Trouble Shooting; Protective Function; Self-Diagnosis - Midea MFJ-24ARN1-QB8 Technical & Service Manual

9

Trouble shooting

9.1 Protective Function

9.1.1 3-minute delay for the compressor start-up
At the beginning of energizing or after the stop of the compressor, 3-minute delay will be needed
to start the compressor.
When switching over between cooling/heating mode, the compressor stops automatically.
9.1.2 Evaporator protection against high temperature
9.1.2.1 Only available under heating mode.
9.1.2.2 The operation principle is as follows: (T2 = evaporator temperature)
Condition
T2>56° C
T2>62° C
T2<62° C
T2<50° C
Note: During protection, the indoor fan continues operating at a set speed, while the anti-cold air
function of heating and the compressor will be 3 minute delayed to shut down for protection.
9.1.3 Evaporator Protection against low temperature
9.1.3.1 Only available under cooling and dehumidifying status.
9.1.3.2 Protection principle:
Condition
T2<2° C l ast 3 minute
（
T2>8° C
9.1.3.3 The restart of the compressor shall execute the delay protection.
9.1.4 Condenser high temperature protection
9.1.4.1 Only available to cooling and dehumidifying mode.
9.1.4.2 Action condition
Condition
Condenser temp.>62° C
Condenser temp.<48° C
9.1.4.3 Delay protection should be performed when the compressor restarts.
9.1.5 Outdoor protection
When outdoor protection signal is high level, outdoor unit will perform protection: the whole
machine will be shut down while the indoor unit will indicate the corresponding protection signal.
The A/C will recover if outdoor errors are eliminated after the outdoor protection occurs.

9.2 Self-diagnosis

Codes Contents
P4 Protection of temperature of indoor evaporator
P5 Protection of temperature of outdoor condenser
P9 Protection of defrosting or anti-cold wind
E1 Open-circuit and short-circuit of temperature sensors T1
E2 Temp. sensor T2 on indoor evaporator is open circuit or short circuit
Outdoor fan
Off
Off
On
On
Outdoor fan
Off
）
On
Outdoor fan
Off
On
21
Exploded view & spare-part
Compressor
On
Off
Off
On
Compressor
Off
On
Compressor
Off
On