Troubleshooting - Aprilaire 8400 Series Safety & Installation Instructions

TROUblESHOOTINg

DISplAY IS blANK
• C heck circuit breaker and reset if necessary.
• M ake sure power switch at heating & cooling
system is on .
• M ake sure furnace door is closed securely.
• I f thermostat is battery powered, make sure fresh AA
alkaline batteries are correctly installed.
TEmpERATURE SETTINgS DO NOT CHANgE
Make sure heating and cooling temperatures are set to
acceptable ranges:
• Heat: 45° to 90°F (7° to 32°C).
• Cool: 50° to 99°F (10° to 37°C).
61000652C 8400 Tstat Install.indd 25
HEATINg SYSTEm DOES NOT RESpOND
("HEATINg" AppEARS ON SCREEN)
• C heck for 24 VAC at the equipment on the secondary
side of the transformer between power and
common. If voltage is not present, check the heating
equipment to find the cause of the problem.
• C heck for 24 VAC between the heat terminal (W)
and the transformer common. If 24 VAC is present,
the thermostat is functional. Check the heating
equipment to find the cause of the problem.
• C heck for loose or broken wires between the
thermostat and the heating equipment.
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10/13/09 11:09:03 AM