All installations and services must be performed by qualified service personnel.
37
IV. Troubleshooting
NOTICE:
BEFORE TROUBLESHOOTING, FAMILIARIZE YOURSELF WITH
THE START UP AND CHECKOUT PROCEDURE.
ALL INSTALLATION AND SERVICES MUST BE PERFORMED BY QUALIFIED
HEATING CONTRACTORS.
To assist you in troubleshooting this furnace, it is equipped with an integrated
ignition control with diagnostics. These diagnostics evaluate what control system
has experienced a failure and activate a flashing light on the control in different
sequences to help pinpoint the failure which has occurred. Also provided in
appendix C is a troubleshooting flow chart located in the back of this manual.
IMPORTANT:
For your convenience, Thermo Products has installed a sight
glass in the blower door of this furnace. The number of flashes in groups should
be observed through this sight glass and recorded before turning off power to the
furnace. Otherwise power to the furnace will be interrupted upon or removing the
blower turning off power or removing the necessary to restart the furnace and
have the failure occur again.
DIAGNOSTIC FEATURES
The 50A65 control used on this furnace continuously monitors its operation and
the operation of the system. If a failure occurs, the LED light on the control will
failure code.
If the failure is internal to the control, the light will stay on
continuously. In this case, the entire control should be replaced, as the
control is not field-repairable.
If the sensed failure is in the system (external to the control), the LED will flash in
the following flash-pause sequences to indicate failure status (each flash will last
approximately 0.25 seconds and each pause will last approximately 2 seconds).
1 flash, then pause
System lockout
2 flashes, then pause
Pressure switch stuck closed
3 flashes, then pause
Pressure switch stuck open
4 flashes, then pause
Open high limit, aux. limit, or roll-out switch
6 flashes, then pause 115 Volt AC power reversed
7 flashes, then pause
Low flame sense signal
8 flashes, then pause
Check ignitor or improper grounding
Continuous flashing
Flame has been sensed when no flame should
(no pause)
be present (no call for heat)
The LED will also flash once at power-up.
Summary of Contents for MDA1-100N
Page 55: ...All installations and services must be performed by qualified service personnel 51...
Page 57: ...All installations and services must be performed by qualified service personnel 53...
Page 59: ...All installations and services must be performed by qualified service personnel 55...
Page 62: ......
