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The Electronic Expansion Valve (EEV) installed in this heat pump is designed to control
superheat entering the compressor when the system is running in mechanical heating mode.
During cooling mode, refrigerant flow bypasses the EEV via a check valve and is controlled
by the expansion device in the indoor unit. Therefore, any operational problems
observed in cooling mode are not caused by the EEV.
The following flow chart was designed to assist in troubleshooting the EEV.
Note: The EEV closes with every OFF cycle in the heating mode of operation. During
Defrost and in the cool
sound can be heard when valve is changing positions.
System is pumping down
in heat mode
Low superheat (flooding) in
heating mode
High superheat (low
suction pressure) in
heating mode
EEV Hunting
(Suction pressure moves
up & down)
TROubLeSHOOTING THe eeV
ing mode of operation, the EEV will drive to 1/2 open. An audible
EEV is not sensing that the compressor is
ON and in the Heat Mode
1. Check plug and harness to J6
2. Verify 24VAC at Y1 and/or Y2 inputs to
EEV control J6 are present (not "O") See
Table 6 in Service Facts.
EEV valve is stuck open
1. See Service Facts for Close Valve Test
System is low on charge
1. Check charge per Service Facts
Sensor are out of calibration
1. Verify sensors are accurate. See Table 7
& 8 in Service Facts
System is very low on charge
1. Check charge per Service Facts
EEV valve is stuck closed
1. See Service Facts for Open Valve Test
Sensors are out of calibration
1. Verify sensors are accurate. See Table 7
& 8 in Service Facts
Sensors are out of calibration
1. Verify sensors are accurate. See Table 7
& 8 in Service Facts
EEV valve is stuck closed
1. See Service Facts for Open Valve Test
Verify temperature sensor is clipped tight
to suction line and insulated
Verify Outdoor Unit:
1. Is free and clear of ice and debris
2. Has adequate clearance
3. Distributor tubes are not bent or kinked
13
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