Checking Contactor Contacts; Checking Fan Relay Contacts; Checking High Pressure Control - Daikin APGM3 Service And Troubleshooting

SERVICING
The compressor contactor and other relay holding coils are
wired into the low or line voltage circuits. When the control
circuit is energized, the coil pulls in the normally open
contacts or opens the normally closed contacts. When the
coil is de-energized, springs return the contacts to their
normal position.
NOTE: Most single phase contactors break only
one side of the line (L1), leaving 115 volts to ground
present at most internal components.
1. Remove the leads from the holding coil.
2. Using an ohmmeter, test across the coil terminals.
If the coil does not test continuous, replace the relay or
contactor.

Checking Contactor Contacts

Single Phase
High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be
present. Failure to do so may cause property
damage, personal injury or death.
1. Disconnect the wire leads from the terminal (T) side of
the contactor.
2. With power ON, energize the contactor.
Line voltage now present.
Testing Compressor Contactor
(Single Phase)
WARNING
WARNING
3. Using a voltmeter, test across terminals.
a. L1 - L2 - No voltage. Check breaker or fuses on
main power supply.
b. T1 to T2 - Meter should read the same as L1 to
L2 in step A. If voltage readings are not the same
as step A, replace contactor.
If a no voltage reading is obtained - replace the contactor.

Checking Fan Relay Contacts

The fan relays are incorporated into the control board. See
Testing Ignition Control Module for checking control board.

Checking High Pressure Control

High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be
present. Failure to do so may cause property
damage, personal injury or death.
The high pressure control senses the pressure in the liquid
line. If abnormally high condensing pressures develop, the
contacts of the control open, breaking the control circuit
before the compressor motor overloads. This control is
automatically reset.
1. Using an ohmmeter, check across terminals of high
pressure control, with wire removed. If not continuous,
the contacts are open.
2. Attach a gauge to the dill valve port on the base valve.
With power ON:
Line voltage now present.
3. Start the system and place a piece of cardboard in
front of the condenser coil, raising the condensing
pressure.
4. Check pressure at which the high pressure control
cuts-out.
If it cuts-out at 660 PSIG ± 10 PSIG, it is operating
normally. If it cuts out below this pressure range, replace
the control. The control should reset at 420 PSIG ± 25
PSIG.
WARNING
WARNING
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