Control Board; Electronic Expansion Valve; Relay In Eev Control Box; Stator Coil - Bard Q36A4DA Installation Instructions Manual

Control Board

Check that the controller is getting 24VAC signal
(GO 24VAC Hot and G 24VAC common). Reference
unit wiring diagram for proper connections. If 24V
is present but the green LED is not lit, replace the
controller. If the green LED is now lit but the superheat
is still not being maintained, troubleshoot the relay to
check that the DI is connected to G; refer to Relay in
EEV Control Box.

Electronic Expansion Valve

Check to see if valve can be moved by manually moving
the stepper motor using the EEV service tool shown
in Figure 31 (Bard Part # 2151-021). If valve still
does not control, check the transducer and thermistor
sensors as described on page 43. If sensors are good,
replace the valve.

Relay in EEV Control Box

Contacts NO to DI and COM to G must be closed for
EEV control to start controlling superheat. Check that
the relay is getting 24VAC. Reference unit wiring
diagram for proper connections. If 24V is present,
measure the resistance between COM and NO; it
should be 0 ohms when the relay is getting 24V. If the
resistance is out of range, replace the relay.

Stator Coil

Disconnect the stator from the valve and the control
and measure the resistance of the windings using an
electrical tester. The resistance of both windings should
be around 40 ohms +/– 10%. The four wire sets that
will have resistance between them are: White and red,
green and red, yellow and purple, blue and purple. If
the resistance falls outside these values, replace the
stator.

Transducer Sensor

1. Check continuity of all three wires from transducer
plug to controller plug. Replace wires if poor
connection in any wire.
2. Check to ensure wires are correctly connected as
follows:
Blue wire = pin 1 of controller plug to pin C on
transducer plug
Red wire = pin 2 of controller plug to pin B on
transducer plug
Black wire = pin 3 of controller plug to pin A on
transducer plug
3. Check that there is 5VDC Nominal between the red
and black wires going to the transducer.
4. Check the signal voltage between the blue and
black wires (0.5-4.5VDC Actual). The following
formula and Figure 32 can be used to determine if
the transducer's voltage to pressure ratio is within
range. Replace transducer if out of range.
Formula for Tech:
(Measured Pressure x .016) + .5 =
Expected Transducer Signal Voltage (see Figure 33).
FIGURE 33
Voltage to Pressure: Suction Pressure Transducer
Manual 2100-752B
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