User`s manual

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41
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Table 22 — Durablade Economizer Service Analysis
(Table continued on page 42.)
PROBLEM CAUSE REMEDY
Damper does not open.
Indoor (evaporator) fan is off. 1. Check to ensure that 24 vac is present at terminal C1
on the IFC or that 24 vac is present at the IFO terminal.
Check whether 24 vac is present at PL6-1 (red wire)
and/or PL6-3 (black wire). If 24 vac is not present,
check wiring (see unit label diagram).
2. Check proper thermostat connection to G on the con-
nection board.
No power to economizer motor. 1. Check that SW3 is properly making contact with the
damper blade. Check that SW1 is in the NC (normally
closed) position.
2. Check diode D18. If diode is not functioning properly,
replace economizer control board.
3. Confirm that the economizer control board is grounded
properly at PL6-4 (brown wire) and at brown terminal
of the economizer control board (brown wire). The
economizer motor must also be grounded properly at
the negative motor terminal (brown wire).
4. Verify SW1 and SW3 are working and wired properly
(see unit label diagram).
5. Check for 24 vac input at both PL6-1 (red wire) and
PL6-3 (black wire). If 24 vac not present, check unit
wiring (see unit label diagram). If 24 vac is found in
both places, check for 24 vac at the yellow terminal of
the economizer control board (yellow wire). If 24 vac
power is not present, replace the economizer control
board.
Economizer motor failure. If the indoor (evaporator) fan and economizer motor are
energized, verify that there is a minimum of 18 vdc at the
positive motor terminal. If the motor is not operating, re-
place the motor.
Economizer operation limited
to minimum position.
OAT or EC set too high. 1. Set at correct temperature (3 F below indoor space
temperature).
2. Check OAT or EC by setting above outdoor temperature
or humidly level. If the OAT or EC switches do not
close, replace OAT or EC.
Verify economizer control board
is correctly wired and works
properly.
1. Perform the following tests when OAT or EC is closed,
Y1 is called for and damper is at minimum position.
Confirm 24 vac on gray terminal of the economizer con-
trol board (gray wire). If 24 vac is not present, check
wiring (see unit label diagram).
2. Verify that SW1 and SW3 are wired correctly and work-
ing properly (see unit label diagram).
3. Check to ensure that 24 vac exists at PL6-2 (blue
wire). If 24 vac is not present, check wiring (see unit
wiring label diagram).
4. Check 24 vac output at PL6-10 (white wire). If 24 vac
is not present, replace economizer control board.
Check SAT. 1. After verifying that the OAT and EC settings and the
economizer control board wiring are correct, check to
ensure that the 24 vac terminal of the SAT has 24 vac
(white wire). If OAT, EC, and control board are function-
ing and wired properly and no 24 vac exists, check wir-
ing (see unit label diagram).
2. If supply-air temperature is greater than 57 F, 24 vac
should be found at terminal T2 on the SAT (pink wire). If
24 vac is not present, replace SAT.