Over time the filtering media inside the intake filter on an air compressor can become plugged with dust and dirt.
![older sears 240 air compressor 3.5 hp 240 volt older sears 240 air compressor 3.5 hp 240 volt](https://i.ebayimg.com/thumbs/images/g/5acAAOSwSspgiQgs/s-l225.jpg)
If the compressor starts now, an insufficient current could have been the problem. Try to eliminate any other electrical draws on the same circuit when you are attempting to start the compressor. Plug the air compressor directly into a socket, preferably one with a 20 amp circuit breaker rather than a 15 amp circuit breaker. Plug the compressor cord directly into a wall socket that has few (or preferably no) other electrical devices that could pull power from that same circuit when your air compressor is starting or running. If you are using an extension cord or a power bar, don’t. The power supply to the air compressor must be clean and through the shortest line possible.
#Older sears 240 air compressor 3.5 hp 240 volt how to
How to fix when air compressor just hums Power Supply It is necessary to address the “why” as quickly as possible when your air compressor just hums. You do not want to let your air compressor motor sit there humming as it will quickly overheat and cause damage to the motor. Some electric motors, particularly those that run on 120 AC current, run very close to the edge in terms of power available from the 120 AC supply versus the minimums needed to keep the motor running, let alone, get it going.Įven with the boost from the start capacitor, if there is additional load on the motor at compressor start up, it cannot get going, and it sits their humming, as it is getting power, just not enough. Once going, the motor uses less current to stay running. The electric motor uses the current available from its start capacitor to add the additional start up current that is necessary to kick the motor into action. When it sends power into the circuit, it does it all at once and very quickly. Think of the start capacitor as a quick-discharge battery. To help provide the added current on startup, electric motors above a certain size normally have a start capacitor.
![older sears 240 air compressor 3.5 hp 240 volt older sears 240 air compressor 3.5 hp 240 volt](https://storage.bhs.cloud.ovh.net/v1/AUTH_e7d15450bedd40b9b599e075527df3cb/duluth/_Craftsman_5HP__240V_Air_Compressor__320_5f34f9df3d379.jpg)
To understand why an air compressor just hums, and to try and fix yours if that is what is happening, it is helpful (I hope) to understand a bit about the air compressor motor.Īir compressor motors needs to have more current available to them when they start than is necessary when they are running.
![older sears 240 air compressor 3.5 hp 240 volt older sears 240 air compressor 3.5 hp 240 volt](https://m.media-amazon.com/images/S/aplus-media/vc/f8a0ec93-bc0f-4b64-97c2-938936732dfd.__CR0,0,960,960_PT0_SX300_V1___.jpeg)
What we are talking about is the scenario that you have just switched your air compressor on, or the air compressor tank pressure has dropped to the normal cut in pressure setting, and your air compressor just hums! Doesn’t start, just sits there humming.Īnd it’s not even a nice melody, at that! We are not talking about the noises the air compressor is making when it is running, gosh knows air compressors are loud for sure. Why is it that an air compressor just hums?