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below freezing. This feature will prevent freezing air from being brought into the system 1. Ensure the temperature is being displayed on the Carel controller. If it shows “#####” or “*****” then there is an issue with the temperature sensor, or the wiring between the sensor and the Carel controller. 2. Ensure the system is set to “Winter” mode if the outdoor air is expected to be below freezing. i9. “Discharge Temp Sensor” Shown on the Carel Display The Carel controller did not detect a signal from the discharge temperature sensor. 1. Inspect the discharge temperature sensor 2. Inspect the wiring between the temperature sensor and the Carel controller. i10. “Booth Doors Pop Open When The Fans Turn On” The acceleration time on the exhaust VFD needs to be adjusted so that the exhaust fan will ramp up more quickly which will maintain a negative/neutral pressure in the booth. 1. Adjust exhaust VFD parameter P7 to 30 (seconds). The lower the value, the faster the exhaust fan will ramp up to speed. Do not set below 20 unless instructed to do so by the factory. i11. “Booth Doors Pop Open When The Fans Turn Off” The deceleration time on the exhaust VFD needs to be adjusted so that the exhaust fan will ramp down more slowly which will maintain a negative/neutral pressure in the booth. 1. Adjust exhaust VFD parameter P250 to 9999 (ramp to stop) 2. Adjust exhaust VFD parameter P8 to 45 (seconds) or higher. The higher the value, the longer it will take fan will ramp down to a stop. i12. “Fan begins to ramp up, but then turns off. No faults shown on the Carel controller or VFDs” Disconnect all wiring going to door limit switches and compressed air solenoid, then try to run the fans. If the fans operate normally, then there is an issue with the field wiring for the door limits, or compressed air solenoid (check for shorts to ground, mis-wired contacts, etc.) Do not install a jumper between terminals 74 & 2 – this will cause a direct short to ground when the VFDs prove the fans are running. i13. “Random blower start fault and operator does not have to reset anything, just presses start button to resume normal operation” 1. Inspect all relays in the main control panel to ensure they are securely attached to their base. 2. Inspect all wiring connections on the top and bottom of the relays (look for loose connections). 3. Gently tap on each relay while the unit is in operation. If the fault occurs, then one of the relays could be defective and should be inspected/replaced. 4. Ensure no unauthorized field wiring modifications have occurred. Adding unauthorized components (larger compressed air solenoid, alarm buzzers, stack lights, etc.) to the system can increase the amperage draw on the control transformer which will create voltage drops that will cause unexpected behavior in the system.
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