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Table 12—Operating Problems
SYMPTOM POSSIBLE CAUSE
No Display
Thermostat is not receiving power.
1. Verify that comfort zone center is receiving 24 vac. (50 va minimum required with 4 motorized
dampers, 5 va for each additional motorized damper.)
2. Check that the thermostat is receiving a steady 10 VDC across the red and white wires at the
system controller terminal block on the comfort zone, I/O board, and on the Red/White terminals
on the base plate of the 4 zone controller.
Blinking Temperature Display
Low voltage.
1. Verify that the comfort zone center is receiving 24 vac. (50 va minimum required with motorized
dampers, 5 va for each additional motorized damper.)
2. Check that the thermostat is receiving a steady 10 VDC across the red and white wires at the
system controller terminal block on the comfort zone, I/O board, and on the red/white terminals
on the base of the 4 zone controller.
3. Check that the yellow or blue wires are connected properly and not broken at the system control-
ler terminal block on the comfort zone I/O board and on the yellow/blue terminal on the base of
the 4 zone controller.
4. Verify that the terminals are properly installed on the base plate of the controller.
5. Wiring connector block for smart sensor could be defective.
Blinking HEAT or COOL Annunciator
1. Check to see if high/low temperature trip limits have been exceeded.
2. Temperature sensor is improperly wired or defective.
Cooling or Heating is Requested But
The HEAT or COOL Annunciator is
not displayed
1. Must have at least 1 zone with a demand greater than 1.5° F from setpoints.
2. Check system switches. They must be set to AUTO or ON to operate.
3. Have you waited for timeguard (5 minutes) to expire?
COOL or HEAT Annunciator is Lit
But Cool or Heat is Not On
1. Check that the LEDs on the CHR06 relay pack are indicating the correct relay is closed. If not,
check for a bad relay.
2. Measure voltage across common (red) and any de-energized relay. Voltage should be 24 vac.
3. Apply 24 vac directly across relay.
Damper Will Not Open or Close
1. Verify that there are no obstructions binding the damper blade or shaft.
2. Check for 24 vac across common and either the open or close terminals.
3. Check stop switch. If defective, replace actuator.
4. Verify that motor is operating correctly.
5. Check damper fuse.
System is Too Noisy
1. Make sure bypass damper is working properly.
2. Verify that duct work is properly sized.
Unstable Temperature Readings
1. Check for drafts.
2. Use shielded cable.
Room Sensors Fluctuating
1. Make sure that the sensor wire is not run in parallel with any wires carrying AC voltage.
2. Disconnect all other sensors from the comfort zone I/O board and check to see if the sensor
reading is still fluctuating.
3. Disconnect all other sensors from the comfort zone panel and check to see if the problem still
exists.
4. Disconnect the 4 zone controller and re-wire it directly to the I/O board with a separate
5-conductor cable.
5. If all sensors are still fluctuating, replace the 4 zone controller.
6. If only 1 sensor is fluctuating, disconnect that sensor from the I/O board and re-wire it directly to
the I/O board using a separate 2-conductor cable.
7. If the sensor still has the problem, replace the I/O board.
8. Verify if shielded or non-shielded cable is being used.
9. If shielded, follow through the remaining steps. If non-shielded, go to No. 6.
10. Verify that the shield is connected to the comfort zone panel and that the panel is properly
grounded to the chassis.
11. Remove the shield wire and check to see if the problem still exists.
12. Verify that the shield wire has been clipped off at the sensor end and is not touching any other
wires or any exposed metal.
13. Ensure that there is a solid electrical ground on the electric power box.
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