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correct hi and low charging pressures

joeynenj on Tue July 01, 2008 1:08 AM User is offline

Year: 2001
Make: Subaru
Model: outback
Engine Size: 2.5-4cyl
Refrigerant Type: 134a
Ambient Temp: 80
Country of Origin: United States

hi, ok my last post was about the moaning noise coming from the accumulator when the compressor cycles off, everyone suggested i buy a good gauge set, which i finally saved up for a nice mastercool brass set. So now that i have this set how do i know what is the correct hi and low pressures for say 75-80-85 F ambient temp outside for my specific car. I cannot find it anywhere. Also where can i find a chart online that explains the hi and low readings, should i encounter something strange? Thank You

TRB on Tue July 01, 2008 12:54 PM User is offlineView users profile

Compressor Type Zexel DKV-14G 5-Vane
System Oil Capacity 4.0 ozs
Refrigerant (R-134a) Capacity 21-25 ozs.

High Side 399-455 psi (28.0-32.0 kg/cm2 )
Low Side (5) 27-37 psi (1.95-2.60 kg/cm2 )


When considering your next auto A/C purchase, please consider the site that supports you:

bearing01 on Tue July 01, 2008 1:20 PM User is offline

The title of your thread asks for charging pressures. Don't use pressures to charge the system. Pressures can be all over the place for several reasons such as humidity or air temperature. They are good rules of thumb to sanity check the system but you can have significantly different charge levels in the system and still get the correct ball park pressures. When charging you always go by refrigerant weight. If you don't have a scale then you can ball park it by number of R134a can's. There's 12 oz weight in a can and use appropriate number of cans. For the last can, if you only need part of it, you could try to guess the remaining amount of liquid in it by quickly turning it on its side until the tap (or valve) starts to suck in liquid. The gauge pressure should dip when you suck in the liquid. That lets you know where the liquid level in the can is.

Also don't forget to account for weight of refrigerant in the manifold gauge lines.

If you are charging your system then the next tool to invest in is a Mastercool Vacuum pump.

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