I'd suggest using a full manifold gauge set that will allow you to measure high and low side pressures. Use a chart to show pressures vs temperature and fill until you reach proper pressures. Lots more accurate than filling by weight or volume. Your system doesn't hold much more than an auto system.
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Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI
I'd suggest using a full manifold gauge set that will allow you to measure high and low side pressures. Use a chart to show pressures vs temperature and fill until you reach proper pressures. Lots more accurate than filling by weight or volume. Your system doesn't hold much more than an auto system.
Have gauges, just trying to get an idea of how much R134A to have on hand before I start. I won't be buying a large 30 pound can.
There should be a label around the evaporator. By the way, did you evacuate and change drier?
There was no refrigerant in the system when I purchased the unit a few weeks ago. My neighbor put on a new Schrader valve, new drier plus another part, just trying to figure out how much R134A to purchase in advance as it's much cheaper buy on line.
Your auto parts store has a can of freon with oil in it. The can has a hose on it-and a gauge that shows red & green areas. Put somebody in the Coach, put the fan on high, with the A/C on, of Course, add freon till it is cold-then quit adding.
If the Compressor does not kick on-short across the low pressure switch wit a paper clip.
If you want to use your gauges-go for it- but they will just make the program more complicated, and you will have to add an oil/freon can as well
When R-134 became the only legal refrigerant available for automotive use, we converted all our R-12 vehicles. Use a vacuum pump and evacuate the system, add the new oil and add a volume of R-134 to equal 80% of the required R-12 volume. I don't remember the source for the 80% number but I do remember that figure and it did work as advertised.
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'07 Winnebago Journey 34H, ISB-02, MH2500
Toad - '08 Ford Taurus X
Blue Ox, Aventa
US Gear UBS