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How much R134a do I need after total discharge


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I replaced my alternator last week which required me to pull the radiator and air condenser.

After a total discharge, how many cans or ounces will I need to bring my system back, and is there any other maintenance I should do to the system?

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With the system open to atmosphere its a good time to inspect/change the orifice tube. You might want to add some PAG oil (only PAG) if you lost any during the system discharge.

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The system capacity is stated on the label on the accumulator. 2.0 lbs is the specified charge. If you're using 12 oz. cans of R134a, then you will lose 1/2 oz. when you change out the empty cans and bleed the air from the hoses. With that in mind, 3 cans of plain R-134a will be a full charge.

As Ranger said, pull a deep vacuum on the system - I like to let the system vacuum for 45 minutes to 1 hour. The longer, the better. Let the vacuum pump run until the system has 28 inches of vacuum, then close the manifold gage valves and let the system sit for 10 minutes. If the vacuum gage did not drop, the system is probably leak free, start up the vacuum pump, open the manifold gage valves and let the system vacuum for another 45 minutes or so. Then charge the refrigerant into the vacuumed system.

Be sure to replace the o-rings at the connections that were disconnected when the system was opened up. Lubricate the o-rings with mineral oil, not PAG oil as PAG oil is hydroscopic and you do not want moisture near the connections.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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