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SERVICING
S-40A AVPEC HEATER CONTROL
Description
The AVPEC 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 variable stage of
cooling/heating, two stages of electric heat, reversing valve, and
dehumidification. Control input is 24 VAC.
Features
The new air handler control includes advanced diagnostic fea-
tures with fault recall, estimated CFM display via on-board 7
segment display, and ComfortNet
TM
ready. Diagnostics includes
heater kit selection diagnostics, open fuse, internal control fault,
data errors, and blower motor faults. Data errors are not in-
cluded in the fault recall list. Diagnostic error codes are dis-
played on a single red LED.
The estimated CFM is displayed on an on-board 7 segment display.
For example, if the CFM is 1240CFM, 7 segment display shows
"FC...A...12...40...".
The AVPEC 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 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
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!
To avoid personal injury or death due to
electrical shock, disconnect electrical
power before performing any service
or maintenance.
1. Turn on power to air handler or modular blower.
WARNING
Line Voltage now present.
2. Disconnect the 3-circuit harness connecting the control to the
electric heater kit.
3. Provide a thermostat demand for low stage auxiliary heat .
Measure the voltage between pins 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 measure-
ments.
Communications (Applies only to Systems with Compatible
ComfortNet
TM
Outdoor Unit and CTK04**Thermostat)
The integrated air handler control has some on-board tools that
may be used to troubleshoot the network. These tools are: red
communications LED, green receive (Rx) LED, and learn button.
These are described below
a. Red communications LED – Indicates the status of the network.
Refer to the Network Troubleshooting Chart for the LED status
and the corresponding potential problem.
b. Green receive LED – Indicates network traffic. Refer to the
Network Troubleshooting Chart for the LED status and the cor-
responding potential problem.
c. Learn button – Used to reset the network. Depress the button
for approximately 2 seconds to reset the network.
Voltages between the two data lines and between each data line
and common may be used to determine if the network is operat-
ing properly.
Do the following to measure the voltages on the communications
data lines.
WARNING
Line Voltage now present.
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