Carrier 48TF004-007 specifications Durablade Economizer Troubleshooting, Ifc

Table 35 — Durablade Economizer Troubleshooting

		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 wir-
					ing (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 D18. If diode is not functioning properly, replace D18.
				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 econo-
					mizer 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 level. If
position.					the OAT or EC switches do not close, replace OAT or EC.
			Verify economizer control board	1.	Perform the following tests when OAT or EC is closed, Y1 is called for and
			is correctly wired and works		damper is at minimum position. Confirm 24 vac on gray terminal of the econ-
			properly.		omizer 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 close.			Incorrect wiring of economizer.	1.	Verify that SW2 and SW4 are wired and working properly (see unit label
					diagram.).
				2.	Check diode D19. If diode is not functioning properly, replace D19.
			Verify economizer control board	1.	After verifying that the wiring is correct, modulate the damper to the minimum
			is functioning properly.		position. Remove the calls for G.
				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, replace the economizer cir-
					cuit 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. 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 does			Verify that close-on-power-loss	1.	Check voltage potential across batteries. If lower than 14 vdc, replace close-
not close on power loss.			and economizer control board		on-power-loss power supply (9-v alkaline batteries). It is recommended that
			are functioning properly.		you check this emergency power supply 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 (Evaporator) Fan Contactor
IFO — Indoor (Evaporator) Fan On
OAT — Outdoor-Air Thermostat
PL	—	Plug
SAT — Supply-Air Thermostat
SW	—	Economizer Position Switch

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