Low Heat Fail

 

ERROR MESSAGE/ISSUE/SYMPTOMS:

• Low Heat- this message occurs if the temperature does not reach the sterilization temperature set point after running for 50 minutes. 

REALTED MODELS:

• All E, EK, EA, EKA, EZ, EZ10K Models

WHO CAN SOLVE: 

• End user and sales rep- limited
• Technician

CAUSE(S):

• Chamber is overloaded
• Air Jet is clogged
• Improper line voltage
• Air Outlet valve is stuck closed
• Faulty heating elements
• Faulty solid state relay (SSR) for heating elements
• Calibration
• Faulty pressure transducer
• Faulty temperature sensor
• Faulty ajunc3 board
• Faulty Digital Predg Board

LEVEL OF TROUBLESHOOTING:

End User Level

Chamber is overloaded

• Ensure that the unit is not being overloaded, if the unit fails with Low Heat try running the cycle again with 1/2 of your typical instrument load and see if it completes the cycle. If it does complete you may be overloading the chamber. The chambers can only handle so much weight inside the chamber before it will start to have an issue (img.61 and img.62) 

  

  img.61- max load.1

  

  img.62- max load.2

  Air Jet is clogged

  *Always use caution when performing this maintenance, steam and metal will be hot, keep your hand a safe distance away from the reservoir opening*

• Locate the Air Jet Valve inside the water reservoir (img.63)

  

  img.63- air jet

• As the unit is running a cycle take a pen/pencil/screwdriver (anything small enough to fit in the loop and keep your hand out of the reservoir tank) and insert it into the loop from the air jet wire pin.
• Using the loop, pull the air jet pin out and push the air jet pin in, repeat this about 10-12 times. The air jet should start making a hissing sound and steam should start escaping from it. 
• If the above attempts do not resolve the issue, a technician will be needed to troubleshoot further

Technician Level

• Ensure all User Level troubleshooting steps above has been 

Improper Line Voltage

• It is recommended for all units to be installed on their own dedicated circuits. If the unit is not on its own dedicated circuit other electronics may be running and affecting the power going to the autoclave
• If the unit does not have proper power supplying the unit, the unit could take too long to heat and fail for low heat  

• Check the voltage either from the outlet or through the unit's power cord to verify that the unit is getting the proper voltage (img.64 and img.65)

  img.64- elec.1

img.65- elec.2

• If the office's electric is causing the issue, they should contact an electrician to address the issue. If the electric is not causing the issue proceed to the next step
• Unplug the unit and remove the covers
• Inspect the units power cord for any signs of burning/melting. If needed replace the power cord
• Inspect the units power socket for any signs of burning/melting. If needed replace the power socket

• Inspect all the units wiring and components (img.66) in the rear of the unit for any signs of burning/melting. if needed replace the wiring. From the back of the unit the wires run to the front and pass through the 12 pin molex connector

  

  img.66- back panel

• Inspect the wiring in the square 12 pin molex connector for any signs of burning/melting (img.67, img.68, img.69). If needed replace the molex and/or the wiring

  

  img.67- 12 pin.3

  

  img.68- 12 pin.4

  

  img.69- 12 pin.5

• Inspect the units front on/off rocker switch for any signs of burning/melting (img.70). If needed replace the on/off rocker and/or wiring

img.70- on/off

NOTE- Unit must be plugged in to check the voltage readings

• Disconnect the wires to the on/off rocker switch take an AC voltage reading at the on/off rocker. The top (single wires) wires to the switch are your incoming voltage, you can across the wires for the reading. The reading should be the line voltage (same as the wall voltage). If the unit is not getting line voltage to the top (single wires) at the on/off switch, the unit is losing voltage. Work your way back (12 pin molex- temperature safety cut-out- circuit breaker- power socket- power cord) and check the AC voltages to see where the voltage drop is coming from. Replace the necessary part and/or wiring.
• Unplug the unit and reconnect the single wires, leave the bottom 2 wire connections (double wires are the output voltage) disconnected. Plug the unit back in and power it on, carefully take a voltage reading at the 2 terminals (use caution, live voltage will be at the terminals) without the wires connected to verify the same line voltage is coming out from the switch. If the voltage is not the same, replace the on/off rocker. If the voltage is the same proceed to the next step. 

Testing the heating elements 

• Unplug the unit and remove the covers
• Remove the insulation blanket from around the chamber 

• Take an ohm reading on the terminals for the heating element, the chart below shows the proper readings. If the readings are incorrect replace the heating elements. (img.15 and img.16)

  

  img.15- ohm and amp

  

  img.16- heaters.1

• Take an ohm reading from the heating elements to ground. If the meter reads O/L there is no short to ground in the heating elements and proceed to the next step. If the meter reads anything other than O/L there is a short to ground in the heating elements and all of the heating elements need to be replaced.  (img.17)

  

  img.17- heaters.2

Testing the Solid State Relay (SSR)

• Unplug the unit and remove the covers

• Label and remove the wiring from the SSR. The SSR for the heating element is located below the ajunc3 board. (img.18 and img.19)

  

  img.18- ssr.1

• SSR with plastic cover removed, terminals 3 & 4- input- 5VDC, terminals 1 & 2- output- Line voltage AC (img.19)

  

  img.19- ssr.2

• Check for a short circuit between terminals 3 & 4, 1 & 2, 3 & 1, 4 & 2, 3 & 2, 4 & 1. Make sure there are no direct shorts. If a direct short is found in the SSR, replace it. If the meter reads O/L proceed to the next step.
• Check for an open between terminals 1 & 2. Be sure to reverse the meter leads and check in the opposite direction. Repeat the procedure for terminals 3 & 4. If an open (O/L) is found, replace the SSR. If the meter does need read O/L, proceed to the next step

• Reconnect the wires to the four connectors of the SSR

  Testing the SSR- terminals 3 and 4

• Ensure that dip switch #4 on the back of the Digital Predg board is off (down position), if the #4 dip switch is on (up) turn it off prior to proceeding (the #4 dip switch is normally off for 120v units and normally on for 230v units). Dip switch #4 is a preheat function, if it is on the heaters will heat once the unit is powered on (img.20). We need the heaters to be off for the next step.

  

  img.20- dip sw

• Plug the unit back in and power it on, ensure that the unit is sitting idle not running a cycle. 
• Take a DC voltage reading from terminal 3 on the SSR to ground, there should be a voltage reading between 3.5v and 5v DC. Afterwards take a DC voltage reading from terminal 4 on the SSR to ground, there should be a voltage reading between 3.5v and 5v DC. A good reading indicates that the SSR is not turned on. 
• If terminal 3 reads properly skip the below testing the power supply section. If terminal 3 does not read between 3.5v and 5v DC, check the power supply to ensure that it is providing the proper voltage. The power supply (circled blue below) is mounted above the ajunc3 board. Unplug the unit and disconnect the output connection from the ajunc3 board (circled white below). (img.21)

 

 

Testing the Power Supply

img.21- power supply.1

• Plug the unit back in and power it on, take a DC volt reading between the red and black wires. A good reading is 12v DC. (img.22)

  

  img.22- power supply.2

• Take a DC volt reading between the orange and black wires. A good reading is 5v DC. If the power supply is not reading 5v and 12v DC, replace the power supply. If the readings are correct proceed to the next step to continue testing the SSR. 

  

  img.23- power supply.3

  Testing the SSR- terminals 3 and 4 continued

• If terminal 4 reads correctly skip this next step. If terminal 4 does not read the correct voltage, unplug the unit and remove the wire on terminal 4. Turn the power back on and take a DC voltage reading from terminal 4 on the SSR to ground, there should be a voltage reading between 3.5v and 5v DC. If the reading is still not correct, replace the SSR. If the reading is correct, proceed to the next step

• If the reading is correct, check continuity between the terminal #4 wire and the appropriate connector; unplug the unit when taking this reading. JP4 is the connection for checking the Heater SSR. (img.24 and img.25)

  

  img.24- ssr.3                                                                                                                                     img.25- ssr.4

• If there is no continuity replace the wiring. If there is continuity and the terminal 4 reading is still incorrect the unit has a control problem, replace the Digital Predg board. 

  Testing the SSR terminals 1 and 2 for 110v units

• Turn the unit on and ensure the dip switch #4 is still off, the heaters must be off for this next step. 
• Terminal 2 of the SSR should read between 110v and 125v AC to ground. Terminal 1 should read near 0 volts AC to ground. Reading across terminals 1 & 2 should show between 110 and 125 volts.
• If terminal 2 does not read between 110 and 125 volts to ground, there is a problem with the line voltage wiring going to the SSR. 
• If terminal 1 shows the same voltage as terminal 2, replace the SSR. If there is a voltage reading less than 100 volts across terminals 1 & 2, replace the SSR.

• Power the unit off so we can enter the in/out test on the unit so we can energize the heaters, this next step must be done with the heaters on. Prior to powering the unit on press and hold the up arrow on the keypad. Continue holding up as you power the unit on. Once the screen comes on release the up button. Press and release the up button to advance to the next step in the in/out test, stop pressing up once the screen displays Heaters. If you accidentally advance past the Heaters option, power the unit off and repeat the steps. 

  In/Out Test menu order

   

  img.26- in/out test

• Terminals 1 and 2 should each read between 110 and 125 volts to ground. If terminal 2 does not show between 110 and 125 volts to ground, there is a problem with the line voltage wiring to the SSR. If terminal 1 does not show between 110 and 125 volts to ground, replace the SSR.
• Reading across terminals 1 and 2 should show close to 0 volts. If the reading across terminals 1 & 2 is greater than 1 or 2 volts, replace the SSR

Testing the SSR terminals 1 and 2 for 230v units

• Turn the unit on and ensure the dip switch #4 is still off, the heaters must be off for this next step. 
• Terminal 1 of the SSR should read between 110v and 125v AC to ground. Terminal 2 of the SSR should read between 110v and 125v AC to ground. If terminals 1 and 2 do not each read approximately 110 volts to ground, there is a problem with the line voltage wiring going to the SSR.
• A reading across terminals 1 & 2 should show between 220 and 235 volts. If a voltage of between 220 and 235 volts is not present across terminals 1 & 2, unplug the unit and remove the wires. 
• Plug the unit back in and carefully take a reading across the wires. If a voltage between 220 and 235 is present across the unconnected wires, the SSR needs to be replaced. If the voltage is still incorrect, the problem is with the line voltage wiring going to the SSR.

• Power the unit off so we can enter the in/out test on the unit so we can energize the heaters, this next step must be done with the heaters on. Prior to powering the unit on press and hold the up arrow on the keypad. Continue holding up as you power the unit on. Once the screen comes on release the up button. Press and release the up button to advance to the next step in the in/out test, stop pressing up once the screen displays Heaters. If you accidentally advance past the Heaters option, power the unit off and repeat the steps. 

  In/Out Test menu order

   

  img.26- in/out test

• Terminal 1 of the SSR should read between 110v and 125v AC to ground. Terminal 2 of the SSR should read between 110v and 125v AC to ground. If terminals 1 and 2 do not each read approximately 110 volts to ground, there is a problem with the line voltage wiring going to the SSR.
• A reading across terminals 1 & 2 should show a voltage near 0 volts AC. If the voltage reading across terminals 1 and 2 is higher than 5 volts, replace the SSR.
• If the SSR tests properly proceed to the next step

Troubleshooting air outlet solenoid mechanical issue

• Check the air outlet solenoid (img.49), it may not be labeled with 41 like in the photo below, on the back of the reservoir for cracks and/or debris as well by opening the solenoid valve. Inspect the plunger to ensure that it can move freely (img.47 and img.48). This solenoid valve is supposed to be open at the start of the cycle until the unit reaches 194°F, it will then close and remain closed. It will open again during the end of the exhaust phase and remain open throughout the entire dry cycle. If the air outlet valve is stuck closed the unit will build pressure faster than it will build temperature which can cause the heaters to turn off and fail for low heat. 

img.49- sol.3

img.47- sol.1

img.48- sol.3

• If the solenoid is dirty or has debris clean it and try running another cycle. If the valve continues to leak or the valve is cracked, and/or no debris is found replace the solenoid.

Solenoid Valve Electrical Issue- Valve does not energize

• Power the unit on but do not start a cycle
• Locate the air outlet valve

• Air valve- should be energized sitting idle when the door is closed, should not be energized when sitting idle and the door is open. Close the door and feel for magnetism at the coil (img.52). If the coil is not energized (no magnetism) continue with troubleshooting the electrical solenoid valve issue. If the coil is energized with the door closed proceed to the next section of troubleshooting (calibration issue).

  

  img.52- sol.4

• If the solenoid is not energized, unplug the unit and remove the solenoid valve coil from the plunger, remove the Phillips head screw from the coil and unplug the coil from the wire harness. Once the coil is unplugged take an ohm reading at the coil to ensure the coil is functioning. 

  Note: The coil will either be 12vdc 10w or 12vdc 12w, the ohm reading would be different between the two coils, the coil would be labeled.

  

img.53- sol.5

• If the solenoid coil reads correctly check the wiring at the back of the ajunc3 board, ensure that the wiring is intact, has a good connection, and no corrosion is found. Address any wiring issue if needed, if the wiring is not causing the issue, reconnect the connector and proceed to the next step.

  

  img.6- ajunc3 12 pin.1

  Testing signal to valve with test point board

• Prior to powering the unit on press and hold the up arrow on the keypad. Continue holding up as you power the unit on. Once the screen comes on release the up button, the unit will now be in the in/out test. Press and release the up button to advance to the next step in the in/out test, stop pressing up once the screen displays Air V. If you accidentally advance past the Air V option, power the unit off and repeat these steps. 

  In/Out Test menu order

  

img.26- in/out test

• With the air outlet valve energized (Air V on the display) connect the test point board (part of the TEST-9 calibration kit) to the ajunc3 board. Connect your positive lead of the meter to TP 14 and connect your negative lead to TP 1. With the valve energized you should read between 0v and 1v DC. When the valve is not energized you should read between 3.5v and 5v DC.  

  

img.71- tp.1

img.72- tp.2

img.73- tp.3

img.74- tp.4

img.75- tp.5

img.76- tp.6

img.77- tp.7

Testing signal to valve without the test point board

• If you do not have the test point board you can check the voltage reading going to the coil. The only downside to checking it this way is there is no way to test if the Digital Predg board is causing the issue or if it is the ajunc3 board causing the issue. 
• Unplug the unit and remove the solenoid valve coil from the plunger, remove the Phillips head screw from the coil and unplug the coil from the wire harness. (img.78)

• On the wire harness side of the coil, remove the rubber gasket and use a small flat head screwdriver to expose the wiring (img.79 and img.80)

  

  img.78- sol.6

  

  img.79- sol.7

  

  img.80- sol.8

• Next, we need to energize the coil in the in/out test

• Prior to powering the unit on press and hold the up arrow on the keypad. Continue holding up as you power the unit on. Once the screen comes on release the up button, the unit will now be in the in/out test. Press and release the up button to advance to the next step in the in/out test, stop pressing up once the screen displays Air V. If you accidentally advance past the Air V option, power the unit off and repeat these steps. 

  In/Out Test menu order

  

  img.26- in/out test

• With the air outlet valve energized (Air V on the display) take a DC volt reading at the wire connections. You should have a reading of about 12V DC at the coil. If you receive the correct reading but the valve still does not open either the coil is defective or there is a mechanical issue with the plunger. 
• If you do not receive the correct reading replace the ajunc3 board and calibrate the new board. If the issue persists after replacing the ajunc3 board, replace the Digital Predg board.

Calibration

If the Air Outlet Solenoid Valve is not the problem but the pressure reading is still too high causing the failure the issue is most likely calibration. Calibration would require the Tuttnauer TEST-9 calibration kit. 

img.29- cal.1

img.30- cal.2

img.31- cal.3

img.32- cal.4

img.33- cal.5

img.34- cal.6

img.35- cal.7

img.36- cal.8

img.37- cal.9

img.38- cal.10

• If only the pot 2 adjustment cannot be made replace the pressure transducer. If the issue persists with a new pressure transducer replace the ajunc3 board. 
• If pot 4 and/or pot 5 cannot be calibrated to the proper range replace the ajunc3 board. 

• If the calibration adjustment is done without issue but the temperature still reads high on the display screen and fails for high temperature, we need to enter the in/out test to determine if the issue is the temp sensor or the Digital Predg board. 

   

  Testing PT100/Display screen accuracy after calibration

• Power the unit off and connect the PT100 simulator box (if it is disconnected) to the back of the ajunc3 board as if you were performing a calibration. (img.56 and img.57)

  

  img.56- pt test.1

  

  img.57- pt test.2

• Prior to powering the unit on press and hold the up arrow on the keypad. Continue holding up as you power the unit on. Once the screen comes on release the up button, the unit will now be in the in/out test. Press and release the up button to advance to the next step in the in/out test, stop pressing up once the screen displays PT100. If you accidentally advance past the PT100 option, power the unit off and repeat these steps. 

• In/Out Test menu order

  

  img.26- in/out test

• Check the temperature reading the display screen shows against each temperature setting of the PT100 simulator. 
• If the reading is matches or is within 1-3°F replace the temperature sensor. 
• If there is a large difference between the PT100 simulator setting and the display screen value replace the Digital Predg board

If Pressure Reading is 36P even with the door open

If the pressure transducer is disconnected from the ajunc3 board the display would always read 36P and when starting a cycle, the unit will not heat at all and would display low heat. Check the connection from the pressure sensor to the ajunc3 board to ensure it is connected, if it is already connected try to disconnect and reconnect the Molex connector. If it still reads 36P with the pressure transducer connected replace the pressure transducer. 

SOLUTION:

• Load chamber properly
• Perform air jet maintenance
• Correct line voltage
• Correct wiring issue
• Replace faulty air outlet valve
• Repalace faulty heating elements
• Replace faulty solid state relay (SSR) for heating elements
• Calibrate the unit
• Replace faulty pressure transducer
• Replace faulty temperature sensor
• Replace faulty ajunc3 board
• Replace faulty Digital Predg Board