Carrier 39L specifications Unit Troubleshooting, Problem Possible Cause Corrective Action

UNIT TROUBLESHOOTING

PROBLEM	POSSIBLE CAUSE	CORRECTIVE ACTION
	PIC control is OFF	Check for correct power or blown fuses (F2).
		Correct any de®ciencies.
		Check LEDs on control module (PSIO). If LED is not solidly
	Faulty connections	illuminated, check for loose connections. If all wires and
		connectors are secure, replace PSIO module as described
		on page 112.
	PIC control has incorrect time	Verify control shows correct time. If incorrect, enter correct
		time.
	Supply fan HOA switch in OFF position	Verify HOA switch is in the AUTO position.
		Check low-temperature thermostat and high-pressure switch
Unit does not run	Safety controls are tripped
		(VAV units only). Reset switches if necessary.
	PIC control left in Quick Test	Using the local interface device, exit Quick Test.
	(Display shows Mode 38)	Press 5 TEST, and then ENTR to exit.
	Unit is con®gured for and is currently	Verify that unit should be in the Demand Limit mode. If not,
		cycle power to PIC to release unit from Demand Limit
	in Demand Limit Mode (CV units only)
		mode.
	Unit is in Smoke Evacuation or Fire Shut-	Verify that unit should be in one of these modes. If not,
	down mode (Display shows 35 or 37)	check for shorted input on Fire Shutdown or Evacuation.
	Minimum inverter set point too low	Adjust minimum to 20% at 4 mA signal and 100% at 20 mA
	(VAV units only)	signal.
		Check status of SFS (4 STAT). If SFS is OFF, check supply
	No fan status	fan status switch for proper operation. Switch must be ON
		for heat coil to function properly.
	Heat coil valve (HCV) is forced closed	Check status of HCV (5 STAT). If HCV is forced, remove
		force and check operation.
	NO hot water or steam available,	Check source and correct any problems found.
	no power if electric heat
	Electric heater safety tripped	Reset heater safety. Check for proper operation.
		Check for blown fuse (F6). Replace if necessary. If fuse
No heat	No power to valve	is intact, check for proper connections. Check transformer
		output.
		Check for blown fuse (F5). Replace if necessary. If fuse
	No power to electric heater control	is intact, check for proper connections. Check transformer
		output.
	Incorrect reading from space temperature sensor,	Check status of sensor readings for accuracy.
	supply-air temperature sensor, or return-air
		Replace sensor if defective.
	temperature sensor (VAV units)
		Check con®guration for proper heating set point and
	Con®guration error	Submaster Gain (SMG). An improper SMG can cause the
		heating valve to be held closed.
	Heat coil valve (HCV) is forced open	Check status of HCV (5 STAT). If HCV is forced, remove
		force and check operation.
	Incorrect reading from space temperature sensor,	Check status of sensor readings for accuracy. Replace
Overheating	supply-air temperature sensor, or return-air
		sensor if defective.
	temperature sensor (VAV units)
		Check con®guration for proper heating set point and
	Con®guration error	Submaster Gain (SMG). An improper SMG can cause the
		heating valve to be held open.
		Check status of SFS (4 STAT). If status is OFF, check
	No fan status	switch for proper operation. Supply fan status switch must
		be ON for cooling coil to function properly.
	Cooling coil valve (CCV) is forced closed	Check status of CCV (5 STAT). If CCV is forced, remove
		force and check operation.
	No chilled water available	Check source of chilled water. Correct any problems found.
No cooling		Check for blown fuse (F3). Replace if necessary. If fuse
	No power to cooling coil valve	is intact, check for proper connections. Check transformer
		output.
	Incorrect reading from space temperature sensor,	Check status of sensor readings for accuracy. Replace
	supply-air temperature sensor, or return-air
		sensor if defective.
	temperature sensor (VAV units)
		Check con®guration for proper cooling set point and
	Con®guration error	Submaster Gain (SMG). An improper SMG can cause the
		CCV to be held closed.
	Cooling coil valve (CCV) is forced open	Check status of CCV (5 STAT). If CCV is forced, remove
		force and check operation.
	Incorrect reading from space temperature sensor,	Check status of sensor readings for accuracy. Replace
Overcooling	supply-air temperature sensor, or return-air
		sensor if defective.
	temperature sensor (VAV units)
		Check con®guration for proper cooling set point and
	Con®guration error	Submaster Gain (SMG). An improper SMG can cause the
		CCV to be held open.
LEGEND
CV Ð Constant Volume
VAV Ð Variable Air Volume

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