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FAULT CONDITIONS
FAULTS, LOCKOUTS AND RECYCLING
In the following sections, the Controller shutting down the heat pump outputs means turning off all the outputs. In Cool Mode, the
RV output is not turned off. Unless otherwise specified in related fault conditions, Emergency Heat Mode shall be possible in
Volatile Lockout, Auto-Restart, and Anti-Short Cycle. The following are the system status definitions that the Controller goes into in
the presence of a fault or faults.
When there are two or more fault conditions present, the fault priority is established with the action required by the faults. The
following is the fault priority list from the highest priority to the lowest priority:
a. Volatile Lockout
b. Auto-Restart
c. Anti-Short Cycle
Volatile Lockout:
This is a status of the Controller where all outputs are shut down due to a fault condition and the heat pump is inoperable until the
RESET/TEST button is pressed for 1 second or the power is cycled. Unless otherwise specified, Volatile Lockout causes X/L to be
energized and the Controller shall display the Volatile Lockout Code and the fault code on the display.
Auto-Restart:
This is a status of the Controller where all outputs are shut down for 10 minutes after detecting a fault condition and at the end of
the 10 minutes, if no fault condition is present, the Controller returns to normal operation. If the fault condition still exists at the
end of the 10 minutes, the Controller stays in shut down until the fault condition clears. If Auto-Restart occurs three times after a
successful start up within a Heat/Cool demand call, the Controller goes into Volatile Lockout on the third attempt.
(NOTE) If the system is in Auto-restart for 30 minutes the system will then go into Volatile Lockout.
(NOTE) The Auto-Restart counter is reset after the completion of a successful Active Heat/Cool Mode. In Auto-Restart, the
Controller shall display the Auto-Restart code and the fault code on the display.
The following describes occurrences of two conditions and the actions taken with each:
Second Fault in Auto-Restart:
If a second fault condition occurs, which requires Anti-Short Cycle, while the Controller is in Auto-Restart; the Controller shall go
into Anti-Short Cycle. If at the end of the Anti-Short Cycle both faults are still present and one of them requires Anti-Short Cycle,
the Controller stays in Anti-Short Cycle. If at the end of the Anti-Short Cycle, there are faults that require only Auto-Restart, the
Controller shall go into Auto-Restart. If the second fault condition, which occurs while the Controller is in Auto-Restart, requires
Volatile Lockout, the Controller goes into Volatile Lockout immediately.
Second Fault in Anti-Short Cycle:
If a second fault condition occurs, which does not require Volatile Lockout, while the Controller is in Anti-Short Cycle, the
Controller shall complete a 2
nd
Anti-Short Cycle. At the end of the 2
nd
Anti-Short Cycle, if there is still a fault that causes Anti-
Short Cycle, the Controller stays in Anti-Short Cycle. At the end of the 2
nd
Anti-Short Cycle, if there are faults that cause only
Auto-Restart, the Controller goes into Auto-Restart and follows the normal Auto-Restart procedure. If the 2
nd
fault condition,
which occurs while the Controller is in Anti-Short Cycle, requires Volatile Lockout, the Controller goes into Volatile Lockout
immediately.
IMPORTANT: If there are more than two fault conditions, the fault handling strategies that are described above can be applied in a
similar fashion. Some of the faults below require a 30-minute counter in order to energize the X/L output if the fault condition
persists for 30 minutes. In those cases, there shall be only one 30-minute counter. The continuous presence of any number of these
kinds of faults will keep this counter running until 30 minutes has elapsed. The following are the definitions of the fault conditions
that are detected by the Controller.
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