Rollout Limit; Pressure Switches; Troubleshooting; Electrostatic Discharge (Esd) P - Goodman xMEC96 Series User Manual

R L
OLLOUT IMIT
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.
P S
RESSURE WITCHES
The pressure switches are normally-open (closed during operation) negative air pressure-activated switches. They monitor 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 conditions.
F S
LAME ENSOR
The flame sensor is a probe mounted to the burner/manifold assembly which uses the principle of flame rectification to determine the
presence or absence of flame.
T
ROUBLESHOOTING
E D
LECTROSTATIC ISCHARGE
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 damage. By
putting the furnace, the control, and the person at the same electrostatic potential, these steps will help avoid exposing the inte-
grated 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.
C F S
HECKING LAME ENSOR
Flame current can be measured in two ways:
1. Putting a D.C. microamp meter in series with the flame rod
2. Putting a D.C. volt meter across the two solder pads in the flame
current section of the control board.
1 D.C. volt = 1 microamp. See Figure 36.
L F C
IMIT AULT ODES
If the control detects the high limit circuit open, the RED LED will flash
FOUR times and energize the inducer and indoor blower.
If the limit circuit opens five times within a single call for heat, the
furnace will go into lockout for one hour. The RED LED will display a FOUR
flash code during this time. The control board can be reset by cycling 115
volt power to the furnace.
If the limit circuit opens and does not close within five minutes, the
control assumes the blower has failed the RED LED will flash ELEVEN times.
If the limit circuit opens and does not close within fifteen minutes, the
control assumes the manual rollout or fuse has opened and the RED LED
will flash FIVE times. The control will enter a one hour lockout and the inducer will run continuously.
In an open limit condition the red LED will flash as described above but the error code will not be stored in memory until the
limit resets or until 15 minutes has elapsed. So if the limit resets in less than 5 minutes a four flash code will be stored. If the
limit resets in more than 5 but less than 15 minutes, an eleven flash code will be stored. If the limit is still open after 15
minutes, a five flash code will be stored.
(ESD) P

RECAUTIONS

Flame Current
Solder Pads
39
Figure 36