Programmable Zone Sensor
BAYSENS119* and
BAYSENS019C (Obsolete)
For programming information, refer to literature ACC-SVN28*-EN. This Literature can be obtained at your local Trane Parts Center.
Testing the Programmable Zone Sensor (PZS)
1. Verify unit operation by running unit through test mode.
2. Verify that the PZS has a normal display of time, temperature, fan and system status.
3. For UCP Micro, disconnect wires from LTB-11 (-) and LTB-12 (+); For ReliaTel controls, disconnect wires from J6-11 and J6-12. Measure the dc voltage between terminals 11 and 12. Voltage should read
between 28 to 32 VDC. If no voltage is present for UCP micro, check wiring between UCP and LTB.
4. Reconnect wires to terminals 11 and 12. Measure the voltage between 11 and 12 again. Voltage
should flash at 0.5 second rate, with a voltage value randomly changing from approximately 24 to 32
VDC.
5. On the PZS, press the FAN button to turn the fan ON. If the fan comes on, the PZS is good; if the fan
does not come on, the PZS may be defective and will need to be replaced.
Note: The sensor will not communicate if the wrong baud rate is selected. The PZS is shipped with the baud rate set to 1200. See option menu setup in the literature to verify proper baud rate. The baud rate may need to be changed to 1024 for units built before 1/96.
Troubleshooting the Programmable Zone Sensor
Because the PZS is a communicating sensor, troubleshooting is very limited. Step 2 through Step 5
of testing the sensor are the first steps to verify. The following table will provide other troubleshooting tips for diagnosing the sensor and unit operations.
If all wiring and preliminary tests do not indicate any defects, disconnect the PZS from the wall and take to the unit, and with a short (approx. two feet) length of thermostat wire, connect the PZS and see if symptoms still exist. If not, check for thermostat wire routing in close proximity of high voltage wires and fluorescent lights.
Table 1. Troubleshooting Matrix
| Symptom | Probable Cause and Solution |
| Display does not come on. | Check for 24VAC on terminals 11 and 12 of the sensor. |
| No communication with the unit. | Verify a varying voltage per step 2 of "Testing the Sensor". If no voltage is present, check the wiring between the PZS and the unit. |
| Sensor is communicating, but the unit won't run. | Check Option 18 in the "Options Menu" setup for the correct baud rate. |
| Displayed zone temperature is different from the actual temperature. | Follow the "Option Menu" in the literature to calibrate the display. |
| Zone Temperature is no displayed. | Check option selection in the "Options Menu" setup. |
| Displayed zone temperature reads "99". | Space temperature is above or below the measurable range of the sensor. |
| Displayed zone temperature reads "Sh" and the "COOL FAIL" icon is illuminated. | Verify that option 11 in the "Option Menu" is set correctly. If correct, check wiring from remote sensor at terminals S1 and S2 for a "short" condition. |
| Displayed zone temperature reads "oP" and the "COOL FAIL" icon is illuminated. | Verify that option 11 in the "Option Menu" is set correctly. If correct, check wiring from remote sensor at terminals S1 and S2 for an "open circuit" condition. |
| Programmable sensor will not respond to keypad selections. | Check the lower left corner of the display for a "Padlock" icon. If displayed, press and hold the "Time +" and Time -" keys simultaneously until the icon goes away. |
| Fan mode is set to on, but does not run during unoccupied mode. | Check option 6 in the "Option Menu" setup for "Auto" selection during unoccupied mode. |
| Buzzer indicates "System Failure". Check filter or service is required. | Press erase key to reset filter lapse timer. Buzzer will be reset until noon of the next day if a system failure has not been corrected. |
| Sensor will not hold override changes. | Press "HOLDTEMP" button within 20 seconds after changes are made. |
| "COOL FAIL" flashes and unit doesn't run. Check for varying voltage on terminals. | Sensor not communicating with unit. Check voltage at terminals 11 and 12 at the unit. If voltage is steady at approximately 30VDC. check for open circuit in wiring. |
| "COOL FAIL + HEAT FAIL" icons flash simultaneously. | Check for defective outside air sensor. Emergency shutdown input may be open. If Heat Pump the Coil Temperature Sensor may have failed. |
| "HEAT FAIL" flashing. | A heat failure has occurred. If Heat Pump unit, the unit may be in emergency heat, or there is a defrost problem. |
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.