Middleby Marshall CTX Oven Troubleshooting From pizzerias to quick-service restaurants, CTX ovens are one of the top choices in the industry. Their infrared technique allows users to cook pizzas and other dishes quickly and evenly. When rare issues or error codes pop up from time to time, don’t let it stop you. This guide has Middleby Marshall CTX oven troubleshooting tips and error codes, so you can identify the problem quickly.
Middleby Marshall CTX Oven Troubleshooting Solutions
These diagnostic tips and codes apply to CTX Gemini Series models (DZ33, DZ55, DZ33II, DZ55II).
Product Won’t Cook
If the food product isn’t cooking completely or at all, check for the following:
- Improper cook time and temperature settings – When the conveyor runs too fast or temperature setting is incorrect, the product won’t cook properly. Adjust the cook time and temp to their correct settings.
- Display showing temperature low or zones failed – Turn the ON/OFF switch to off. Then, flip the main circuit breakers both off and on about two or three times to reset.
- Impeded air flow – To ensure proper air flow, redirect the unit to improve air flow.
Conveyor Belt Stops (Completely or Periodically)
Don’t worry if the belt stops when the time is set for 15 minutes or longer. This is known as “belt indexing” and is common. However, when the belt completely or periodically stops if the belt time is under 15 minutes, check for the following:
- Objects are jammed in the conveyor – Remove the obstructions from the conveyor.
- Breaker tripped – Turn the oven off and reset the breaker. Then turn the oven on. If the unit’s motor still won’t run, call an authorized service technician.
Display Shows Unreadable or Irregular Characters
This usually occurs when voltage spikes cause interruption to programming or the display is overheating. As a remedy, please do the following:
- Step 1. Turn the keypad to off and then back on. Then, turn the main circuit breakers on the electrical panel to off and then back on. This should restart the unit’s program.
- Step 2. If the display remains unreadable, see if the filter is clean and the cooling fan is running. If the fan isn’t running, call an authorized service technician.
Display Won’t Show READY after Oven is on for 20 Minutes
If the oven isn’t reaching set temperature, it’s likely caused by a contact not closing or a failed temperature probe or element. As a remedy, please do the following:
- Step 1. Check the set and actual temperatures for all zones.
- Step 2. If the actual temperatures aren’t within +/- 6 degrees Fahrenheit (-14 degrees Celsius) of the set temperature within 30 minutes, call an authorized service technician.
CTX Oven Error Codes
Below are potential error codes that might appear on the CTX oven display:
OVER TEMP SHUTDN ZONE
- Error – Over temperature error
- Cause – This occurs if at least one zone’s actual temperature exceeds the maximum allowed temperature of 980 degrees Fahrenheit (526 degrees Celsius).
- Remedy – This will need to be remedied by an authorized technician.
EXT. AMB SHUTDN
- Error – External ambient error
- Cause – This happens if external ambient temperature exceeds 150 degrees Fahrenheit (65 degrees Celsius).
- Remedy – Check the axial cooling fan at the lower front of the oven. See if it’s working properly and clean. Also, make sure the temperature in the area around the oven is reduced. If the fan isn’t running, please call an authorized technician for assistance.
INT. AMB SHUTDN
- Error – Internal ambient temperature error
- Cause – This occurs if the internal ambient temperature exceeds 150 degrees Fahrenheit (65 degrees Celsius).
- Remedy – As you would with an external ambient temperature error, see if the axial cooling fan at the lower front of the oven. check if it’s working properly and clean. Also, make sure the temperature in the area around the oven is reduced. If the fan isn’t running, please call an authorized technician for assistance.
- Error – Jammed conveyor
- Cause – This happens if the conveyor stopped when the speed setting is between 1-60 minutes or the conveyor runs at full speed.
- Remedy – Remove the item blocking the conveyor and/or reset the circuit breaker on the front of the control panel. If the conveyor isn’t moving, have it repaired by an authorized service technician.
- Error – Conveyor runaway
- Cause – This happens when the conveyor runs at full speed.
- Remedy – See if there is a proper speed setting. If the speed setting is correct, but the conveyor is still running too fast, contact an authorized service technician to repair.
Need more assistance with CTX oven troubleshooting? Check out our collection of CTX manuals for help.