A: Yes, one of the handiest tools for diagnosing vacuum motors and other vaccum-related components, is the handheld vacuum pump. Vacuum motors may contain one or two diaphragms to push or pull and are used in heating and air-conditioning system ducts, heater control valves and more. Checking a vacuum motor is easy. Connect the pump to the fitting on the motor and apply at least 10 in. Hg. of vacuum. The motor’s actuator should move. Once the actuator stops moving, watch the gauge on the pump to check for diaphragm leaks. If the diaphragm is OK, the vacuum should hold for one minute. Replace the motor if the actuator fails to move or the diaphragm leaks.