GVZC20 Service Manual

SERVICING

COMMUNICATING BOARD

INDOOR UNIT TROUBLESHOOTING FOR TXV APPLICABLE UNIT (MBVC**00AA-1)

AUXILIARY ALARM SWITCH

The control is equipped with two Auxiliary Alarm terminals,

labeled CAS, which are typically utilized in series with a

condensate switch but could also be used with compatible

CO2 sensors or re alarms.

This feature can be activated or deactivated through the

thermostat user menus. The auxiliary alarm switch must be

normally closed and open when the alarm occurs. For ex-

ample, a normally closed condensate switch will open when

the base pan’s water level reaches a particular level. The

control will respond by turning o󰀨 the blower motor and out-

door unit and displaying the proper fault codes. If the switch

is later detected closed for 30 seconds, normal operation

resumes and the error message is removed. The error will

be maintained in the equipment’s fault history. See FIGURE

15 on the following page for the connection location.

CIRCULATOR BLOWER

This air handler is equipped with a variable speed circulator

blower. This blower provides several automatically-adjusted

blower speeds. The Specication Sheet applicable to your

model provides an airow table, showing the relationship

between airow (CFM) and external static pressure (E.S.P.).

The electric heat dip switch default position is set to the

OFF, OFF, OFF position and should be adjusted by the in-

staller to match the installation requirements for the correct

electric heating CFM.

Using the Electric Heat Airow table below, set dip switch-

es 9, 10, and 11 for the installed heater kit. Verify selected

CFM by counting the green CFM LED blinks. The green

CFM LED blinks once for each 100 CFM of airow.

If an electric heater kit has not been installed, set dip

switches 9, 10, and 11 to any appropriate heater kit setting

(see next page table for valid settings).

During the cooling operation, the outdoor unit will determine

the indoor airow.