Dash A/C

[scoggins_jim]

--- In WanderlodgeForum@yahoogroups.com, "ejohna2000" wrote:
>
> How much Freon does the dash air take when empty. Both R12 and R 134.
> This is on a 86 PT 38. I was told that you use less R 134 when you
> update an R 12 system. Elmer in Sebring FL.
>
ELMER: Here is what I did.
134A conversion
1986 PT40
Here is some info you all might want to capture.
The air conditioning has gradually deteriorated in my coach. Leaking
R12 into the atmosphere and the expense of replacement R12 drove me
toward a conversion attempt. Factory conversion, while effective, is
expensive ($3500-4000 -- they do replace all the plumbing and all
components -- compressor, dryer, evaporator etc., etc)
After some discussion with my local trusty mech at the Highway Garage,
Stafford, VA, we decided to try a less expensive approach that while
not a perfect solution, gets it done.

Discussion with the factory reps indicate they charged the system with
5-6 lbs. of R12 and then watched the bubbles in the dryer. Note:
watching bubbles is not effective for 134. Accordingly, using the 80%
conversion we figured somewhere between four/five lbs. would be needed.

We installed a new dryer (in passenger overhead--has the sight gage).
The system was evacuated, checked to see if it would hold vacuum, and
filled with 4.5 lbs. of 134A, A/C oil, and leak check dye (while
visible to the eye it is best to use a black light). It was a 90
degree day, sea level-- pressures were 36 and 247 for low/ high side.

So far, so good. While one cannot hang meat it seems to be working fine.

Wouldn't you know it. After completing the evolution, the long time
engineer guru (Guy Moulder) from the factory called. He said the
system was a 6 LB system and I should therefore have 4.8 lbs. of 134A
in the system.

Total expense was a little over $400.

Now I have a base line. I will explore running new and modern plumbing
when/if the need arises.

I bought a charge kit from an auto parts place (about $15) and a
couple of cans of 134A from Wal-Mart. My plan: add no more than 1 can
if things go south on the road somewhere

Here is info I recieved when I was looking for help. Note the
conversion from R12 to R134: 75-80 percent

Quote
The act of conversion fron R12 to 134A can be simple or very
complicated. I have done about 100 conversions both easy and hard. The
easiest way is to go to Wal-Mart and buy the conversion kit for under
$40.00 and do the conversion like the instructions say. I have had
very good success with this method except some Chrysler product with a
block style expansion. The long way around is to have the R12
evaculated by a professional. (this must be done in all cases) remeove
the dryer, and compressor. Flush the system with a conversion flush
(available at NAPA) change all the O rings to 134 type. Replace the
dryer with a 134 type. Drain the compressor of all the oil but DO NOT
FLUSH the compressor. Add 134 oil to the compressor and dryer. Usually
about 8oz.Install the 134 chrage fittings to the low and high pressure
sides. Reassemble and evacuate for at least 90 minutes. Re charge with
R134a. Remember the134 charge weight is 75% to 80% of the R12 charge.
The problem with recharge is 134 is very critical of charge amount.
One oz over and it will increase head pressure a lot. Charge until the
low pressure sidea starts to sweat back and it will work as good or
better than R12. This last method costs between $300/$400. I can
honestly say that both methods work very well as I have done a lot of
both. The cheap kit has an oil additive that neutralizes the R12 oil
and acids. I have seen compressor failures both ways. Fords have more
failure s in the conversions than any. GM's and foreign are easy to
do. I I converted a 90 Honda today and it has 38 degree air. I used
the cheap method. Sorry to ramble but I must say ther are a lot of
untruths out there about conversions but the final decision is up to
you. If I can be of any help let me know. Lee armeter Biloxi, Ms
End quote.

Jim Scoggins
04 M380
formerly
86 PT40 wih a working air conditioner