Drain pan is leak proof

Leakage of evaporator coil

Poor insulation at the bottom of drain pan

Worn out shock absorbers on the bus wheels

Chokes the orifice of TEV

Blocks the orifice of AEV

Closes the orifice of TEEV

Closes the orifice of capillary

Moisture in the system

Fully evacuated system

Excess of lubricant in receiver

Non condensables in the system

Defective thermostat

Excessive oil in evaporator

Too close differential in LPC

Defective compressor valve

No refrigerant charge

Shortage of refrigerant

Over charge of refrigerant

Correct charge of refrigerant