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Green LED – on control board.
Full on = low voltage present and okay, micro controller is functioning, etc.
One pulse = electric heating element is active (set point is still controlling actual element on/off).
Two pulses = bad outlet temperature sensor.
Three pulses = control hi-limit open.
R to W closed contact – external switch device.
Fan is running.
Inlet damper is opening and held open.
- Inlet damper is spring close.
Control board – heat active (set point is still controlling actual element on/off).
Fan relationship to electric heating elements – fan comes on immediate with R to W contact. There is
a 30-second delay before elements turn on (outlet sensor needs to measure inlet air, not room air). The
fan also purges the inside elements and warm air after R to W is open for 60 seconds.
Hi-limit, manual reset – all operations seem normal, but the heating element power is interrupted.
The reset button is in the hinged door compartment, on control box divider.
Auto reset hi-limits – there are two.
Temperature control, at fan inlet, this is set for an approximate 90° F outlet temperature. It is in
the low voltage logic control circuit. LED will show 3 pulses.
Comment – this is in addition to the outlet temperature sensor mounted within the discharge duct
which responds to the set point temperature dial.
Element current carrying leg – within the sheet metal housing/inside deflectors, this is a safety hi-
limit in case there is a fan failure or major inlet air restriction.
Disconnected or bad detected sensor – LED will show two pulses. The electric elements or heat active
is at 100% on, follows the R-W input. With an inactive duct sensor the electric elements are no longer
controlled at set point.
12/30/2020
Operational Indicators
11
EI916
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