Compressor not engaging.

[ravenation]

Compressor clutch not engaging.

A/C compressor clutch does not engage. Engages when jumped directly from battery. Gages show 35 pounds on low side.
Can't find, or doesnt have a relay.
Pressure switch...????
Anyone encountered this..???

Sorry, new here. I'll get it down.

1996 ranger extended cab, 2.3 ltr.

 

[bf750]

yes it has a relay and a low pressure switch

 

[Earl43P]

Remove the connector from the cycling switch and jumper its two pins with a paper clip (tape it to prevent short to ground). If the compressor engages, you don't have a relay problem, you are either low on refrigerant or have a bad low pressure (cycling) switch.

You can replace the cycling switch without losing any refrigerant. It has a check valve.
Otherwise, it appears you have a leak.

Look for residual oil at any couplings, with a layer of dirt stuck to it.
Swab the backside of the pulley, shaft seal leaks are very common.

When I service an R-134a system, I stick a thermometer in the center vent, fan on next notch after Low, NOT in Recirc. Run the engine at about 2000 rpm, watching the thermometer drop as refrigerant flows in. As soon as the temperature starts to stop dropping, decerate and shut off the refrigerant flow, noting the temp that you reached.

Drive it 45 mph for at least a mile, watching the thermometer. If it drops lower than it was at 2000 rpm, it is probably as good as you can get it. I have had to let some out to get it colder. There truly is a narrow band of sweet spot with that refrigerant. Your job is to find it, using the thermometer makes it easier.