P0/P4/H6: High Temperature Protection - Midea VRF V4 Plus I Series Manual

MCAC-VTSM-2014-04
5.8 P0/P4/H6: High temperature protection (Display on faulty unit, all the ODU in standby)
P0: Inverter compressor top temperature protection
When the top temperature is over 120℃, the operation will stop, when the temperature goes back to normal
range, P0 disappear and normal operation resumes.
P4: High discharge temperature protection
When the discharge temperature of any compressor is over 120℃, the operation will stop, when the
temperature goes back to normal range, P4 disappear and normal operation resumes.
H6: When system appear 3 times P4 protection in 100 minutes
It cannot resume automatically, and it can resume only by restarting the machine.
P0/P4/H6
T7/T7C1/T7C2 sensor is
short circuit or disabled
No
System is lack of refrigerant
(Refrigerant recharging is not
according to the requirement,
or there has refrigerant
leakage)
No
The low pressure side is blocked
for squashed pipe, closed EXV,
closed strop valve, dirty filter, etc.
No
The indoor load is too large
No
System contains air or nitrogen
No
MC9S08AC128
disabled
No
Main board is disabled
Note:
1. How to check whether the T7/T7C1/T7C2 sensor is short circuit or disabled
Using a multimeter to measure resistance, if the resistance is too small, the sensor is short circuit, if the resistance in certain
temperature is not consistent with attached table 2, the sensor is disabled
2. The phenomenon of lack of refrigerant
Top temperature and discharge temperature of all compressors are higher than normal value, discharge pressure and suction
pressure are both lower than normal value, current is lower than normal value, suction pipe may be frosting. All the
phenomenon will disappear after recharging refrigerant.
3. The phenomenon of the low pressure side is blocked
The discharge temperature is higher than normal value*, low pressure is lower than normal value*, current is lower than
normal value* and suction pipe may be frosting.
4. The phenomenon of the indoor load is too large
The suction temperature and discharge temperature are both higher than normal value.
5. The phenomenon of the system contains air or nitrogen
The high pressure is higher than normal value, current is larger than normal value, discharge temperature is higher than
normal value, compressor makes noise, pressure meter do not display steady.
*The normal system running parameters please refer to attached table 3.
Troubleshooting
Yes
①
.
②
.
Yes
③
Yes
Yes
④
Yes
⑤
Yes
chip is
②
:
③
:
④
:
Replace the sensor
Add refrigerant or check up
the leakage of the system
Make sure all valves are open, clean the
filter, if the filter is blocked by ice, the
system should be clean
Make sure the ratio of connectable IDU is
less than 130% or add ODU
Discharge the entire refrigerant. Then vacuum
the system and refill the refrigerant. Add oil to
the system if it leaks.
Replace main board
①
:
⑤
:
R410A DC Inverter V4 Plus 50Hz
103