My pool heat pump is occasionally making a loud noise from the black cylinder inside. It goes away if I turn the unit off/on. Sometimes it's good for days. Same normal noise just 100x louder. Ideas?

Dave Harris

• 117 Answers
• Posted on Sep 24, 2007

SOURCE: Makes a loud humming noise while operating

Almost certainly, the component called the "magnetron" has died. This is the valve (tube in the US) which actually generates the microwaves. The loud humming is the transformer that supplies the magnetron being overloaded and/or the magnetron itself. If the rest of the appliance is OK and not too old, the magnetron can be replaced. If you aren't familiar with these appliances, you *must* get this done by someone who understands the dangers of messing with them - if you get it wrong, they can bite! In some countries, only qualified engineers can buy the spare parts. In the UK, the part costs around £40 - £80, depending on the model. If the appliance is more than around three years old, it may be a false economy to repair it as other parts may fail soon after the repair.

SOURCE: pump motor makes loud noise when pump comes on

If this is a high pitched sound, then this sounds like you have bearings that are starting to go out.  There is not much that you can do to prevent eventual failure.
The only other option that I see is that there is something causing friction inside the pump between the impeller and diffuser.  

Mike Butler

• 6674 Answers
• Posted on Jan 22, 2009

SOURCE: Car makes funny noise upon starting on very cold days

Have your power steering belt checked and adjusted, or replaced if worn.

Perry Putnam

• 144 Answers
• Posted on Jan 22, 2009

SOURCE: Heat pump is humming loud>

When the heat is not on. Go to the T-stat and turn the fan to the on position. With the blower now running is it making the noise? If so you probably either have something in there such as the filter that was mentioned, a piece of paper etc. or one or more of the blades on the blower wheel is vibrating. Don't let the condition persist w/o having it checked out or you may turn a simple fix into a costly one.

SOURCE: fujitsu heat pump noise

i would check the blades on the condenser fan motor and make sure they are not hitting anything if they are not, spin the fan see if the fan spin freely, it should, if it doesn't it could be the bearing in the motor are dry and going bad