Model: LTD Crown Victoria
Engine Size: 5.0L
Refrigerant Type: R134a
Ambient Temp: 85
Pressure Low: 25-30
Pressure High: 280-350+
Country of Origin: United States
Polling all experts!
I retrofitted my AC system to R134a on my recently acquired box. Performed the following:
-New Delco evaporator
-New Orifice tube
-New rebuilt ac compressor
-Lines flushed with AC flush fluid, condenser also flushed
-HNBR O-rings everywhere
-PAG46 oil added, 3 oz to evap, 1 oz. to condenser, 3 oz.-ish added to compressor (received dried), 1 oz. to receiver/drier; total charge should be around 8 oz.
-Charge R143a to 2 lbs (32 oz.) which is roughly 20% less than the full R12 charge
-Serviced the AC with a Robinair AC machine.
AC blows cold except that I have low suction pressure (20-30 psi) and high discharge (280 psi) at idle. With the engine off idle (1500 RPM), the pressure jumps 35+ on the low side and 350 on the high side. AC remains ice cold. The compressor sounds like it is straining. The receiver/drier gets cold to the touch (almost icy). Does it sound like I have an airflow problem with the condenser?
I'm concerned with the noise. Also, with the fan speed at low, the pressure decreases so low that the low pressure switch kicks the AC compressor off.
Could I have an issue with too much oil?
Mist the condenser with a water hose and see if the high side drops. You may have an airflow problem with not enough air over the condenser. Could be caused by fan clutch.
20-30 psi low side pressure is ideal. The system is designed to cycle off when maximum capacity is not needed (lower ambients or lower fan speed). Your high side is too high though. Is it a fin and tube condenser? Do you have the fan shrouds still in place?
Thanks for the tip. I am running the stock fan shroud with a clutch fan. I will mist the condenser and see how the pressure change. Yes the condenser is tube and fin. Probably going to serpentine style will be better...
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