M9/M11 Sterilizer High Limit Thermostat Error Codes: C980 to C987 Troubleshooting

WARNING

To prevent risk of shock always disconnect power before removing covers or performing any service procedure.

WARNING

Some procedures require power to be connected with covers removed. Line voltage is present. Use extreme caution to prevent electric shock.

An error code beginning with “C98” means the high-limit thermostat is tripped open. This is normally due to lack of water in the chamber.

C980

Display / Symptom	Cause	Check	Action
C980: POWER UP MODE HI-LIMIT OPEN UNPLUG / REPLUG UNIT High-limit thermostat opened for at least 0.25 seconds during POWER UP mode.	Maintenance not performed.	Verify weekly and monthly maintenance has been performed by customer. Refer to User Guide.	Perform monthly maintenance.
	Sterilizer was unplugged, then plugged back in while thermostat was still tripped.	Verify if error was preceded with other error codes. i.e. C983, C573	Unplug unit for 60 seconds, then plug unit into a dedicated, properly rated circuit. Allow unit to cool for 30 minutes.
	Hi Limit thermostat malfunctioning.	If error code does not reset Perform Thermostat Continuity Test Meter Reading - Anything but OL.	Replace thermostats.
	Loose / Damaged wire connection.	Check wire connections at high-limit thermostat and at J5 on Main PC Board.	Secure / Repair loose or damaged wire connections.
	If the unit skips the Fill mode…
	Tray rack / tray plate not installed properly.	Inspect tray rack / tray plate for proper installation. The 45 degree angled end of tray plate must be positioned upward and to the back of the chamber.	Install tray rack / tray plate properly.
	(M11) Mesh filter not in place.	Verify filter is in place.	Re-Install filter.
	Office running back to back cycles.	Check if operator is running consecutive cycles without completing the DRY cycle.	Complete full cycle.
	Water level sensor malfunctioning. Dirty/foreign object touching sensor.	Check sensor. Inspect water level sensor for foreign objects. burs, instruments, etc.	Clean/Dry water level sensor. Clean with Speed-Clean and scotch bright pad.. Remove foreign objects.
		Perform Water Level Sensor Test	Replace water level sensor.
	If the unit completes the Fill mode…
	Sterilizer is unlevel. Remove tray / trays	Verify support surface is level.	Place sterilizer on a level support surface.
	Sterilizer is unlevel. Remove tray / trays	Verify water on all sides of chamber are equal.	Place sterilizer on a level support surface.
	Pressure Leaks.	Check for loose / worn door and dam gaskets or water leaking around door. Verify door and dam gaskets are installed properly. Replace gasket kit 1x year.	Clean / Replace gaskets.
		Replacement fill / vent valve solenoid requires rectifier harness for DC coil.	Install rectifier harness.
		Check for voltage flow through rectifier harness. Refer to:Fill / Vent Valve Supply Voltage Test	Replace rectifier harness.
		Leaking or defective vent valve. Check for water leaking from condensing coil spout. Perform Vent Valve Test	Clean / Replace vent valve.
		Leaking or defective fill valve. Check for water leaking back into reservoir thru the fill line. Look for bubbles coming from bottom of reservoir. Perform Fill Valve Test	Clean / Replace fill valve.
		Leaking or defective air valve. Check for excessive steam coming thru condensing coil spout. During the HEAT and VENT modes, it is normal for steam to be exhausted thru the spout.	Clean / Replace air valve.
		Leaking or defective Pressure Relief Valve. Check for water / steam leakage from beneath the rear of the sterilizer. Perform Pressure Relief Valve Test	Replace pressure relief valve.
		Pressure transducer tubing leaking. Check for steam leakage at pressure transducer tubing connections.	Secure pressure transducer tubing connections with high temperature cable ties.
		Check all plumbing fitting connections for leakage.	Tighten or replace fittings.
	Heating element malfunctioning.	Inspect heating element. Heating element should lay flat in the bottom of the chamber. Heating element should be free of any flaking / pitting. Perform Heating Element Resistance Test (should read 9-11 Ω)	Replace heating element.
	PC Board malfunctioning.	Perform Heating Element Supply Voltage Test With harness attached to leads should have line voltage in test mode.	Replace Main PC board.
		Perform Main PC Board Relay Test. Check TP1 and TP2 for an acceptable range: 10 to 14 VDC.
		Perform Main PC Board Pressure Transducer Voltage Test. Acceptable range: 4.0 to 6.0 VDC.
	Sterilizer overloaded.	Check the size of the load. Refer to User Guide.	Reduce load size.

C981

Display / Symptom	Cause	Check	Action
C981: SELECT MODE HI-LIMIT OPEN UNPLUG / REPLUG UNIT High-limit thermostat opened for at least 0.25 seconds during SELECT mode.	Maintenance not performed.	Verify weekly and monthly maintenance has been performed by customer. Refer to User Guide.	Perform monthly maintenance.
	Sterilizer was unplugged, then plugged back in while thermostat was still tripped.	Verify if error was preceded by other error codes. (i.e. C983, C573)	Unplug unit for 60 seconds, then plug unit into a dedicated, properly rated circuit. Allow unit to cool for 30 minutes.
	Hi Limit thermostat malfunctioning.	If error code does not reset Perform Thermostat Continuity Test Meter Reading - Anything but OL	Replace thermostats
	Loose / Damaged wire connection.	Check wire connections at high-limit thermostat and at J5 on Main PC Board.	Secure / Repair loose or damaged wire connections.
	If the unit skips the Fill mode
	Tray rack / tray plate not installed properly.	Inspect tray rack / tray plate for proper installation. The 45 degree angled end of tray plate must be positioned upward and to the back of the chamber.	Install tray rack / tray plate properly.
	(M11) Mesh filter not in place.	Verify filter is in place.	Re-Install filter.
	Office running back to back cycles.	Check if operator is running consecutive cycles without completing the DRY cycle.	Complete full cycle.
	Water level sensor malfunctioning. Dirty/foreign object touching sensor.	Check sensor. Inspect water level sensor for foreign objects. burs, instruments, etc.	Clean/Dry water level sensor. Clean with Speed-Clean and scotch bright pad.. Remove foreign objects.
		Perform Water Level Sensor Test	Replace water level sensor.
	If the unit completes the Fill mode…
	Sterilizer is unlevel. Remove tray / trays.	Verify support surface is level.	Place sterilizer on a level support surface.
	Sterilizer is unlevel. Remove tray / trays.	Verify water on all sides of chamber are equal.	Place sterilizer on a level support surface.
	Pressure Leaks	Check for loose / worn door and dam gaskets or water leaking around door. Verify door and dam gaskets are installed properly. Replace gasket kit 1x year.	Clean / Replace gaskets.
		Replacement fill / vent valve solenoid requires rectifier harness for DC coil.	Install rectifier harness.
		Check for voltage flow through rectifier harness. Refer to:Fill / Vent Valve Supply Voltage Test	Replace rectifier harness.
		Leaking or defective vent valve. Check for water leaking from condensing coil spout. Perform Vent Valve Test	Clean / Replace vent valve.
		Leaking or defective fill valve. Check for water leaking back into reservoir thru the fill line. Look for bubbles coming from bottom of reservoir. Perform Fill Valve Test	Clean / Replace fill valve.
		Leaking or defective air valve. Check for excessive steam coming thru condensing coil spout. During the HEAT and VENT modes, it is normal for steam to be exhausted thru the spout.	Clean / Replace air valve.
		Leaking or defective Pressure Relief Valve. Check for water / steam leakage from beneath the rear of the sterilizer. Perform Pressure Relief Valve Test	Replace pressure relief valve.
		Pressure transducer tubing leaking. Check for steam leakage at pressure transducer tubing connections.	Secure pressure transducer tubing connections with high temperature cable ties.
		Check all plumbing fitting connections for leakage.	Tighten or replace fittings.
	Heating element malfunctioning.	Inspect heating element. Heating element should lay flat in the bottom of the chamber. Heating element should be free of any flaking / pitting. Perform Heating Element Resistance Test (should read 9-11 Ω)	Replace heating element.
	PC Board malfunctioning.	Perform Heating Element Supply Voltage Test With harness attached to leads should have line voltage in test mode.	Replace Main PC board.
		Perform Main PC Board Relay Test. Check TP1 and TP2 for an acceptable range: 10 to 14 VDC.
		Perform Main PC Board Pressure Transducer Voltage Test. Acceptable range: 4.0 to 6.0 VDC.
	Sterilizer overloaded.	Check the size of the load. Refer to User Guide	Reduce load size.

C982

Display / Symptom	Cause	Check	Action
C982: FILL MODE HI-LIMIT OPEN UNPLUG / REPLUG UNIT High-limit thermostat opened for at least 0.25 seconds during FILL mode.	Maintenance not performed.	Verify weekly and monthly maintenance has been performed by customer. Refer to User Guide.	Perform monthly maintenance.
	Sterilizer was unplugged, then plugged back in while thermostat was still tripped.	Verify if error was preceded with other error codes. i.e. C983, C573	Unplug unit for 60 seconds, then plug unit into a dedicated, properly rated circuit. Allow unit to cool for 30 minutes.
	Hi Limit thermostat malfunctioning.	If error code does not reset Perform Thermostat Continuity Test Meter Reading - Anything but OL	Replace thermostats.
	Loose / Damaged wire connection.	Check wire connections at high-limit thermostat and at J5 on Main PC Board.	Secure / Repair loose or damaged wire connections.
	If the unit skips the Fill mode…
	Tray rack / tray plate not installed properly.	Inspect tray rack / tray plate for proper installation. The 45 degree angled end of tray plate must be positioned upward and to the back of the chamber.	Install tray rack / tray plate properly.
	(M11) Mesh filter not in place.	Verify filter is in place.	Re-Install filter.
	Office running back to back cycles.	Check if operator is running consecutive cycles without completing the DRY cycle.	Complete full cycle.
	Water level sensor malfunctioning. Dirty/foreign object touching sensor.	Check sensor. Inspect water level sensor for foreign objects. (burs, instruments, etc.)	Clean/Dry water level sensor. Clean with Speed-Clean and scotch bright pad.. Remove foreign objects.
		Perform Water Level Sensor Test	Replace water level sensor.
	If the unit completes the Fill mode…
	Sterilizer is unlevel. Remove tray / trays	Verify support surface is level.	Place sterilizer on a level support surface.
	Sterilizer is unlevel. Remove tray / trays	Verify water on all sides of chamber are equal.	Place sterilizer on a level support surface.
	Pressure Leaks.	Check for loose / worn door and dam gaskets or water leaking around door. Verify door and dam gaskets are installed properly. Replace gasket kit 1x year.	Clean / Replace gaskets.
		Replacement fill / vent valve solenoid requires rectifier harness for DC coil.	Install rectifier harness.
		Check for voltage flow through rectifier harness. Refer to:Fill / Vent Valve Supply Voltage Test	Replace rectifier harness.
		Leaking or defective vent valve. Check for water leaking from condensing coil spout. Perform Vent Valve Test	Clean / Replace vent valve.
		Leaking or defective fill valve. Check for water leaking back into reservoir thru the fill line. Look for bubbles coming from bottom of reservoir. Perform Fill Valve Test	Clean / Replace fill valve.
		Leaking or defective air valve. Check for excessive steam coming thru condensing coil spout. During the HEAT and VENT modes, it is normal for steam to be exhausted thru the spout.	Clean / Replace air valve.
		Leaking or defective Pressure Relief Valve. Check for water / steam leakage from beneath the rear of the sterilizer. Perform Pressure Relief Valve Test	Replace pressure relief valve.
		Pressure transducer tubing leaking. Check for steam leakage at pressure transducer tubing connections.	Secure pressure transducer tubing connections with high temperature cable ties.
		Check all plumbing fitting connections for leakage.	Tighten or replace fittings.
	Heating element malfunctioning.	Inspect heating element. Heating element should lay flat in the bottom of the chamber. Heating element should be free of any flaking / pitting. Perform Heating Element Resistance Test (should read 9-11 Ω)	Replace heating element.
	PC Board malfunctioning.	Perform Heating Element Supply Voltage Test With harness attached to leads should have line voltage in test mode.	Replace Main PC board.
		Perform Main PC Board Relay Test. Check TP1 and TP2 for an acceptable range: 10 to 14 VDC.
		Perform Main PC Board Pressure Transducer Voltage Test. Acceptable range: 4.0 to 6.0 VDC.
	Sterilizer overloaded.	Check the size of the load. Refer to User Guide.	Reduce load size.

C983

Display / Symptom	Cause	Check	Action
C983: HEATUP MODE HI-LIMIT OPEN UNPLUG / REPLUG UNIT High-limit thermostat opened for at least 0.25 seconds during HEAT UP mode.	Maintenance not performed.	Verify weekly and monthly maintenance has been performed by customer. Refer to User Guide.	Perform monthly maintenance.
	High Limit Thermostats open.	If error code does not reset Perform Thermostat Continuity Test Meter Reading - Anything but OL	Replace thermostats.
	If the unit skips the Fill mode
	Tray rack / tray plate not installed properly.	Inspect tray rack / tray plate for proper installation. The 45 degree angled end of tray plate must be positioned upward and to the back of the chamber.	Install tray rack / tray plate properly.
	(M11) Mesh filter not in place.	Verify filter is in place.	Re-Install filter.
	Office running back to back cycles.	Check if operator is running consecutive cycles without completing the DRY cycle.	Complete full cycle.
	Water level sensor malfunctioning. Dirty/foreign object touching sensor.	Check sensor. Inspect water level sensor for foreign objects. (burs, instruments, etc.).	Clean/Dry water level sensor. Clean with Speed-Clean and scotch bright pad. Remove foreign objects.
		Perform Water Level Sensor Test	Replace water level sensor.
	If the unit completes the Fill mode
	Sterilizer is unlevel. Remove tray / trays.	Verify support surface is level.	Place sterilizer on a level support surface.
	Sterilizer is unlevel. Remove tray / trays.	Verify water on all sides of chamber are equal.	Place sterilizer on a level support surface.
	Pressure Leaks.	Check for loose / worn door and dam gaskets or water leaking around door. Verify door and dam gaskets are installed properly. Replace gasket kit 1x year.	Clean / Replace gaskets.
		Replacement fill / vent valve solenoid requires rectifier harness for DC coil.	Install rectifier harness.
		Check for voltage flow through rectifier harness. Refer to:Fill / Vent Valve Supply Voltage Test	Replace rectifier harness.
		Leaking or defective vent valve. Check for water leaking from condensing coil spout. Perform Vent Valve Test	Clean / Replace vent valve.
		Leaking or defective fill valve. Check for water leaking back into reservoir thru the fill line. Look for bubbles coming from bottom of reservoir. Perform Fill Valve Test	Clean / Replace fill valve.
		Leaking or defective air valve. Check for excessive steam coming thru condensing coil spout. During the HEAT and VENT modes, it is normal for steam to be exhausted thru the spout.	Clean / Replace air valve.
		Leaking or defective Pressure Relief Valve. Check for water / steam leakage from beneath the rear of the sterilizer. Perform Pressure Relief Valve Test	Replace pressure relief valve.
		Pressure transducer tubing leaking. Check for steam leakage at pressure transducer tubing connections.	Secure pressure transducer tubing connections with high temperature cable ties.
		Check all plumbing fitting connections for leakage.	Tighten or replace fittings.
	Heating element malfunctioning.	Inspect heating element. Heating element should lay flat in the bottom of the chamber. Heating element should be free of any flaking / pitting. Perform Heating Element Resistance Test (should read 9-11 Ω)	Replace heating element.
	PC Board malfunctioning.	Perform Heating Element Supply Voltage Test With harness attached to leads should have line voltage in test mode.	Replace Main PC board.
		Perform Main PC Board Relay Test. Check TP1 and TP2 for an acceptable range: 10 to 14 VDC.
		Perform Main PC Board Pressure Transducer Voltage Test. Acceptable range: 4.0 to 6.0 VDC.
	Sterilizer overloaded.	Check the size of the load. Refer to User Guide.	Reduce load size.

C984

Display / Symptom	Cause	Check	Action
C984: STERILIZE MODE HI-LIMIT OPEN UNPLUG / REPLUG UNIT High-limit thermostat opened for at least 0.25 seconds during STERILIZE mode.	Maintenance not performed.	Verify weekly and monthly maintenance has been performed by customer. Refer to User Guide.	Perform monthly maintenance.
	High Limit Thermostats open.	Verify if unit still overheated.	Unplug unit for 60 seconds, then plug unit into a dedicated, properly rated circuit. Allow unit to cool for 30 minutes.
	Hi Limit thermostat malfunctioning.	If error code does not reset… Perform Thermostat Continuity Test Meter Reading - Anything but OL	Replace thermostats.
	Loose / Damaged wire connection.	Check wire connections at high-limit thermostat and at J5 on Main PC Board.	Secure / Repair loose or damaged wire connections.
	Pressure Leaks.	Check for loose / worn door and dam gaskets or water leaking around door. Verify door and dam gaskets are installed properly. Replace gasket kit 1x year.	Clean / Replace gaskets.
		Replacement fill / vent valve solenoid requires rectifier harness for DC coil.	Install rectifier harness.
		Check for voltage flow through rectifier harness. Refer to:Fill / Vent Valve Supply Voltage Test	Replace rectifier harness.
		Leaking or defective vent valve. Check for water leaking from condensing coil spout. Perform Vent Valve Test	Clean / Replace vent valve.
		Leaking or defective fill valve. Check for water leaking back into reservoir thru the fill line. Look for bubbles coming from bottom of reservoir. Perform Fill Valve Test	Clean / Replace fill valve.
		Leaking or defective air valve. Check for excessive steam coming thru condensing coil spout. During the HEAT and VENT modes, it is normal for steam to be exhausted thru the spout.	Clean / Replace air valve.
		Leaking or defective Pressure Relief Valve. Check for water / steam leakage from beneath the rear of the sterilizer. Perform Pressure Relief Valve Test	Replace pressure relief valve.
		Pressure transducer tubing leaking. Check for steam leakage at pressure transducer tubing connections.	Secure pressure transducer tubing connections with high temperature cable ties.
		Check all plumbing fitting connections for leakage.	Tighten or replace fittings.
	Heating element malfunctioning.	Inspect heating element. Heating element should lay flat in the bottom of the chamber. Heating element should be free of any flaking / pitting. Perform Heating Element Resistance Test (should read 9-11 Ω)	Replace heating element.
	Sterilizer is unlevel. Remove tray / trays.	Verify support surface is level.	Place sterilizer on a level support surface.
	Sterilizer is unlevel. Remove tray / trays.	Verify water on all sides of chamber are equal.	Place sterilizer on a level support surface.
	PC Board malfunctioning.	Perform Heating Element Supply Voltage Test With harness attached to leads should have line voltage in test mode.	Replace Main PC board.
		Perform Main PC Board Relay Test. Check TP1 and TP2 for an acceptable range: 10 to 14 VDC.
		Perform Main PC Board Pressure Transducer Voltage Test. Acceptable range: 4.0 to 6.0 VDC.
	Sterilizer overloaded.	Check the size of the load. Refer to User Guide.	Reduce load size.

C985

Display / Symptom	Cause	Check	Action
C985: VENT MODE HI-LIMIT OPEN UNPLUG / REPLUG UNIT High-limit thermostat opened for at least 0.25 seconds during VENT mode.	Hi Limit thermostat malfunctioning.	If error code does not reset Perform Thermostat Continuity Test Meter Reading - Anything but OL	Replace thermostats.
	Loose / Damaged wire connection.	Check wire connections at high-limit thermostat and at J5 on Main PC Board.	Secure / Repair loose or damaged wire connections.
	Pressure Leaks.	Check for loose / worn door and dam gaskets or water leaking around door. Verify door and dam gaskets are installed properly. Replace gasket kit 1x year.	Clean / Replace gaskets.
		Replacement fill / vent valve solenoid requires rectifier harness for DC coil.	Install rectifier harness.
		Check for voltage flow through rectifier harness. Refer to:Fill / Vent Valve Supply Voltage Test	Replace rectifier harness.
		Leaking or defective vent valve. Check for water leaking from condensing coil spout. Perform Vent Valve Test	Clean / Replace vent valve.
		Leaking or defective fill valve. Check for water leaking back into reservoir thru the fill line. Look for bubbles coming from bottom of reservoir. Perform Fill Valve Test	Clean / Replace fill valve.
		Leaking or defective air valve. Check for excessive steam coming thru condensing coil spout. During the HEAT and VENT modes, it is normal for steam to be exhausted thru the spout.	Clean / Replace air valve.
		Leaking or defective Pressure Relief Valve. Check for water / steam leakage from beneath the rear of the sterilizer. Perform Pressure Relief Valve Test	Replace pressure relief valve.
		Pressure transducer tubing leaking. Check for steam leakage at pressure transducer tubing connections.	Secure pressure transducer tubing connections with high temperature cable ties.
		Check all plumbing fitting connections for leakage.	Tighten or replace fittings.
	Heating element malfunctioning.	Inspect heating element. Heating element should lay flat in the bottom of the chamber. Heating element should be free of any flaking / pitting. Perform Heating Element Resistance Test (should read 9-11 Ω)	Replace heating element.
	Sterilizer is unlevel. Remove tray / trays .	Verify support surface is level.	Place sterilizer on a level support surface.
	Sterilizer is unlevel. Remove tray / trays .	Verify water on all sides of chamber are equal.	Place sterilizer on a level support surface.
	PC Board malfunctioning.	Perform Heating Element Supply Voltage Test With harness attached to leads should have line voltage in test mode.	Replace Main PC board.
		Perform Main PC Board Relay Test. Check TP1 and TP2 for an acceptable range: 10 to 14 VDC.
		Perform Main PC Board Pressure Transducer Voltage Test. Acceptable range: 4.0 to 6.0 VDC.
	Sterilizer overloaded.	Check the size of the load. Refer to User Guide.	Reduce load size.

C987

Display / Symptom	Cause	Check	Action
C987: DRY MODE HI-LIMIT OPEN UNPLUG / REPLUG UNIT High-limit thermostat opened for at least 0.25 seconds during DRY mode.	High Limit Thermostats open.	Verify if unit still overheated.	Unplug unit for 60 seconds, then plug unit into a dedicated, properly rated circuit. Allow unit to cool for 30 minutes.
	Temperature sensor malfunctioning.	Check for residue build up on temperature sensor probe.	Clean sensor probe with Speed-Clean, distilled water, and abrasive pad.
		Check that nothing is touching or crowding the temperature sensor. Example: trays, pouches, cassettes, etc.	Reposition items so nothing touches or crowds the temperature sensor.
		Perform Temperature Sensor Resistance Test. Allow sensor to cool to room temperature before testing. Acceptable range 1.07-1.1K Ω. Refer to: Temperature Sensor Resistance Test	Replace temperature sensor.
		Perform Temperature Sensor Supply Voltage Test. Disconnect sensor harness from J12 on PC board. On pins 1 and 2 acceptable range is 4.0 - 6.0 VDC. Refer to: Temperature Sensor Supply Voltage Test	Replace Main PC board.
	Hi Limit thermostat malfunctioning.	If error code does not reset Perform Thermostat Continuity Test Meter Reading - Anything but OL	Replace thermostats.
	Loose / Damaged wire connection.	Check wire connections at high-limit thermostat and at J5 on Main PC board.	Secure / Repair loose or damaged wire connections.
	Door spring missing / damaged.	If the door motor releases the latch, but the door remains closed, Inspect door spring for damage.	Replace door springs.
		Verify if door is at the vented position. Push in on door with out lifting handle.
		Verify the QTY of door springs. M11- QTY 2, M9-QTY 1
		Verify door springs are at a 45 degree angle.	Place door spring at a 45 degree angle.
	Door hinge binding.	Check for binding or build up of debris in the door hinges.	Clean debris from hinges.
	Facility voltage too high / low.	Test facility supply voltage. Voltage must be 115V models: 104 - 127 VAC 50/60 Hz 230V models: 207 - 253 VAC 50/60 Hz	Contact an electrician to modify voltage.
	Heating element malfunctioning.	Inspect heating element. Heating element should lay flat in the bottom of the chamber. Heating element should be free of any flaking / pitting. Perform Heating Element Resistance Test (should read 9-11 Ω)	Replace heating element.
	PC Board malfunctioning.	Perform Heating Element Supply Voltage Test With harness attached to leads should have line voltage in test mode.	Replace Main PC board.

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M9/M11 Sterilizer High Limit Thermostat Error Codes: C980 to C987 Troubleshooting