Operation/Service Section
Controls - Location, Operation, and Service
To service this system, it is necessary to understand the normal operation of the controls and the function of the diagnostic circuit board. Refer to the electrical box drawing in Figure 7 and to the individual illustrations to identify and locate each of the controls. The wiring diagrams for this unit are located in the main electrical box.
WARNING: Service work on this system should only be done by a qualified gas ser- vice person. The service information and the troubleshooting guides are intended as an aid to a qualified service person.
Figure 7 - Control Locations
Control | Outside Air Cutoff | Time Delay |
|
Relays | (high ambient limit control) | Relay |
Ignition
Module
Maxitrol Amplifier | Circuit |
or Signal Conditioner | Board |
|
Bypass
Damper
Motor
Status Lights | Transformer | |
Service | ||
Switches | 24 |
|
Return
Air
Damper
Motor
Motor
Starter
High 
Low
Optional | Optional Bypass Damper | Standard Pressure | Relay for |
Dirty Filter | Pressure Switches | Switches | Optional |
Pressure Switch |
|
|
|
NOTE: Wiring diagrams for the unit are located on the inside of the electrical box door.
Starter | Line Voltage |
Relay | Terminals |
7.Electronic Circuit Board with Diagnostic Lights
Location: Control Compartment Electrical Box (See Figure 7)
Function: The diagnostic lights on the circuit board are designed to assist in troubleshooting. When the system is operating properly, the lights on the circuit board are lit. If the system fails to operate properly, all lights on the circuit board up to that one that represents the component or system that has failed will be lit. For more detailed information, refer to the Trouble- shooting Guide in Paragraph 19.
Figure 8 - |
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Diagnostic |
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Column of 13 | |||
Circuit | |||
Board, | indicator | ||
P/N 151263 | bulbs; always | ||
| replace | ||
| burned out | ||
| bulbs, P/N | ||
| 125189. | ||
8. Temperature Limit Safety Controls
Location: 1) Manual Reset Limit Switch is mounted on a 2x4 electrical box located in the blower section. To access the manual reset, remove the blower section access panel to the left of the discharge (left when facing the discharge); 2) Emergency Cutoff Limit Control is in the burner/control cabinet just above the electri- cal box.
• Manual Reset Limit Control - Blower | ||
Cabinet |
| |
Figure 9 - | ||
Function: The | ||
Manual Reset | ||
manual reset limit | ||
Limit | ||
is a temperature | ||
| ||
activated safety | Capillary tubing is | |
control. | ||
in a holder that | ||
of the system can | ||
extends into the | ||
be done only after | ||
the limit control is |
| |
cooled and the reset button is depressed.
CAUTION: If the manual reset limit activates, find and correct the cause before
Service: Failure of the manual reset limit requires replacement of the control.
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