Checking Fan Relay Contacts; Checking High Pressure Control; Checking Low Pressure Control; Checking Capacitor - Daikin M Series Service And Troubleshooting

SERVICING
Testing Compressor Contactor
(Single Phase)
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.

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:
WARNING
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
(See causes for high head pressure in Service Problem
Analysis Guide). If it cuts out below this pressure range,
replace the control. The control should reset at 420 PSIG ±
25 PSIG.

Checking Low Pressure Control

The low pressure control senses the pressure in the
suction line and will open its contacts on a drop in
pressure. The low pressure control will automatically reset
itself with a rise in pressure.
The low pressure control is designed to cut-out (open) at
approximately 22 PSIG. It will automatically cut-in (close) at
approximately 50 PSIG.
Test for continuity using a VOM and if not as above,
replace the control.
Checking Internal Overload
The Internal Overload prevents the compressor windings
from overheating. Reacts to both current and temperature
Cuts out 302°F. Cuts in between 146 and 176°F
1. Using an ohmmeter, test continuity between
terminals, If either winding test continuous, Internal
overload open.
2. Allow time for the compressor to cool, and overload
to close and retest.

Checking Capacitor

Capacitor, Run
A run capacitor is wired across the auxiliary and main
windings of a single phase permanent split capacitor
motor. The capacitors primary function is to reduce the line
current while greatly improving the torque characteristics
of a motor. This is accomplished by using the 90° phase
relationship between the capacitor current and voltage
in conjunction with the motor windings so that the motor
will give two phase operation when connected to a single
phase circuit. The capacitor also reduces the line current
to the motor by improving the power factor.
WARNING
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