Carrier 69NT40-541-001 Operation And Service page 132

b. Removing the capacitor
Make sure power to the unit is OFF and power plug disconnected before removing capacitor(s).
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.
The capacitors are located on the unit sidewall above the evaporator fan deck, and may be removed by
two methods:
a. If container is empty, open upper rear panel of the unit. The capacitors will be on the right and may be
serviced after disconnecting power plug.
b. If container is full, turn the unit power OFF and disconnect power plug. Remove the upper fresh air
makeup vent.
With power OFF discharge the capacitor and disconnect the circuit wiring.
c. 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 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 value of a capacitor and to detect insulation breakdown under
load conditions. The important advantages of a 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
T-316
WARNING
!
WARNING
!
WARNING
!
.
7–44