Goodman Mfg VC8 User Manual download pdf (Page 33)

COMFORTNET™ SYSTEM

NETWORK TROUBLESHOOTING

Communications is achieved by taking the difference

between two dc signals. The signals and transmission lines

are referred to as “data 1” and “data 2”. Each transmission

line is biased to approximately 2.5Vdc. During data recep-

tion/transmission, the data lines vary between +5V and

ground. (When data 1 is increasing towards +5V, data 2 is

decreasing towards ground and when data 1 is decreasing

towards ground, data 2 is increasing towards +5V. Typically,

the data 1 line is approximately 2.6Vdc and the data 2

transmission line is approximately 2.3Vdc. The voltage

difference between data 1 and data 2 is typically 0.2 to 0.6

Vdc.

The indoor control is equipped with a bank of three

dipswitches that provide biasing and termination functions for

the communications transmission lines. The outdoor control

in the CT compatible unit is equipped with a bank of two

dipswitches that provide termination functions for the com-

munications transmission lines. Communications errors will

result if these switches are not correctly set. The table

below indicates the switch position for the bias and termina-

tion dipswitches along with the expected voltages. Note that

the ON position is the correct position for all bias and

termination dipswitches.

ONOFF

BIAS

TERM

Indoor Unit BIAS and TERMINATION Dipswitches

The ComfortNet system is a fully communicating system, and

thus, constitutes a network. Occasionally the need to trouble-

Submenu Item User Modifiable Options Comments

Cool Airflow (CL CFM) 18, 24, 30, 36, 42, 48, or 60, default

is 18

Selects the airflow for the non-CT

compatible single stage AC unit

Cool Airflow Trim (CL TRM) -10% to +10% in 2% increments,

default is 0%

Selects the airflow trim amount for the non-

CT compatible single stage AC unit

Cool Airflow Profile (CL PRFL) A, B, C, or D, default is A Selects the airflow profile for the non-CT

compatible single stage AC unit

Cool ON Delay (CL ON) 5, 10, 20, or 30 seconds, default is

5 seconds

Selects the indoor blower ON delay for the

non-CT compatible single stage AC unit

Cool OFF Delay (CL OFF) 30, 60, 90, or 120 seconds, default

is 30 seconds

Selects the indoor blower OFF delay for the

non-CT compatible single stage AC unit

NON-COMM (APPLIES ONLY TO A CT COMPATIBLE FURNACE MATCHED

WITH A NON-CT COMPATIBLE SINGLE STAGE AIR CONDITIONER)

shoot the network may arise. The integrated furnace control

has some on-board tools that may be used to troubleshoot the

network. These tools are: red communications LED, green

receive (Rx) LED, and learn button.

• Red communications LED – Indicates the status of

the network. The table below indicates the LED status

and the corresponding potential problem.

• Green receive LED – Indicates network traffic. The

table below indicates the LED status and the

corresponding potential problem.

• Learn button – Used to reset the network. Depress

the button for approximately 2 seconds to reset the

network.

SYSTEM T ROUBLESHOOTING

NOTE: Refer to the instructions accompanying the CT

compatible outdoor AC/HP unit for troubleshooting information.

Refer to the Troubleshooting Chart in the Appendix for a listing

of possible furnace error codes, possible causes and correc-

tive actions.

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Goodman Mfg VC8 User Manual Page 33

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