Bryant 548D installation instructions Durablade Economizer Troubleshooting, Ifc, Ifo, Oat, Sat

Table 15 — Durablade Economizer Troubleshooting

	PROBLEM	CAUSE		REMEDY
Damper does not		Indoor fan is off.	1.	Check to ensure that 24 vac is present at terminal C1 on the IFC or that 24 vac is
open.				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 connection board.
		No power to economizer	1.	Check that SW3 is properly making contact with the damper blade. Check that
		motor.		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 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, replace the
			motor.
Economizer operation		OAT or EC set too high.	1.	Set at correct temperature (3 F below indoor space temperature).
limited to minimum			2.	Check OAT or EC by setting above outdoor temperature or humidity level. If the
position.				OAT or EC switches do not close, replace OAT or EC.
		Economizer control board	1.	Perform the following tests when OAT or EC is closed. Y1 is called for, and damper
		incorrectly wired or not		is at minimum position. Confirm 24 vac on gray terminal of the economizer control
		functioning.		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 working 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.
		Incorrect SAT wiring or	1.	After verifying that the OAT and EC settings and the economizer control board wir-
		inoperative SAT.		ing 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 functioning and wired properly and
				no 24 vac exists, check wiring (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.
Damper does not		Incorrect economizer	1.	Verify that SW2 and SW4 are wired and working properly (see unit label diagram).
close.		wiring.	2.	Check diode D19. If diode is not functioning properly, replace economizer control board.
		Incorrect damper actuator	1.	After verifying that the wiring is correct, modulate the damper to the minimum posi-
		wiring or inoperative		tion. Remove the calls for G.
		economizer circuit board.	2.	If the damper does not move, check for 24 vac at PL6-1 (red wire). If 24 vac is not
				present, check wiring (see unit label diagram).
			3.	If damper still does not move, check for 24 vac at blue terminal of economizer con-
				trol board (blue wire). If 24 vac is not present, replace the economizer control board.
		Incorrect SAT wiring or	1.	After verifying that the wiring is correct and the economizer control board is func-
		inoperative SAT.		tioning properly, place the OAT or EC switch in the closed position. Place a call for
				Y1 and open the damper to the fully open position. Confirm that the 24 vac terminal
				of the SAT has 24 vac (white wire). If 24 vac is not present, check wiring (see unit
				label diagram).
			2.	If supply-air temperature is less than 52 F, 24 vac should be found at terminal T1
				on the SAT (violet wire). If 24 vac not found, replace SAT.
		Economizer motor failure.	If economizer control board and SAT are functioning properly, verify that there is a
			minimum of 18 vdc at the positive motor terminal. If a minimum of 18 vdc is present
			and the motor is still not operating, replace the motor.
Economizer damper		Insufficient battery power,	1.	Check voltage potential across batteries. If lower than 14 vdc, replace close-on-
does not close on		inoperative economizer		power-loss power supply (9-v alkaline batteries). Check this emergency power sup-
power loss.		control board.		ply on a regular basis or whenever the filters are changed.
			2.	If the close-on-power-loss and economizer control board are functioning properly,
				check for 14 vdc or higher at the blue terminal of the economizer control board
				(blue wire) when power is disconnected from unit. If 14 vdc is not present, replace
				the control board.
	LEGEND
C1	— Common Power
EC	— Enthalpy Control
IFC	— Indoor Fan Contactor
IFO	— Indoor Fan On
OAT	— Outdoor-Air Thermostat
PL	— Plug
SAT	— Supply-Air Thermostat
SW	— Economizer Position Switch

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