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Topic: a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a (Read 534 times) previous topic - next topic

a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a

My repair guy said he evacuated the system and put in 2# and I should be all set. It was 65 degrees out and we got 55 as a temp out of the dash vent. Seems light to me but he said he put die in and I should come back after I have driven a few hundred miles. We could not find a sticker that told us what the capacity should be and since I am older and smaller than the other post that said 5# of refrigerant was correct, I wondered if anyone knew anything about my system? Thanks in advance

Re: a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a

Reply #1 –
When you switch from a r-12 to 134 use 80% of the factory capacity.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a

Reply #2 –
Usually there is a receiver dryer with a sight glass after the condenser.  If you see bubbles in the glass after the system has run for awhile (15 min or more), it indicates that it is low on refrigerant.  On my coach I have to use a mirror and flashlight to see the sight glass and some have a plug over the glass or may just be too dirty to see anything.  Last week I added a can of 134a and still had some bubbles, but it was cooling very well, so I didn't use another can to add just a few ounces.  Walmart is much cheaper than most auto parts stores, and don't add oil just because you like to oil everything.  The only time to add oil to an AC system is when a major part is replaced or major leak of oil and refrigerant.  Roof AC usually does not have a sight glass or rubber hoses that refrigerant can migrant through like dash air on RV's and other vehicles.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a

Reply #3 –
Can you read the low side pressure? There are charts to show what range of pressure you should have at what temperature
Toby a 94 u280
Cummins 8.3
6 speed Allison
Exhaust brake


Adopted by Derek and Annabelle

Re: a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a

Reply #4 –
I just converted my 1994 U300 to R134a and was expecting to fill with 5 pounds. After 3, 12 ounce cans my sight glass is clear and my low side reading is high. I am going to lower and see if it comes into spec. Also, I read on one sight not to depend on the sight glass for R134a....found that odd. I found the folks at a local ThermoKing very helpful. They matched up a filter-drier and installed a high side fitting with a R134a, 16mm service port. 

Re: a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a

Reply #5 –
Quote from: macjoe –
I just converted my 1994 U300 to R134a and was expecting to fill with 5 pounds. After 3, 12 ounce cans my sight glass is clear and my low side reading is high. I am going to lower and see if it comes into spec. Also, I read on one sight not to depend on the sight glass for R134a....found that odd. I found the folks at a local ThermoKing very helpful. They matched up a filter-drier and installed a high side fitting with a R134a, 16mm service port.
Pressures are different with R134a R-12 operated at a lower pressure. The guide line when I was doing conversions for automobiles was to fill at 80% of the r-12 capacity to get the best temperature at the register. The pressures will still be higher than r-12
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: a/c refrigerant capacity for 30'1992 grand villa that was converted to 134a

Reply #6 –
     I lowered my low side to 35....usually would go to 30. Sight glass is clear. Cooling is good but not like R12. Condenser fans are cycling nicely. Water is pouring out around the vacuum motor next to the evaporator drain...no mud daubers in drain tube.  Will see how it does next week from Boones Mill, Va to Myrtle Beach, SC...5 hours.