Trane UniTrane Installation Operation & Maintenance page 112

Table 48. Electric Heat Not Operating
Probable Cause
Normal Operation
Unit Disabled
Electric Heat Control: Disable
Maximum heating capacity of zero The Tracer
Latching Diagnostic Present
Autocycle Test
Unit Configuration
No Power to the TUC
Wiring
112
Explanation
The controller cycles electric heat on and off to meet the unit
capacity requirements.
The TUC may be disabled via the shutdown mode on a Tracer
system or if BIP1 is configured as external interlock.
The electric heat may be disabled with the Tracer
enable the electric heat, the TUC electric heat control must be set
to the auto postion.
® may limit the maximum heating/cooling capacity of the
TUC from zero to 100%. When the maximum heating capacity is
zero, the electric heat is disabled.
A specific list of diagnostics affects electric heat operation. For
more information, see the "Diagnostics" section on page 73.
Latching diagnostics require a manual reset to restore normal unit
operation.
The controller includes an autocycle test sequence that verifies
analog and binary output operation and associated output wiring.
However, based on the current stage in the test sequence, the
electric heat may be disabled. Refer to the "Autocycle Test"
section on page 71.
The TUC cannot control the electric heat output if the unit is config-
ured for no electric heat. Also, if the electric heat type is incorrectly
configured (1 or 2 stage), the electric heat may not operate prop-
erly.
The TUC requires 24 VAC power for the unit to operate properly.
The wiring between the controller outputs and the electric heat must
be present and correct for normal electric heat operation. Refer to
the typical unit wiring diagrams on pages 105-106.
Terminal Unit
Control (TUC)
®
system. To
UNT-IOM-6
®