Is the conversion something I can do myself?
I do all my own work, but have never touched a A/C system before.


Date: 17 Jun 00 20:32:46 EDT
From: Tim Turner>
Subject: Re: [Explorer A/C]

scott> wrote:

> My 91 Explorer has lost it's cool and I believe it needs a recharge.

More than likely! Nine years would be a long time for the original charge to

> Does the 91 use the older Freon or the newer refrigerent?

R-12 Freon would have been the original gas used.

> If it uses the old Freon is it worthwile to convert to the newer stuff?

That depends on the depth of your pocket Vs. desired A/C performance. Expect
anywhere from equal cooling (with a slower initial cool-down) to 10 Degrees
warmer duct temperatures if you retro-fit to R-134a Suva depending on the
procedures used (and luck!) R-12 is roughly 3-5X the cost of R-134a so
take into account the cost of refilling when the inevitable leak happens.

> Is the conversion something I can do myself?

Yes; but please don't buy one of those damnable 'kits' from the
'mass-merchandisers' without some research first.

> I do all my own work, but have never touched a A/C system before.

I'd suggest posting your question(s) on's BB for more
opinions but here's my suggestions...

1) Be sure the system is in fact empty before ANYthing else; any remaining
R-12 legally must be recovered rather than let into the atmosphere. (I'm sure
a shop would be more than happy to 'steal' your remaining R-12 at little or no
charge assuming it's pure. Expect a charge as they will be testing then
recovering, and recycling it and the equipment involved is not cheap and
requires filter changes etc.)

2) I know certification is required to buy R-12, I believe the law now
requires it for R-134a, but on-line cert's are readily available to
individuals or professionals. (See for a link.)

3) Examine *ALL* the system looking for oily stains at fittings, crimps, seals
etc. If you see it you're seeing a leak that needs repairing before you
refill with whichever gas you choose. (Note.. local laws vary about refilling
a 'known leaking' system.)

4) The dessicant in the drier/acuumulator in a '91 is probably not compatible
with R-134a but if you'll have the sytem open for repair or it's been empty
for more than a few days it needs changing anyway

5) To do it *ALL* yourself then guages and a vacuum pump would be highly
desirable; probably need 'spring-lock' release tools as well to get the
fittings apart unless you have dealer installed A/C.

6) R-134a will not circulate the existing mineral oil properly requiring
either Ester oil (my preference) or PAG oil to be used; both are like brake
fluid in that they absorb moisture and PAG will blister paint AND skin. (wear
gloves if you decide on PAG.. I was OK the first few times I got it on my
hands, but now a trace of it results in small blisters.)

7) Flushing of components is desirable but can also be a road to ruin if any
flush solution is left in the system.

8) Draining the old oil from the compressor is also desirable, but not
mandatory; usually I get very little oil from them.

9) Deep evacuation of the system for at least 45 Minutes is a must to prevent
moisture in the system; moisture + Refrigerant = acid that eats the system
from the inside out.

10) Make sure the fan and fan clutch are in 100% condition (Both are common
faults on the early Explorer.) Make sure the condenser fins are clean as well;
R-134a runs higher pressure on the high side and does not release heat as
effeciently as R-12 so everything must be in tip-top shape for the under-hood
parts of the A/C to cool properly.

11) The cycling switch on the acuumulator will need to be readjusted to
roughly 20 PSI instead of 30 for R-134a use

12) Roughly 85% R-134a to R-12; ie: a 2.5 Lb. R-12 system would use about 2.18
Lb. R-134a with the total oil charge staying the same as R-12 but with
Ester/PAG added.

13) You may wish to do the parts changing yourself and then have a shop do the
evacuation and charging to avoid buying the vacuum pump and guages.

14) There are other gasses besides R-12 & R134a and if you intend to do ALL
your own work they may be of interest to you, but most shops will only service
the two.

15) Every different gas is *supposed* to have it's own unique service fitting
and label color; please adhere to it! You wouldn't believe the mixtures of
gasses I've found in a supposedly pure R-12 or R-134a system before.

Repair all leaks, change the acuumulator, add system capacity of ester oil (6
Oz if unsure), evacuate system and recharge with 80-85% R-134a, adjust cycling

Be warned that R-134a has a smaller molecular structure than R-12 so it *WILL*
leak out quicker than R-12 would and is also harder to detect with electronic
leak detectors.

"Kits" If the system is empty it now has air in it; adding the R-134a & oil
is fine but due to the air the high side pressure will be very high (400 PSI+)
and cooling will be poor at best. If the system is NOT empty and the R-134a
is added you now have a mixture of gasses in the system that no shop (with an
identifier) will service. (Shops without an ID'er will contaminate their
supply if they do.)

I realize this might be confusing; feel free to e-mail me for clarification
and I suggest checking out website as well as the EPA website
concerning mobile air conditioning.

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