How much Freon?

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How much Freon?

Postby OldsStarfire » Thu Jul 14, 2016 10:18 am

I'm having my stock AC system recharged on this 77 Starfire. Does anyone know how much Freon / R134a it takes? I'm not home so I can't look it up in the manual.
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Re: How much Freon?

Postby stage169 » Thu Jul 14, 2016 12:11 pm

I checked the 77 shop manual and it shows performance data for the Monza with a refrigerant charge of 3lbs minus 8 Oz.

Why they didn't just say 2.5 lbs I'm not sure but there is another performance data listing just for the Vega and its charge is 3lbs.

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Re: How much Freon?

Postby classic_cruiser » Thu Jul 14, 2016 1:34 pm

Are you charging the stock system with R12 or R134? The charge in the manual is for R12; R134 is usually 65-80% of the R12 charge when retrofitting.
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Re: How much Freon?

Postby monzaaddict » Thu Jul 14, 2016 1:54 pm

The cooling will not be as good with r134 vs r12. Despite what you hear about the cost of r12 there is little demand and cans can be found on craigslist fairly cheap.
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Re: How much Freon?

Postby OldsStarfire » Thu Jul 14, 2016 4:40 pm

Thanks guys!
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Re: How much Freon?

Postby rpoz-29 » Thu Jul 14, 2016 7:34 pm

Be careful. I switched from R12 to 134 on an old Ford truck. I used the same amount of 134 as I would have R12. It did not cool very well. I asked around, and was told the 65-80% ratio. I released some of the 134, it worked fine.
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Re: How much Freon?

Postby MonzaRacer » Sun Aug 28, 2016 1:49 am

Actually the old rule was to charge to 80%. BUT remember to flush the system and use ester 100 oil unless its ALL new parts. Remember to ugrade the desicant to XH7.
If your using the A6 compressor it holds 11 oz oil alone, figure 1.5 oz for condenser and evaporator and add 1-3 for rest of system.
The appropriate way to recharge when converting is to make sure the system control is operable and proper. If the system has a thermostatic expansion valve your good to go if its functional. If your using an orifice tube you need to upgrade to a R134A GM Automatic adjusting orifice tube.
IF it is a CCOT(converted to AAOT) you will most likely need to find and install an adjustable cycling switch on the low side.
Most R134A operating pressures on CCOT/AAOT system low side should be around 28-32 psi with idle step up solenoid or idle up control built into the computer, then run it up around 1500-2000 and watch the pressures. I prefer to get the fan clutch(use a thermostatic one) or electric fan on while AC is on.
Watch your high side pressures, try to get enough air flow to keep high side in the 250 psi range on a warm day lower on cooler days. If you cant get low high side pressure you may need better condenser or add on condenser to up capacity.
Now what your looking for in temps a 30 degree drop from center outlet with max ac on and fan on high. Now get a decent infrared temp gauge and check inlet and outlet temps of the condenser you should be getting a 40 degree split from inlet to outlet or its too small condenser or too low of air flow.
I tend to up grade parts to newer controls and rework the hoses and such.
A good wrecking yard should allow you to pick over condensers from newer cars or if possible actually pull one with hoses from a car.
I have helped convert many cars to R134A by substituting newer systems.
As for the A6 compressor there is a company making a Nippondenso variant that bolts in place of older A6 compressors.
I love A6s as I have used them for air compressors in air ride systems before, the biggest issue is if it cycles a lot it wears out fast.
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Re: How much Freon?

Postby RedFiveKBS » Tue Aug 30, 2016 12:25 pm

Just recharged mine yesterday with R12.

r12.jpg

Thankfully, my brother is an HVAC guy and has a stash of R12. :D Actually got a little colder than the 39.7 on the thermometer but not much. Hopefully it holds the charge. Didn't hear or see any leaks.
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