Trane Tracer Unit Ventilator, ZN.520 Freeze Protection, Fan Failure, Space Temperature Failure

Troubleshooting

Safeties

Freeze Protection

The Tracer ZN.520 controller has two methods of freeze protection.

1.An optional binary freezestat that is wired to a binary input. The freezestat is a capillary tube type and is factory set to 35 °F. When this device opens, a “Low Coil Temp Detect” diagnostic is generated.

2.Using the discharge air tem- perature sensor, if the dis- charge air temperature falls below the discharge air low limit, the controller increases the heating capacity to temper the air. If the discharge air temperature remains below the discharge air low limit for 3 minutes, the controller gen- erates a “Low Coil Temp Detect” diagnostic.

Fan Failure

A “Low Air Flow—Fan Failure” di- agnostic is generated when a fan status device is present and fails to close after 1 minute of unit start-up or when it opens for more than 1 minute during normal unit opera- tion.

Space Temperature

Failure

If the Tracer ZN.520 has validated a space temperature input and then the input becomes invalid, a space temperature failure diag- nostic occurs.

Entering Water

Temperature Failure

If the Tracer ZN.520 has validated an entering water temperature in- put and then the input becomes in- valid, an entering water temp- erature failure diagnostic occurs.

Discharge Air

Temperature Limit

When the discharge air exceeds the high or low limit setpoint and the unit can not correct it by alter- ing capacity, a “Discharge Air Temp Limit” diagnostic is generat- ed.

Outdoor Air Temperature

Failure

If the Tracer ZN.520 has validated an outdoor air temperature input and then the input becomes in- valid, an outdoor air temperature failure diagnostic occurs.

Humidity Input Failure

If the Tracer ZN.520 has validated a relative humidity input and then the input becomes invalid, a hu- midity input failure diagnostic oc- curs.

CO Sensor Failure

2

If the Tracer ZN.520 has validated a CO2 input and then the input be- comes invalid, a CO input failure

2

diagnostic occurs.

Generic AIP Failure

If the Tracer ZN.520 has validated a generic analog input and then the input becomes invalid, a ge- neric analog input failure diagnos- tic occurs.

Defrosting-Compressor

Lockout

The defrost stat used with Tracer ZN.520 on DX units is wired in se- ries with the condensing unit.

When it opens to indicate a frost condition, the Tracer ZN.520 sens- es the open circuit and de-energiz- es the condensing unit output. A defrosting diagnostic is generated at this point.

Maintenance Required

Note: If power to the unit is cycled or discontinued for any reason, all maintenance timers are automatically reset.

The “Maintenance Required” di- agnostic is generated when the fan run-time exceeds the configurable limit. This diagnostic is useful for filter change notification.

Local Fan Mode Failure

If the hardwired fan mode input to the Tracer ZN.520 controller is present and then becomes invalid, a local fan mode failure diagnostic is generated.

Local Setpoint Failure

If the hardwired setpoint input to the Tracer ZN.520 controller is present and then becomes invalid, a local setpoint failure diagnostic is generated.

Generic Temperature

Failure

If the Tracer ZN.520 has validated a generic temperature input and then the input becomes invalid, a generic temperature input failure diagnostic occurs.

Invalid Unit

Configuration

If the Tracer ZN.520 has been con- figured improperly or loses its configuration, an invalid unit con- figuration diagnostic is generated. The unit must be re-configured with a valid configuration to cor- rect this problem.

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