Author:
Jim Scoggins
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Date Posted: 11/ 7/ 01, 3:34am
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
Hope this helps. Contact me if you need more info. I saw where some one said i did this my self. Sorta true. I did the dirty work but paid an air conditioner tech for his brains and the evacuation and gage work. Any automotive air conditioner guy can do this.
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A/C - "AutoFrost" ... an alternative to R12?