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SERVICING
S-26 TESTING TEMPERATURE SENSORS AND EEV COIL
RESISTANCE
The AVZC ComfortNet ready heat pump models are factory
equipped with:
•
(Ta) an outdoor air temperature sensor
•
(Tm) an outdoor coil temperature sensor
•
(TI) an outdoor liquid temperature sensor
•
(Td) a discharge temperature sensor
•
(Tb) a defrost temperature sensor
To check above sensors:
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 power to the heat pump condensor.
2. Disconnect the sensor from the electric board.
3. Connect an ohmmeter across the sensor terminals. The ohm-
meter should read be the resistance shown in the table THER-
MISTOR RESISTANCE AND TEMPERATURE CHARACTERISTICS.
Replace the sensor if the sensor is open, shorted, or outside
the valid resistance range.
Testing EEV coil resistance
To check the resistance of the EEV coil, first disconnect EEV cable
from the PCB board. Make measurements of resistance between
the connector pins, and then make sure the resistance falls in
the range of 40 to 50 .
Outdoor unit: 3. 4. & 5 Ton
Outdoor unit: 2 Ton
S-40A AVPVC HEATER CONTROL
Description
The AVPVC models utilize an electronic control that provides ECM
blower motor control and control of up to two electric heat se-
quencers. The control has thermostat inputs for up to two stages
of cooling, two stages of electric heat, reversing valve, and dehu-
midification. Control input is 24VAC.
All dipswitches necessary to setup cooling and electric heat air-
flow are fully integrated into the control.
Features
The new air handler control includes advanced diagnostic fea-
tures with fault recall, estimated CFM display via on-board LED,
and ComfortNet
TM
ready. Diagnostics includes heater kit selec-
tion diagnostics, open fuse, internal control fault, data errors,
and blower motor faults. Data errors are not included in the
fault recall list. Diagnostic error codes are displayed on a single
red LED.
The estimated CFM is displayed on an on-board green LED. The
LED flashes once for each 100 CFM.
The AVPVC air handlers may be used in a fully communicating
ComfortNet system when matched with a compatible outdoor
unit and the CTK04 thermostat. A fully communicating system
offers advanced setup and diagnostic features.
Basic Operation
The air handler control receives thermostat inputs from the
CTK04 ComfortNet thermostat. The control operates the vari-
able speed blower motor at the demand as determined from the
thermostat input(s). If a demand for electric heat is received, the
control will provide a 24VAC output for up to two electric heat
sequencers.
Troubleshooting
Motor Control Circuits
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. Turn on power to air handler or modular.
WARNING
Line Voltage now present.
2. Check voltage between pins 1 and 4 at the 4-wire motor con-
nector on the control board. Voltage should be between 9
and 15 VDC. Replace control if voltage is not as specified.
Electric Heat Sequencer Outputs
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. Turn on power to air handler or modular blower.
45
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