Haier 2U18MS2VHB Service Manual page 85

Ductless multi-split heat pump, outdoor/indoor, wall mount - highwall, 2'x2' compact cassette, 3'x3' large cassette, slim duct, mid-static ducted, medium static ducted, console
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Test Condensate Pump and Associated Float Switch
If the internal condensate pump does not operate, the pump
may be bad or the float switch may be defective. Perform the
following test:
1. Access the electrical control box.
2. Unplug the float switch from the circuit board.
3. The pump should start.
4. If the pump does not start, check for voltage at the pump
control board connection. There should be 230 Volts AC
to the pump. If there is not, the circuit board is defective.
If there is proper voltage to the pump, either the pump or
associated pump wiring is defective.
Testing Temperature Sensors
The easiest problems to solve will involve codes that are
related to potential failure of temperature sensors. Common
problems may include loose connections, open electrically,
and out of calibration. Checking the condition of the sensors
requires a temperature probe and an ohmmeter.
The Reference Section of this manual contains temperature
resistance tables that can be used to check the calibration
of the sensors. The measured resistance must be within the
tolerances printed on the top of the tables.
1. Confirm the sensor is firmly attached to the circuit board
connection plug.
2. Remove the sensor wires from the connection plug by
releasing holding tension on the plugs tension tab.
3. Use an ohmmeter to test the electrical resistance of the
4. Measure the air temperature near the sensor and compare
the required resistance against measured resistance.
(refer to charts in reference section) If the sensor is
within calibration, the sensor is good. If the sensor is out
of calibration, replace the sensor. (Tube Sensors should
be removed from socket and exposed to air temperature
during test.)

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