Friedrich V(E, H)A09K25 service manual Method Of Charging, Undercharged Refrigerant Systems

Method Of Charging

The acceptable method for charging the Vert-I-Pak system is the Weighed in Charge Method. The weighed in charge method is applicable to all units. It is the preferred method to use, as it is the most accurate.

The weighed in method should always be used whenever a charge is removed from a unit such as for a leak repair, compressor replacement, or when there is no refrigerant charge left in the unit. To charge by this method, requires the following steps:

1.Install a piercing valve to remove refrigerant from the sealed system. (Piercing valve must be removed from the system before recharging.)

2.Recover Refrigerant in accordance with EPA regulations.

3.Install a process tube to sealed system.

4.Make necessary repairs to system.

5.Evacuate system to 300 microns or less.

6.Weigh in refrigerant with the property quantity of R-22 refrigerant.

7.Start unit, and verify performance.

8.Crimp the process tube and solder the end shut.

NOTE: In order to access the sealed system it will be necessary to install Schrader type fittings to the process tubes on the discharge and suction of the compressor. Proper recovery refrigerant procedures need to be adhered to as outlined in EPA Regulations.

THIS SHOULD ONLY BE ATTEMPTED BY QUALIFIED SERVICE PERSONNEL.

Undercharged Refrigerant Systems

An undercharged system will result in poor performance (low pressures, etc.) in both the heating and cooling cycle.

Whenever you service a unit with an undercharge of refrigerant, always suspect a leak. The leak must be repaired before charging the unit.

To check for an undercharged system, turn the unit on, allow the compressor to run long enough to establish working pressures in the system (15 to 20 minutes).

During the cooling cycle you can listen carefully at the exit of the metering device into the evaporator; an intermittent hissing and gurgling sound indicates a low refrigerant charge. Intermittent frosting and thawing of the evaporator is another indication of a low charge, however, frosting and thawing can also be caused by insufficient air over the evaporator.

Checks for an undercharged system can be made at the compressor . If the compressor seems quieter than normal,

it is an indication of a low refrigerant charge. A check of the amperage drawn by the compressor motor should show a lower reading. (Check the Unit Specification.) After the unit has run 10 to 15 minutes, check the gauge pressures.

Gauges connected to system with an undercharge will have low head pressures and substantially low suction pressures.

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