SERVICING
43
To check either the outdoor air or outdoor coil temperature
sensors:
WARNING
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 air conditioner or heat pump.
2. Disconnect the sensor from the unitary (UC) control.
3. Connect an ohmmeter across the sensor terminals.
The ohmmeter should read be 10kW, +/-10%, at 75°F.
Replace the sensor if the sensor is open, shorted, or
outside the valid resistance range.
AVPTC/MBVC Heater Control
Description
The ComfortBridge models utilize an electronic control
that provides ECM blower motor control and control
of up to two electric heat sequencers. The control has
thermostat inputs for 2 stages of cooling, and one stage of
electric heat (electric heat staging is done internally), and
dehumidification. Control input is 24VAC. Dehumidification
is enabled/disabled via thermostat.
Features
The new handler control includes advanced diagnostic
features with fault recall and estimated CFM display via
on-board LED. Diagnostics include heater kit selection
diagnostics, open fuse, internal control fault, data errors,
and blower motor faults.
The estimated CFM is displayed on the LED digital display.
ex. A08 = 800 CFM.
The ComfortBridge air handlers may be used in a full
communicating system when matched with a compatible
outdoor system. A fully communicating system offers
advanced setup and diagnostic features.
Basic Operation
The air handler control receives thermostat inputs from a
24VAC thermostat. For cooling and heat pump operation,
the control operates the variable 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
WARNING
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
connector on the control board.
See Electrical Checks -
Low Voltage Control Circuits section.
Electric Heat Sequencer Outputs
WARNING
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.
WARNING
Line voltage now present
2. Disconnect the 4-circuit harness connecting the control
to the electric heater kit.
3. Provide a thermostat demand for low stage auxiliary
heat (W1). Measure the voltage between circuits 1
and 3 at the on-board electric heat connector. Voltage
should measure 24VAC. Replace control if no voltage
is present.
NOTE: Allow for any built-in time delays before making
voltage measurements. Any electric heater faults
that are present may prevent the heater output from
energizing. Verify that no heater faults are present
before making voltage measurements.
Summary of Contents for ASXC16
Page 4: ...PRODUCT IDENTIFICATION 4 ...
Page 5: ...PRODUCT IDENTIFICATION 5 ...
