Haier AW07LC2VHA Technical Overview page 41

Testing Communication Circuit
Testing Communication Circuit
If an Error E7 occurs, perform the following test to determine
if the indoor control board is functioning properly to send data
to the outdoor unit.
Perform this test with the unit powered and all wiring
connected between indoor and outdoor unit.
Make sure all wiring between the indoor and outdoor unit
are correct. There should no splices between the indoor and
outdoor unit wiring connecting terminals 1 or 3. Make sure
wiring is correct, before performing this test.
1. Measure the DC voltage between terminals 1 and 3
on the indoor terminal block.
2. The voltage should fluctuate between 8VDC and
23VDC. The fluctuating signal indicates a
good communication path.
3. If the voltage does not fluctuate, and the wiring is
good, the indoor board is defective.
INDOOR WALL MOUNT UNIT SECTION
TESTING
Antifreezing Protection
Antifreezing Protection
Prevents freeze-up of the indoor coil
The indoor unit coil temperature sensor will shut off the
outdoor unit and begin a defrosting routine if the indoor coil
is below 32°F for more than 2 minutes. The indoor unit will
not report this operation. Once the indoor coil warms up, the
system will re-enter cooling mode and operate normally, This
protection cycle prevents the indoor coil from developing ice
coating during low heat load operation.
Indoor Coil Sensor
PAGE 41