Carrier 69NT40-541-306, Операция и обслуживание

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T-354 7–46
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 terminals must be checked for voltage with a multimeter.
The discharge resistors installed on the unit (capacitors) should bring the voltage to a safe
level in a minute. However, there may be a broken resistor that retains voltage for a longer
period, it is highly recommended to wait 15 minutes and to check for voltage.
If the capacitors require discharging, first, turn the unit power OFF and disconnect the unit power plug. Then, place
a 20,000 ohm, 2 watt resistor across the terminals of the capacitor for approximately 30 seconds.
The capacitors are located on the unit sidewall above the evaporator fan deck and may be removed by two methods:
• If container is empty - Open upper rear panel of the unit. The capacitors will be on the right and may be
serviced after checking discharge.
• If container is full - Remove the upper fresh air makeup vent.
Checking the capacitor
If the capacitor is suspected of malfunction, you may choose to simply replace it. Direct replacement requires a
capacitor of the same value. Two methods for checking capacitor function are:
1. Volt-ohmmeter set on RX 10,000 ohms.
Connect ohmmeter leads across the 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 back toward a
very high resistance reading. 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 meter probes touch the ter-
minals. 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 value of a capacitor and to detect insulation break-
down under load conditions. The important advantages of an analyzer are its ability to locate capacitors
that have failed to hold their microfarad ratings, or those that are breaking down internally during operation.
It is also useful in identifying capacitors when their microfarad rating marks have become unreadable.