If you want to add Freon, you could just wait for the compressor clucth to engage every couple of minutes until the Freon level gets high enough that the Monitor Module keeps the compressor clutch engaged.

Or you can ground the control signal line in the two contact plug going to the compressor which will force the compressor clutch to stay engaged.  Unground the signal line every so often to see how the progress of refilled the Freon is going.  When the Monitor Module keeps the compressor clutch engaged, you are making progress.

Note: you should have the dash and sleeper AC to to maximum.

Even when you have the Freon at the level you want, the Monitor Module LED will still be flashing Red.  To turn off the flasshing Red LED, you turn ignition swich on and off four times in one second intervals.

ACCompressorPlug.pdf