PUMPDOWN

TM5-4110-234-14

TO 40R7-5-7-1

5-6.

PUMPDOWN (See figures 2-6 and 2-8 or 2-7 and 2-9 for valve identification).

Pumpdown is the operation by which the refrigerant in a charged system is pumped into and maintained within the

receiver. Pumpdown is performed before transportation to a new site and before replacing refrigeration components on

the low pressure side of the system. The refrigerant must be discharged in order to replace the receiver.

a. Check to see that the compressor valves are open (backseated and cracked). To backseat and crack the

service valve you must turn the valve stem fully counterclockwise to backseat and then turn clockwise one turn to "crack."

Figure 5-1. Compressor Service Valves.

Close the defrost hand valve and the receiver outlet valve.

Disconnect power from refrigerator before performing

maintenance on electrical components.

The

voltage used can be lethal.

c. Disconnect power, open control box and adjust the thermostat to a lower setting so that unit will run

continuously. In cases of extreme low temperatures the thermostat can be bypassed by adding a jumper between the two

terminals.

Connect power and move the ON-OFF switch to the ON position.

Serious damage can occur to the equipment if the suction pressure is permitted to drop below 0 psig

during pumpdown. If there is a leak in the system, this will cause air to be drawn into the system through

the leak.

e. Turn the switch to OFF when the suction pressure gage reaches the range of 0 to 2 psig. Do not permit the

pressure to drop below 0 psig.

Observe the suction pressure gage and when pressure increases above 2 psig, turn the unit on again until

the pressure remains in the range of 0 to 2 psig.

5-4