Haier HCFU-42CF03 Service Manual page 43

Diagnose and troubleshooting:
1) Sensor failure
check if the wiring is
correct according to
wiring diagram
if sensor is fixed
well
yes
Is sensor short-circuit
or open-circuit?
yes
Is sensor resistance
acceptable?
yes
Is DC voltage between
both ends of sensor
near 5V or 0V?
no
Replace PCB
2) Communication failure between operation panel and indoor unit
s ta rt
if th e w ire d c o n tro lle r
a n d in d o o r P C B a re
c o m p a tib le
y e s
if te rm in a ls A ,B ,C ,D o n
w ire d c o n tro lle r a re
c o rre s p o n d in g w ith
te rm in a ls o f in d o o r P C B
y e s
if te rm in a ls A ,B ,C ,D o f
w ire d c o n tro lle r a re in
o p e n c irc u it o r
c o n n e c te d w e ll
y e s
if te rm in a ls A ,B (o r
C ,D )o f w ire d c o n tro lle r
a re s h o rt c irc u it
43
Commercial Air Conditioner
no
reconnect
no
Relocate
yes
Replace sensor
no
Replace sensor
n o
c h a n g e w ire d
c o n tro lle r
n o
w ire c o rre c tly
n o
w ire c o rre c tly
y e s
w ire c o rre c tly
Model: HCFU-42CF03
HCFU-42HF03