2003Envoy XL Dual AC 4.2L Weak Cooling

[jsinga]

Hi, thanks for any help...
2003 Envoy XL dual AC manual control 4.2L engine
cooling has grown weak over last year or two.
System has never been opened 245k miles
85 degree outside temp
system would short cycle at any speed above idle
gauge pressures 40psi and 160psi at idle
anything above idle low side would drop to 20psi and compressor cycle off
added 12oz R134a low side still drops to 20psi and cycles off w/engine at 1500 rpm
added about 6oz more R134a low side still pulls down to 20psi and cycles off at anything above 1400rpm also high side pressure up to 225psi
total system charge is 48oz.
Shouldn't the compressor stay on almost all the time?
Vent temps were mid to low 40s after adding refridgerant. Think it also has acuator problems so temps may be off
Should evacuate and charge correct amount before proceeding? A kit with new accumulator orifice, orings and rear TXV is not expensive. should I go ahead and service a system this old before it fails?
Thanks for ideas
JS

[Tim]

Went we had our shop the first thing we would do is remove refrigerant, evacuate, and recharge to spec. You really need to know the correct charge is the system before trying to figure any issues that might be present.

[jsinga]

Thought I'd reply back finally...
I did what Tim suggested. System only had a little over a pound when I evacuated it. Pumped it down for about 15 minutes let it sit for another 10 minutes, and was satisfied it didn't have a serious leak. Once we got the full charge 48oz we ended up with 42 degree vent temp with 89 degrees outside.
We were afraid we had actuator problems since the vents on the drivers side were significantly warmer before recharging. All those gremlins are GONE!
Thanks for the advice.
JS

[GM Tech]

65% of mobile a/c complaints are due to lack of cooling due to loss of refrigerant......put that in your pipe and smoke it!

This is from my 5200 car database....