Want to know operating pressures on a 134a refrigerator low and high

Refrigerant HFC-134a or R134a
Weight 330 - 390 gms
With correct refrigerant:
Low side pressure 1.5-2.5 kg/cm2
High side pressure 14-16 kg/cm2

start with checking a/c pressures is compressor cycling? does it have electric cooling fan? it should come on with a/c. usually there is a low limit/high limit switch. if pressure is low, say below 22psi @ low side port, switch will cut compressor. A quick electric "jump" of low limit switch will confirm clutch,compressor operation,but if pressure is low you may want to add freon. know your a/c system r-12 or r-134a,iv'e found converting to r-134a cheaper than purchasing r-12. r-134a takes a special pag oil and should not be used/mixed with ester oils. i could say more on subject but that's a start,of course always wear safety glasses and approach high side port with caution,which most newer cars don't have. thanks

On hot day @ 85=+ degrees it should be between 45 to 50 pounds on the low side pressure port

Good day,
The low side (suction pressure) is pretty nominal at 2 to 4 lbs.
The high side should range from 120 to about 14 lbs. depending on load and ambient temperature.
This would be after 15 minutes running time. Doors closed. Rear panel on as well as can be attached with gauge hoses protruding.

low side 0 to 3 lbs
high side 90 to 125 lbs

the temp matters

YOU NEED 28 PSI ON LOW SIDE AND ABOUT 190 ON HIGH SIDE.YOUR REFRIGERANT IS LOW THAT WHY COMPRESSOR CYCLING ON AND OFF.

No,you won't find it in the owner's manual. It charges through the low pressure side,which is the larger of the 2 available ports. You can't hook it up wrong. I suggest you buy a Hayne's manual for the truck. It has 90% of any answer you might need. A/C can be tricky to fix for the novice. If charging doesn't work,take it to the shop.

I would go for 40 on the suction and 150 discharge, or divide the locked rotor current by 6 and charge so the current is 1/6 of the locked rotor current of the compressor, or by temperature/pressure relation 110* discharge and 35* suction, or get the suction line sweating. The best way is to remove all the refrigerant and then weigh the refrigerant the system is designed for on these critical charge appliances.

You need to replace the condensor, then take it to a shop to have the a/c system evacuated and recharged to purge moisture because the system was opened. That will cost around $150. You do not need to replace the receiver/dryer/suction accumulator even though they will tell you that you do.
go to car-part.com to find prices of condensor from salvage yards. Page with asterisk on it is the lowest priced part.

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The Refrigerant Cycle
During stabilized conditions (air conditioning system shutdown), the refrigerant is in a vaporized state and pressures are equal throughout the system. When the A/C compressor (19703) is in operation it increases pressure on the refrigerant vapor, raising its temperature. The high-pressure and high-temperature vapor is then released into the top of the A/C condenser core (19712).
The A/C condenser core, being close to ambient temperature, causes the refrigerant vapor to condense into a liquid when heat is removed from the refrigerant by ambient air passing over the fins and tubing. The now liquid refrigerant, still at high pressure, exits from the bottom of the A/C condenser core and enters the inlet side of the A/C evaporator core orifice (19D990).
The A/C evaporator core orifice is the restriction in the refrigerant system that creates the high pressure buildup in the A/C evaporator core (19860) and separates the high and low pressure sides of the A/C system. As the liquid refrigerant leaves this restriction, its pressure and boiling point are reduced.
The liquid refrigerant is now at its lowest pressure and temperature. As it passes through the A/C evaporator core, it absorbs heat from the passenger compartment airflow passing over the plate/fin sections of the A/C evaporator core. This addition of heat causes the refrigerant to boil (convert to gas). The now cooler passenger compartment air can no longer support the same humidity level of the warmer air and this excess moisture condenses on the exterior of the evaporator coils and fins and drains outside the vehicle.
The suction accumulator/drier (19C836) is designed to remove moisture from the refrigerant and to prevent any liquid refrigerant that may not have been vaporized in the A/C evaporator core from reaching the A/C compressor. The A/C compressor is designed to pump refrigerant vapor only, as liquid refrigerant will not compress and can damage the A/C compressor.
The refrigerant cycle is now repeated with the A/C compressor again increasing the pressure and temperature of the refrigerant.
The A/C cycling switch (19E561) interrupts compressor operation before the external temperature of the A/C evaporator core gets low enough to cause the condensed water vapor (excess humidity) to turn to ice. It does this by monitoring low side line pressure. It is known that a refrigerant pressure of approximately 210 kPa (30 psi) will yield an operating temperature of 0°C (32°F). The A/C cycling switch controls system operation in an effort to maintain this temperature.
The high side line pressure is also monitored so that A/C compressor operation can be interrupted if system pressure becomes too high.
The A/C compressor pressure relief valve (19D644) will open and vent refrigerant to relieve unusually high system pressure.
Clutch Cycling Orifice Tube Type Refrigerant System
Item Part Number Description 1 19E762 A/C charge valve port (low side) 2 19E561 A/C cycling switch 3 19C836 Suction accumulator/drier 4 19703 A/C compressor 5 19D644 A/C compressor pressure relief valve 6 19D594 A/C pressure cut-off switch 7 19E762 A/C charge valve port (high side) 8 19712 A/C condenser core 9 19D990 A/C evaporator core orifice 10 19860 A/C evaporator core 11 — Low pressure vapor 12 — High pressure vapor 13 — Low pressure liquid 14 — High pressure liquid

1. Connect the R-134a A/C Refrigerant Center to the low- and high-pressure service gauge port valves.
2. Evacuate the system until the low-pressure gauge reads at least 99.4 kPa (29.5 in-Hg) (vacuum) and as close as 101.1 kPa (30 in-Hg) as possible. Continue to operate the vacuum pump for a minimum of 45 minutes.
3. Turn off the evacuation pump. Observe the low-pressure gauge for five minutes to make sure that the system vacuum is held. If vacuum is not held for five minutes, leak-test the system, service the leaks, and evacuate the system again.
4. Correctly oil match the system to verify that the correct amount of refrigerant oil is present in the system. For additional information, refer to Refrigerant Oil Adding in this section.
5. Charge the system with the specified weight of refrigerant and refrigerant oil.
6. When no more refrigerant is being drawn into the system, start the engine and select MAX A/C operation. Set the blower motor speed to maximum and allow the remaining refrigerant to be drawn into the system. Continue to add refrigerant into the system until the specified weight of R-134a has been added. Close the charging cylinder valve and allow the system to pull any remaining refrigerant from the hose. When the suction pressure drops to approximately 207 kPa (30 psi), close the charging hose valve.

Some of this TRUE don't have service valves, but you can put a tapping valve (A1) in the appendix (small piece of pipe comming out of the compresor and seal on the other end).To check the pressure you need to know what type of refrigerant is in the system .If is 134a the low side should be about 24psi and the high around 160 it could vary depends how hot is inside the place and the fridge but not much more than 200.If you working with R22 pressures be around 60 low and 250 high side.