Error Code 21 - Bosch AHUW036A2 Service Manual

Error handling instructions for Split outdoor unit
HMI Error code ODU Error code Description
5664, 5665 48
5632, 5633 52
5634, 5635 53
5636, 5637 54
5668, 5669 55
5638, 5639 60
5640, 5641 61
5642, 5643 62
5646, 5647 65
5670, 5671 67
Table 3 Error codes
When the outdoor unit (ODU) is blocked the error can be
acknowledged by power ON/OFF.
2.3

Error code 21

Display
code Title Cause of error
21 DC PEAK -Instant over
(IPM fault) current
-Over rated
current
-Poor insulation
of IPM
Table 4 Error code 21
ODU model Resistance () at 25 °C
ODU Split 4 U-V
V-W
ODU Split 6
W-U
ODU Split 8
ODU Split 11s U-V
V-W
ODU Split 13s
W-U
ODU Split 15s
ODU Split 11t U-V
V-W
ODU Split 13t
W-U
ODU Split 15t
Table 5 Resistance between phases
4
Cond. Out-pipe Th Error (Open/
Short)
Bad communication between
Inverter-PCB and Main-PCB
Bad communication between Can-
PCB and Main-PCB
Phase sequence incorrect
CAN Communication error (CAN-
PCB <=> Installerboard)
EEPROM Checksum mismatched
Temperature at condenser-pipe is
too high
Temperature at heat sink is too
high
Problem in heatsink temperature
sensor
ODU BLDC fan lock
Check point & Normal
condition
-An instant over current in
the U,V,W phase
-Comp lock
-The abnormal connection of
U,V,W
-Over load condition
-Overcharging of refrigerant
pipe length
-Outdoor fan has stopped
-Poor insulation of
compressor
0.628
0.628
0.628
0.438
0.438
0.438
0.845
0.845
0.845
Error characteristc Remark
Sensor TH6 broken (5k
Direct shut-down
Restart 3x/hour, Wiring between Mainboard and Inverter board
then blocked damaged (3~ phase only)
Wiring between Mainboard and CAN-PCB
Direct shut-down
damaged
Restart 10x/hour, only 2 phases or incorrect rotation field
then blocked (3~ phase only)
Wiring between CAN-PCB and Indoor unit
Direct shut-down
damaged
Change EEPROM
Direct shut-down
Restart after Condensing temperature >65.3°C (4199 kPa)
problem has {Heating}
vanished Condensing temperature >64.2
{Cooling}
Restart after Heat sink temperature >85
problem has
vanished
Heat sink sensor / Inverter-PCB broken
Direct shut-down
Restart 10x/hour, Fan blocked
then blocked
1
U
V
2
1
Fig. 1 Resistance measurement on compressor
[1] Compressor
[2] Copper pipe

>25 )
°C
°C (4101 kPa)
°C
W
6 720 817 722-01.1I
Split ODU – 6 720 817 722 (2015/06)