Change Continuity

Tip: Test Switches and Contactors for Continuity

By Gary McCreadie

A number of years in the past I had a re-occurring subject with a sure rooftop unit, every time I might cycle the ability from the native disconnect, two of the three fuses would blow.  Not one of the masses throughout the unit had been chargeable for this subject so I turned my focus to the disconnect change itself.  With the ability off on the foremost and locked out, I closed the native disconnect and checked the continuity by means of every of the three legs.  I don’t recall the precise readings, however they weren’t constant.  The disconnect was changed and the issue disappeared like an previous good friend that owes you cash, you understand the one.  

It’s good apply to verify change, contactor and relay continuity on a preventative  upkeep and repair calls.  For instance, you could have a compressor blowing fuses intermittently.  Shut off energy to the unit, verify to make sure that energy just isn’t current throughout the electrical cupboard and push within the contactor serving the compressor as if it had been in operation.  Set your meter to ohms and verify continuity throughout every leg of the contactor.  The ohm readings needs to be very low and constant on all legs.  

Try this video of a stay service name the place a faulty change was the basis explanation for the problem 

It was additionally discovered that the motor had failed because of the faulty change.  The motor and change had been changed and the issue was rectified.  Previous to the analysis, the motor starter was reset a number of instances over a couple of months.  

Glad HVACing

Gary McCreadie