AIR CONDITIONING (Cont) - TM-55-1905-223-24-170216

TM 55-1905-223-24-17

Table 4-1. Troubleshooting - CONT

Malfunction

Test or Inspection

Corrective Action

AIR CONDITIONING - CONT

NOTE

The low pressure control solenoid must be bypassed to allow unit to operate below

normal pressure.

(8)

Watch the operating pressure on the combination (suction pressure) gauge.

When pressure has dropped to 2 inches of vacuum on the gauge, stop the

compressor. If the pressure rises rapidly, there is still residual refrigerant in the

compressor. Start compressor and again pump pressure down to 2 inches of

vacuum and stop compressor. If pressure remains at 1 or 2 inches of vacuum,

or rises very slowly, close the compressor discharge (service) valve fully

clockwise.

WARNING

Turn electrical power OFF.

(9)

If pressure remains in a vacuum, secure electrical power to the compressor

and crack the outlet valve from the receiver momentarily to introduce sufficient

refrigerant to obtain only a slight positive pressure of 1-2 psig to prevent air

from being sucked into the system when opened.

WARNING

Do not open system with pressure exceeding 2 psig on the combination (suction

pressure) gauge.

(10) When a slight positive pressure of 1-2 psig is maintained, the liquid line, low

pressure side of the system (including cooling coil/evaporator), and the

compressor can be opened for maintenance and service.

(11) When maintenance is completed, slowly open the refrigerant outlet- valve from

the receiver. Open the discharge (service) valve on the compressor fully

counterclockwise.

(12) Restore electrical power, start and run the air conditioner assembly to check

operation.

4-9