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Freon capacity for 69 factory air

18K views 7 replies 6 participants last post by  67 Deuce 
#1 ·
I need to know what the freon capacity is for my 69 Nova with factory air. It has a 350 in it if that makes a difference. Does any one know?:confused:
Mine was converted to R34 several years ago but none of the labels showing capacity still exist.
 
#2 ·
It goes by the gauge pressure reading generally. A professional shop might put the freon tank on a scale and charge it by weight if it where a totally dry system totally evacuated and having new parts (dryer in particular). Otherwise the go by the differential between the high and the low gauge readings to determine if it has a full charge.

By the way the hoses from a 1969 car are porous by now and will leak down your system in about a weeks time degrading your cooling performance as the pressure drops.
 
#3 ·
That is good advice Biig Dave. The shop that worked on it evacuated the system pulling .5 lbs. It was done with out running the engine. The recovery system he used enabled him to set the number of pounds to be put back into a fully evacuated system. Then he did as you described watching the gauges on high and low side. He did not know how much to put back into the system. It wound up taking 3.5 lbs of R34 with the system running. He didn't want to but more into it for fear of too much pressure. The site glass was clear as it would be with R12. He said that the site glass in the receiver/dryer could no longer be used to know the condition of the system as we could with R12. He suspected that the expansion valve might need replacement based upon how slowly the high and low side equalized after turning off the ac and that the system did not get to be extremely cold. Back in the days of R12, ice would form on the tube above the expansion value.

Good point about the porous hoses. Thanks.
If the freon capacity is available it would be helpful to know. The NAPA web site had figures but they did not go back to 1969.
 
#4 ·
Who ever worked on your car doesn't know much about refrigeration systems. If you know the system capacity by weight then you charge by weight, how ever any weight capacities listed will be for R-12. R-134 weight will be slightly different. When charging by pressure with R-134 you would charge till the sight glass is full AND discharge pressure is between 125 psi and 150 psi (depending on outside air temp).The suction pressure should be between 25psi and 35 psi depending on load. I am not sure if the Novas use an expansion valve or an orifice tube. They each however have a filter screen to catch trash to prevent them from getting clogged. Given that your car is 43 years old it is a good bet that the evaporator is extrememly dirty reducing cooling capacity. You ststed he pulled vacuum to .5 pounds.... He should have pulled 27.5 plus inches of vacuum (usually you can get 29 plus inches)and held that vacuum for 30 minutes. If it doesn't hold vacuum you have a leak.
 
#6 ·
Greetings from Arizona
when we do conversions we recharge at 80% of orginal freon level using 134. I just redid my 67 Elcamino and my friend did a POA valve redo with POA Valve is drilled out internally and has orfice tube installed internally. It looks stock except extra relay on firewall. He useded r12 to recharge since I stayed with orginal condenser! Jay



 
#7 ·
Its generally about 80% of the original charge. The original r12 charge is around 3lbs 12oz. The sight glass should not show clear. There is a good chance that the expansion valve is not operationg properly or the valve itself. Also to get it cooler you might need to change the condensor assy. to help bring down the temp. There is a company in Florida I believe the name is Classic A/C that has some good parts to convert to 134 and they are reasonable on prices and info is free! They are good people to deal with, I have used them in the past with no concerns.
 
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