Air Compressor Problem

[Temp97]

Everything I touch this past week has gone bad!!! Now it's my air compressor. I have a Craftsman, 30 gallon 5 HP, Oil less type. Few years old and sits in my basement and only used for my finish nail gun for the most part. 2 weeks ago worked fine. Now it only runs at what seems to be 1/2 power and then trips a circuit within!!!!! I'm beginning to think that my damp basement may have done some damage to the wires or something to that effect. Anybody have any ideas?

Thanks

 

[radioman]

Have you pulled the plastic covers to visually inspect the motor windings or the casing of the motor ? if it rusty, chances are its time for a replacement. If it looks fine, try taking out of the basement and move to a known 20amp outlet and run it for awhile. sometimes the plugs that is exposed to damp areas can rust and cause power issues like you are experiencing.

 

[Bird]

Do you still have your owners manual? I used to have what may have been the same compressor. Mine never had a motor problem, but I sure got tired of rebuilding the compressor. The good part is they are very simple to work on. It sounds as if your problem may be the motor.

 

[CharlieS]

It could be either a motor or compressor problem. If the compressor is dragging that would put increased load on the motor, increasing amp draw which could of course cause a breaker trip.
A motor going bad would have the same symptoms.
I'm not familiar with this compressor, but if you can unhook the compressor either by removing the belt, if its a belt drive, or by what ever method is necessary, does the compressor turn freely? with perhaps a little resistance on the compression stroke? Does the motor turn freely when spun by hand?
with the compressor unhooked does the motor then power up freely?
The easiest way to do a preliminary test of the motor is with a clamp on amp meter, comparing actual amp draw at start up and running, with data on the motor name plate. that data should include maximum starting amps as well as load running amps.
The next step then would be to have a motor shop test the motor.

on a side note, several years ago, i had problems with a craftsman 60 gallon upright compressor (made by devilbliss) that kept blowing head gaskets on the pump itself. while under warranty sears replaced the gaskets several times and the valve plate once. The last time it happened i contacted devilbliss directly and they replaced the entire pump. That solution finally worked as to date, no more blown gaskets. To this day i'm convinced the heads on the pump were slightly warped but knowing how service on things like this go, service tech's generally think the consumer knows nothing.

 

[Bird]

It would be my guess that this compressor, as the one I had of the same size and brand (and yes, made by DeVilbiss for Sears) is a direct driive. But you can remove the cover that conceals both motor and compressor pretty easily.

 

[E/S]

Does it use a start capacitor?
That can really mess up your motor.

E/S

 

[Stonehaller]

My guess is that it has a universal type motor with brushes and the problem is a short in the rotor. It could be a bad brush and you can probably get replacement brushes from Sears. Check the brushes for damage. They should have a smooth concave surface that mates with commutator, (copper bars on the rotor that the brushes ride on). Check the commutator for scoring and burns. If it is scored up, you need to get it turned. It will be difficult to find anyone that repairs these motors anymore and you may have to buy a new one.

If the motor does not have brushes, it must have a capacitor which is probably going bad.

 

[SPYDERLK]

Have you drained the tank lately?

 

[DanD78]

Make sure both wires are hooked up in the pressure switch. My brother in law had the same problem when he hooked his up. Had a 220V motor and he only had it one leg of the 220 hooked up right. The motor did run on 110V just like yours is.

Dan

 

[k0ua]

could be the brushes, or could be the capacitor.
If it ran well last time.. and now it doesn't, I would lean more to capacitor
James K0UA

 

[RPW]

If it seems to only be running at about half speed there is a good possibility that the compressor side (piston etc) has gone bad. Mine will do that every few years. You can tell by removing the shroud and with the compressor turned off and preferably unpluged manually rotate the compressor. If it is stiff to turn during the full revolution then the piston has gone bad. Not to worry as all you need is the model number and you can get the entire parts breakdown off of the Sears website and can also order the replacement parts. They're not that expensive. And BTW mine is about 20+ years old and I still can get parts from Sears.

 

[Soundguy]

make sure it's not on an extension cord.. also try it on another recep somewhere else. I had a comp that kept tripping in my garage.. turns out the recep it was plugged into was bad / restive.

also know that they have a hard time starting due to v-drop @ load on a small extension cord.

soundguy

 

[DaveOmak]

Temp,
I believe there are two sets of contacts in the motor. One set starts the motor then a second set kicks in on centrifical force to bring the motor up to running speed.
If the second set doesn't kick in, the motor will only run on the start speed.
Check the sets of points inside the motor housing along with the centrifical switching mechanism.
Dave