Honeywell ML7420 ML7420A6033E Non-Spring Return Electric Linear Valve Actuators

ML7420A6033E: Suitable for Honeywell HVAC valves, with a built-in positive and negative action plug, which can provide 0-10Vdc or 2-10Vdc modulation control.

Common faults and solutions for ML7420A3063 are as follows:

Actuator does not work

Power supply problem

Fault description: The actuator has no power input or the power supply voltage is abnormal.

Solution: Check whether the power supply line is connected normally, whether there is a circuit break or short circuit, and measure whether the power supply voltage is within the range of 24Vac (±15%). If the voltage is abnormal, check the power supply equipment and circuit.

Input signal problem

Fault description: No input signal or abnormal signal.

Solution: Check whether the signal line connection from the controller to the actuator is good, and use a multimeter to measure whether the input signal is 0-10Vdc or 2-10Vdc. If the signal is abnormal, check the controller output and related settings.

Motor fault

Fault description: The motor winding is short-circuited, open-circuited or the motor is burned.

Solution: Use a multimeter to check whether the motor winding resistance is normal. If there is an abnormality, replace the motor; if the motor is burned, replace it with the same model motor.

Abnormal actuator action

Unsmooth or stuck action

Fault description: The actuator is stuck or inflexible during operation.

Solution: Check whether the connection between the actuator and the valve is loose or stuck, clean the connection parts and valve screw and other parts, and apply an appropriate amount of grease; check whether the gears, bearings and other mechanical parts inside the actuator are worn or damaged. If damaged, replace them in time.

Abnormal action speed

Fault description: The actuator runs too fast or too slow.

Solution: Too fast speed may be due to abnormal power frequency. Check whether the power frequency is 50Hz/60Hz; too slow speed may be due to insufficient motor power, excessive load or aging of internal circuit components. Check whether the motor is normal, reduce the load, and replace the aging circuit components.

Feedback signal problem

No feedback signal

Fault description: The controller cannot receive the feedback signal from the actuator.

Solution: Check whether the feedback signal line connection is normal, whether there is a break or short circuit; check whether the internal feedback circuit of the actuator is faulty, such as whether the potentiometer, sensor, etc. are damaged. If damaged, replace them.

Inaccurate feedback signal

Fault description: The feedback signal does not match the actual valve opening.

Solution: Recalibrate the feedback signal of the actuator, and make the feedback signal consistent with the actual valve opening by adjusting the potentiometer inside the actuator or setting parameters; check whether the valve opening detection device is working properly. If there is any deviation, adjust or replace it.

Overheating problem

Fault description: The actuator overheats after running for a period of time.

Solution: Check whether the working environment temperature of the actuator is too high, and improve the ventilation and heat dissipation conditions; Check whether the load is too large, causing the motor to overload. If there is an overload, adjust the load or replace a higher power actuator; Check whether the motor fan is running normally. If the fan fails, replace it in time.

Noise problem

Fault description: The actuator generates abnormal noise during operation.

Solution: Check whether the mechanical parts are loose, tighten the loose screws, nuts, etc.; Check whether the gears, bearings and other parts are worn. If there is wear, replace the worn parts; Check whether there are foreign objects or impurities inside the valve, and clean the inside of the valve.