Question: What could be the reasons for a vacuum pump having no vacuum? 

Answer:

1、 Incorrect motor rotation direction:

Solution - Replace the motor and adjust the two wires to the correct optional direction.

2、 No working fluid entering the vacuum pump:

Solution - Check if the working fluid valve is unblocked and if any liquid enters the vacuum pump.

3、 Severe air leakage in the system:

Solution - Check if there are any bypasses open in the vacuum pump suction pipe.