Aprilaire 8400 series - Troubleshooting

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TROUBLESHOOTING
DISPLAY IS BLANK
•Checkcircuitbreakerandresetifnecessary.
•Makesurepowerswitchatheating&cooling
system is on.
•Makesurefurnacedoorisclosedsecurely.
•If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).
HEATING SYSTEM DOES NOT RESPOND
(“HEATING” APPEARS ON SCREEN)
•Check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.
•Check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.
•Checkforlooseorbrokenwiresbetweenthe
thermostatandtheheatingequipment.
61000652C 8400 Tstat Install.indd 25 10/13/09 11:09:03 AM