AERCO Esteem O&M Manual - Manual (Page 79)

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Boiler Control Module Display Messages
check the DHW thermostat wiring and thermostat control. Replace as needed. Remove jumper
when completed.
• Disconnect power to the boiler. Check all wiring and wiring connections and compare to the wiring
diagram. Ensure all wiring and wiring connection are in good condition and secure. If necessary,
replace complete wiring harness.
• Check for 24 volts across the control module internal fuse F3, which is located toward the middle
of the control see Figure 27 on page 71.. If necessary replace the fuse. See “Control Module Fus-
es” on page 70, for accessing the internal fuses of the control module.
• Check Item 6 in the INFO mode. If Item 6 shows a reading of 32, remove the air inlet tube from
venturi on the Blower/Burner Assembly. Looking into the inlet of the venturi, check for any rotation
of the blower impeller. If the blower impeller is rotating, replace the blower.
• If all the above steps fail to resolve the problem, replace the control module.
Boiler Display shows FUSE
• Check and ensure the transformer is properly connected to the MCBA module.
• Check and ensure 24V are measured at the transformer when properly connected to the MCBA
module. If necessary, replace the transformer.
• Check the internal fuse F3 by locating the control module and removing the black housing. The
internal fuse F3 is located in the center of the control module as shown in Fig. 1 page 4.
• See “Control Module Fuses” on page 70, for accessing the internal fuses of the control module.
• If fuse F3 has blown, replace the fuse with a 4-amp/250V slow acting fuse. Check external boiler
wiring for external source of 24V feedback.
GF-125