Service manual

6-28T-294-01
6.26 POWER FACTOR CORRECTOR
CAPACITORS (PFC)
The power factor corrector capacitors are of the
permanent-splitcapacitortype.Thereareatotalof three
capacitors with discharge resistors enclosed in a single
case.
a. When to check for a defective capacitor
The capacitors assist in correcting current draw by the
compressor. If one or more of the capacitors is faulty,
there will be an imbalance in current. In addition, the
power consumption of the unit will increase.
b. Removing the capacitor
WARNING
Make sure power to the unit is OFF and
power plug disconnected before removing
capacitor(s).
WARNING
Before removing the capacitors the
terminalsmustbecheckedforvoltagewitha
multimeter. The discharge resistors
installed on the unit (capacitors) should
bring the voltage to a safe level in a minu te.
However, there may be a broken resistor
that retains voltage for a longer period, it is
highlyrecommended towait15minutes and
to check for voltage.
1. The capacitors are located on the unit sidewall
abovetheevaporatorfandeck,and mayberemoved
by two methods:
(a.) If container is empty, open upper rear panel of
theunit.Thecapacitors willbeontherightand
may be serviced after disconnecting power
plug.
(b.)Ifcontainerisfull,turntheunitpowerOFFand
disconnectpowerplug.Removetheupperfresh
air makeup vent (see Figure 2-1).
WARNING
With power OFF discharge the capacitor
and disconnect the circuit wiring.
c. Checking the capacitor
If the capacitor is suspected of malfunction, you may
choosetosimplyreplaceit.Directreplacementrequires
a capacitor of the same value. Two methods for
checking capacitor function are:
1. Volt-ohmmeter set on RX 10,000 ohms.
Connect ohmmeterleads acrossthe capacitor terminals
and observe the meter needle. If the capacitor is good,
the needle will make a rapid swing toward zero
resistance and then gradually swing backtoward avery
high resistancereading. The reading should read about
330,000 ohms (for a good capacitor) due to the
discharge resistors.
If the capacitor has failed open, the ohmmeter needle
will not move when the m eter probes touch the
terminals. If the capacitor is shorted, the needle will
swing to zero resistance position and stay there.
2. Capacitor analyzer:
The function of the analyzer is to read the microfarad
valueof acapacitorand todetect insulationbreakdown
under load conditions. The important advantages of a
analyzer are its ability to locate capacitors that have
failed to hold their m i crofarad ratings, or those thatare
breaking down i nternally during operation. It is also
useful in identifying capacitors when their microfarad
rating marks have become unreadable.
6.27 CONTROLLER/DATACORDER
a. Handling of Controller/DataCORDER
Theseguidelinesshouldbefollowedwhenhandlingthe
Controller/DataCORDER module. These steps should
be implemented when replacing the module, when
doinganyarcweldingontheunit,orwhenservicetothe
refrigerationunitrequireshandlingandremovalofthe
Controller.
CAUTION
Remove Controller/DataCORDER module
and unplug all connectors before
performing any arc welding on any part of
the container.
Do notremove wireharnessesfrommodules
unless you are grounded to the unit frame
with a static safe wrist strap.
1. Obtain a grounding wrist strap and a static
dissipation mat. The wrist strap, when properly
grounded, will dissipate any potential buildup on
the body. The dissipation mat will provide a
static-free work surface on which to place and/or
service the Controller/DataCORDER module.
NOTE
Use a dissipation mat, order CTD P/N
07-00277-00.
2. Disconnect and secure power to the unit.