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#1
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Correct R134a Pressure at 2k RPMS???
I just checked the low side pressure on my Father in Law's 2004 Buick LeSabre (R134). It read 62PSI when reved and held at 2000 RPMs. The ambient temperature is approx. 105F here today. At idle he was about 10-15PSI higher than that. His A/C was recently charged by the dealership.
I just converted my w124 300d to 134a and I'm at around 40-45PSI at 2k RPMs. Is this right for the ambient temp of 105F? Will it hurt to go higher (i.e. 62 PSI like my father in law's Buick)? I noticed that my compressor clicks on and off pretty quickly if I go higher than 45PSI. I'm not at all an A/C pro. I took the car to a shop to have the system pulled with a vacuum for 45 minutes before charging. I converted to 134a last year when changing the compressor. Just looking for a few tips before we head out on an 8 hour trip. Cold air would be nice! Last, has anyone compared Freeze 12 to plain old 134a?
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-E300d '99 350k -Suburban '93 220k -TDI Jetta '03 350k Sold -F250 '96 7.3 -Dodge Ram 12V -E320 '95 200k -E320 Wagon 1994 155k -300d Turbo '87 187k miles -E320 1994 200k -300d Turbo '84 245k (sold to Dan62) -300d Turbo '84 180k -300sd '80 300k -7.3 Powerstroke Diesel 15P Van 500k+ miles -190d '89 Non Turbo 2.5 5cyl 240k (my first MB) Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's. |
#2
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I'm no A/C guru so hopefully some more experienced members will chime in. What your low side pressure is indicating, is the pressure of the refrigerant by the evaporator. If you know the pressure of refrigerant, you know its corresponding temperature simply by looking at the pressure/temperature chart for that refrigerant. That is what the pressure is telling you, not the amount of refrigerant in a system.
Ideally, you'd like a low side pressure of about 27psi with R-134 at the evaporator. That means your evaporator temp will be slightly above freezing. The hotter it is outside, however, the harder it is for heat transfer to take place so your low side pressures will generally be higher as outside air temperatures increase. Remember, a 30 pound container of refrigerant will show the same pressure at any given temperature whether it has 30 lbs of refrigerant in it or just 1 pound. The same is basically true for your car. A/C work can be complicated and dangerous. Its best to leave it to a professional unless you really take the time to learn. Good luck. Scott
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Scott 1982 Mercedes 240D, 4 speed, 275,000 1988 Porsche 944 Turbo S (70,000) 1987 Porsche 911 Coupe 109,000 (sold) 1998 Mercedes E300 TurboDiesel 147,000 (sold) 1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!) 1997 Mercedes E300 Diesel 236,000 (sold) 1995 Ducati 900SS (sold) 1987 VW Jetta GLI 157,000 (sold) 1986 Camaro 125,000 (sold - P.O.S.) 1977 Corvette L82 125,000 (sold) 1965 Pontiac GTO 15,000 restored (sold) |
#3
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ACkits has a temp/pressure chart. Freeze-12 cools better the R134. R12 cools the best.
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RRGrassi 70's Southern Pacific #5608 Fairmont A-4 MOW car 13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete. 91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K 90 Dodge D250 5.9 Cummins/5 speed. 400K |
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