1998 S10 Blazer 2-door 4x4 4.3 V6 Automatic transmission.

My ac isn't blowing cold. The compressor is cycling every 2 or 3 seconds. I hooked it up to the manifold gauge but I'm not sure what my readings mean. It seems that when the compressor kicks on both my high and low are raising.
https://youtu.be/x0B3N_CfSos

 

Low side pressure is cycling between 70psi & 58psi which would put the dash outlet temperature around 64 degrees, unacceptable. The compressor should come on at 42psi, and shut off at 22psi. The clutch cycling switch is what controls the low side pressure. Start by replacing the clutch cycling switch on the accumulator. No need to discharge the system. Unplug the electrical connector, and unscrew the switch. Make sure the green O ring is on the accumulator fitting, and screw the new switch on, hand tighten only, no wrenches. Factory Air System Mounted Cycling Pressure Switch 36659: Advance Auto Parts


High side pressure should come up after the cycling switch is replaced, however, depending on your ambient temperature, the system may be low on refrigerant. Connect the manifold set and post another Youtube. There is no way to know what the state of charge is in a CCOT system. If it's low on charge, the system MUST be drained, evacuated, and recharged with the proper amount of R134a.

 

Replaced Low Pressure switch, outside temp is 81 degrees F. Still no cooling, and compressor is still cycling fast.

 

Low side is high, and high side is low, they are indicating the same pressure as the gauges sweep. One of two things: either the system is low on refrigerant, (paragraph 2 in post #2) and needs to be drained, evacuated, and recharged, or the compressor is bad. This type of HVAC system MUST be evacuated to 29.4" hg for a minimum of one hour before recharging.

 

Thank you. I will take it in to be drained and charged. If that doesn't work I will have them change the compressor.

 

Shouldn't have to tell them to evacuate it, they should know