Carrier Complete Troubleshooting for Air Conditioner Economizers

Table 18 Ð Durablade Economizer Troubleshooting

	PROBLEM	CAUSE		REMEDY
Damper does not		Indoor (evaporator) fan is off.	1.	Check to ensure that 24 vac is present at terminal C1 on the IFC or
open.				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 connection 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 D1. If diode is not functioning properly, replace D1.
			3.	Con®rm 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 dia-
				gram). If 24 vac is found in both places, check for 24 vac at the yel-
				low 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, 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
position.				level. If the OAT or EC switches do not close, replace OAT or EC.
		Verify economizer control board is correctly wired	1.	Perform the following tests when OAT or EC is closed, Y1 is called
		and works properly.		for and damper is at minimum position. Con®rm 24 vac on gray ter-
				minal of the economizer control 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.
		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 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 wiring of economizer.	1.	Verify that SW2 and SW4 are wired and working properly (see unit
close.				label diagram).
			2.	Check diode D2. If diode is not functioning properly, replace D2.
		Verify economizer control board is functioning	1.	After verifying that the wiring is correct, modulate the damper to the
		properly.		minimum position. Remove the call for G (evaporator fan).
			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 control board (blue wire). If 24 vac is not present, re-
				place the economizer circuit board.
		Check SAT.	1.	After verifying that the wiring is correct and the economizer control
				board is functioning 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. Con®rm 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 if 18 vdc is present and the motor is still not operating, re-
			place the motor.
Economizer damper		Verify that close-on-power-loss and economizer	1.	Check voltage potential across batteries. If lower than 14 vdc, re-
does not close on		control board are functioning properly.		place close-on-power-loss power supply (9-v alkaline batteries). It is
power loss.				recommended that you check this emergency power supply on a
				regular basis or whenever the ®lters are changed.
			2.	If the close-on-power-loss and economizer control board are func-
				tioning properly, check for 14 vdc or higher at the blue terminal of
				the economizer control board (blue wire) when power is discon-
				nected from unit. If 14 vdc is not present, replace the control board.
	LEGEND
C1	Ð Common Power
EC	Ð Enthalpy Control
IFC	Ð Indoor (Evaporator) Fan Contactor
IFO	Ð Indoor (Evaporator) Fan On
OAT	Ð Outdoor-Air Thermostat
PL	Ð Plug
SAT	Ð Supply-Air Thermostat
SW	Ð Economizer Position Switch

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