Compressor Will Not Start
       When It Is Cold

So, your air compressor will not start when it is cold. Or, it starts sluggishly.

This is often the case when the compressor is a oil-lubricated model, and it is stored in an uninsulated garage or other outbuilding when the outside temperature drops into the low 30's (F), or even colder.

Marginal Motors

Many DIY type oil-lubricated air compressors have marginal power plants. By that I mean that the motors are often as big as they can be to even run on a 120 VAC circuit, and without the added juice from a start capacitor to overcome the amperage draw on inrush startup of the motor, the circuit breaker would pop all the time when the compressor motor tried to start.

That is when the temperature is nominal, mid-fifties or so (F) or higher. The capacitor and power supply, working together, can get the compressor motor running every time, unless there is a mechanical or electrical issue.

Chill The Compressor

Now, let's take that same compressor and put it in the unheated garage. And, it is mid-January in North Dakota, for example. Think it is going to be cold in that garage?

What is an oil-lubricated compressor lubricated with?

Oil, you answer. And, you already know what happens to oil when it gets cold, don't you? The colder it gets, the more that oil thickens. If it is cold enough, that oil will freeze almost solid.

Now, you have the internal workings of your air compressor essentially stuck in a cold, thick oil mass, and you throw the switch to start it up.

What Happens?

Either nothing at all happens, or, depending on the fuse delay, your breaker or fuse will likely pop.

Your air compressor is trying to start. It just cannot get enough amperage out of the supply circuit, even with the capacitor kicking in its charge, to start the motor turning against the added load of the frozen or thickened oil. The motor continues pulling more amps in trying to go until the circuit breaker or fuse lets go.

You know how difficult it is to start your car on sub-zero days. Your oil-lubed, and even some non-oil-lubricated models will respond to the cold the same way.

If you are having a problem getting your air compressor to start when it is really cold, warm it up! Bring it into a heated area for an hour or so before you need to use it.

Both your compressor start circuit and the mechanical parts of the air compressor will thank you for it.