Method Of Charging; Undercharged Refrigerant Systems - Friedrich H)A09K25L Service Manual

Method Of Charging / Repairs
The acceptable method for charging the RAC 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
sealedsystem. (Piercing valve must be removed from the
system before recharging.)
2. Recover Refrigerant in accordance with EPA regulations.
BURN HAZARD
Proper safety procedures must be followed,
and proper protective clothing must be worn
when working with a torch.
Failure to follow these procedures could
result in moderate or serious injury.
3. Install a process tube to sealed system.
ELECTRIC SHOCK HAZARD
Turn off electric power before service or
installation.
Extreme care must be used, if it becomes
necessary to work on equipment with power
applied.
Failure to do so could result in serious injury or
death.
HIGH PRESSURE HAZARD
Sealed Refrigeration System contains refrigerant
and oil under high pressure.
Proper safety procedures must be followed,
and proper protective clothing must be worn
when working with refrigerants.
Failure to follow these procedures could
result in serious injury or death.
22
WARNING
WARNING
WARNING
CAUTION
FREEZE HAZARD
Proper safety procedures must be followed,
and proper protective clothing must be worn
when working with liquid refrigerant.
Failure to follow these procedures could
result in minor to moderate injury.
4. Make necessary repairs to system.
5. Evacuate system to 200 microns or less.
6. Weigh in refrigerant with the property quantity of R-410A
refrigerant.
7. Start unit, and verify performance.
WARNING
BURN HAZARD
Proper safety procedures must be followed,
and proper protective clothing must be worn
when working with a torch.
Failure to follow these procedures could
result in moderate or serious injury.
8. Crimp the process tube and solder the end shut.

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.)