Penguin A/C No Start

I recently purchased a 1994 Excella 34' that had been sitting for over 4 years unused. The penguin a/c unit will run the fan only when in the cool position. I have taken the cover off (which was broken in several places) and blown everything out. Have taken the cover off of the capacitor and electronic board compartment and the capacitors and the board look good. Can hear no clicking from the thermostat on the unit when trying to get compressor started. Voltage is good, and plugged into a dedicated 30 amp circuit. Is there a pressure switch that would prevent the compressor from starting if the refrigerant is low? Any ideas on why no compressor start. I have gone back through the forums 5 years but not found any relevant information. Thank you.