Multi-Zone Technical Overview

Table Of Contents

TESTING

PAGE 42

ENGLISH

INDOOR WALL MOUNT UNIT SECTION

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 uctuate between 8VDC and

23VDC. The uctuating signal indicates a

good communication path.

3. If the voltage does not uctuate, and the wiring is

good, the indoor board is defective.

Antifreezing Protection

Prevents freeze-up of the indoor coil

The indoor unit coil temperature sensor will shut o 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