Goodman Mfg VC8 High Voltage, Troubleshooting & Maintenance, Safety Circuit Description

TROUBLESHOOTING & MAINTENANCE

Burner Flame

SAFETY CIRCUIT DESCRIPTION

A number of safety circuits are employed to ensure safe and proper furnace operation. These circuits serve to control any potential safety hazards and serve as inputs in the monitoring and diagnosis of abnormal function. These circuits are con- tinuously monitored during furnace operation by the integrated control module.

INTEGRATED CONTROLMODULE

The integrated control module is an electronic device which, if a potential safety concern is detected, will take the necessary precautions and provide diagnostic information through an LED.

PRIMARY LIMIT

The primary limit control is located on the partition panel and monitors heat exchanger compartment temperatures. It is a normally-closed (electrically), automatic reset, temperature-ac- tivated sensor. The limit guards against overheating as a result of insufficient conditioned air passing over the heat exchanger.

AUXILIARY LIMIT

The auxiliary limit controls are located on or near the circulator blower and monitors blower compartment temperatures. They are a normally-closed (electrically), auto-reset sensors. These limits guard against overheating as a result of insufficient con- ditioned air passing over the heat exchanger.

ROLLOUT LIMIT

The rollout limit controls are mounted on the burner/manifold assembly and monitor the burner flame. They are normally- closed (electrically), manual-reset sensors. These limits guard against burner flames not being properly drawn into the heat exchanger.

PRESSURE SWITCHES

The pressure switches are normally-open (closed during op- eration) negative air pressure-activated switches. They moni- tor the airflow (combustion air and flue products) through the heat exchanger via pressure taps located on the induced draft blower and the coil front cover. These switches guard against insufficient airflow (combustion air and flue products) through the heat exchanger and/or blocked condensate drain condi- tions.

FLAME SENSOR

The flame sensor is a probe mounted to the burner/manifold assembly which uses the principle of flame rectification to de- termine the presence or absence of flame.

TROUBLESHOOTING

ELECTROSTATIC DISCHARGE (ESD)PRECAUTIONS

NOTE: Discharge body’s static electricity before touching unit. An electrostatic discharge can adversely affect electrical components.

Use the following precautions during furnace installation and servicing to protect the integrated control module from dam- age. By putting the furnace, the control, and the person at the same electrostatic potential, these steps will help avoid expos- ing the integrated control module to electrostatic discharge. This procedure is applicable to both installed and uninstalled (ungrounded) furnaces.

1.Disconnect all power to the furnace. Do not touch the integrated control module or any wire connected to the control prior to discharging your body’s electrostatic charge to ground.

2.Firmly touch a clean, unpainted, metal surface of the furnace away from the control. Any tools held in a person’s hand during grounding will be discharged.

3.Service integrated control module or connecting wiring following the discharge process in step 2. Use caution not to recharge your body with static electricity; (i.e., do not move or shuffle your feet, do not touch ungrounded objects, etc.). If you come in contact with an ungrounded object, repeat step 2 before touching control or wires.

4.Discharge your body to ground before removing a new control from its container. Follow steps 1 through 3 if installing the control on a furnace. Return any old or new controls to their containers before touching any ungrounded object.

DIAGNOSTIC CHART

WARNING

HIGH VOLTAGE !

TO AVOID PERSONAL INJURY OR DEATH DUE TO

ELECTRICAL SHOCK, DISCONNECT ELECTRICAL POWER

BEFORE PERFORMING ANY SERVICE OR MAINTENANCE.

Refer to the Troubleshooting Chart at the end of this manual for assistance in determining the source of unit operational prob- lems. The dual 7-segment LED display will display an error code that may contain a letter and number. The error code may be used to assist in troubleshooting the unit.

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