Install a service pipe on the motor-compressor. And in the service pipe the manifold on the low pressure side.
Test leak at system with pressure of 8kgf / cm or 118 PSI.
Evacuate the system with a vacuum pump for 15 to 30 minutes.
Close the register and check that the pressure gauge indicates from 28 to 30 InHg, if you are indicating this pressure wait a few minutes, the reading should remain stable.
Attach to the manifold by hose an R-22 cylinder, a quick purge to remove air and uncondensable vapors from the hose.
With the system compressor off, inject approximately 130 PSI of refrigerant into the system.
Close the register and turn on the motor compressor the pressure should lower, complete the charge of coolant leaving the pressure in the range of 50 to 70 PSI.
The load will be complete when:
The evaporator is condensing two thirds
The heated condenser
The partially warm system filter
The condensed suction line
The electric current must be in the operating range according to the manufacturer (rated current of the appliance).