Trane TVR Pro CO Series - 2.21 P4, H6: Discharge temperature protection; 2.21.1 Digital display output; 2.21.2 Description; 2.21.3 Trigger; recover condition

104
2.21 P4, H6: Discharge temperature protection
Digital display output
;
Description
 Discharge temperature protection.
 All units stop running.
 Error code is only displayed on the unit with the error.
Trigger / recover condition
 Trigger condition:
For P4 protection: Discharge temperature (T7C1/2) ≥ 120
o
C.
For H6 protection: P4 protection appears three times in 100 minutes.
 Recover condition: Discharge temperature (T7C1/2) ≤ 90
o
C.
 Reset method:
For P4 protection: Resume automatically.
For H6 protection: Manually restart.
Possible causes
 Outdoor unit stop valves are closed.

Temperature sensor/switch not connected
properly or has malfunctioned.
 Insufficient refrigerant.
 System blockage.
 Indoor load too large.
 System contains air or nitrogen.
 Poor condenser heat exchange.
 Main PCB damaged.
Procedure
P4 / H6
ODU stop valves are closed
Yes
Open the stop valves
No
Compressor top temperature sensor,
discharge pipe temperature sensor
and/or discharge temperature switch
connections on main PCB are loose
1
Yes
Ensure the sensors and switch are
connected properly
No
Compressor top temperature sensor
and/or discharge pipe temperature
sensor have short circuited or failed
2
Yes
Replace the faulty sensor(s)
No
Flowchart continued on next page …
… flowchart continued from previous page