compressor motor replacement

[Charlie's68]

I have a ir ts4n5 5hp 80 gallon compressor that i have had for 2 1/2 years. Yesterday the motor quit. It will only start when i hit the reset button, and will only run for 8 seconds, get hot and quit. It does this even when the belt isnt connected to the pump. So i guess that means a motor for me. What are some good brands? I know baldor and dayton are good, but i cant find anything from them. How about a o smith? Leeson? Has anyone else had motor failures like this?

[goodfellow]

If it's a 220 v motor, check the "run" capacitor -- it could be toast. It's rare for a good motor to short the windings in a 2 1/2 year time period.

The fact that it starts without a problem suggests that the "start" capacitor is doing its job.

[Charlie's68]

yes its 230 volt, capacitor start/capacitor run. How do i go about checking the run capacitor? It is not swelled or anything like that.

[HSS]

sounds to me like the centrifical switch is stuck closed and not letting it get out of the start winding.

[HSS]

try starting the motor and tapping the back of the motor at the same time.

[TheToolMan]

I run a electric motor repair shop so please take my advise. get a new motor. Dont get it repaired. A new motor is cheaper. By your problem description i would say the windings are shot. 99% of the time if its getting hot its the windings

[goodfellow]

Yes, it could be the switch. The switch should disengage after the motor reaches a predetermined RPM range. It's usually underneath the bell guard in the back of the motor. Although this is a common problem with cheaper Asian motors, good compressor motors should not be prone to that happening.

The contacts have a tendency to stick and pit as in old point type distributors. Hence. they can slightly "weld" themselves together and not separate. If they are stuck, you can try resurfacing them with emory cloth, or an ignition point file.

As far as the capacitor is concerned, your nose is the best first diagnostic. If you smell anything burnt, then you found the trouble. To test the capacitor further you need an Ohm meter. Unfortunately, with an Ohm meter doing an "incircuit test" is not very accurate (you'd need a capacitor tester for that). So you might have to disconnect the the capacitor from the circuit to perform a proper test.

Make sure you discharge the cap first though -- the proper way to that is to use a jumper wire with a 10K ohm resistor in the circuit. Although not recommended, some simply bridge the connections with a screw driver -- this may cause a good spark!

Once it's discharged, hook an ohm meter to both sides and watch the meter. A good capacitor will show no resistance (0 ohms) at first, and gradually build up resistance as it charges (using your meter's battery as a power source). If the meter just shows infinite resistance, or no resistance at all -- then the cap is probably bad.


EDIT: Or take Toolman's advice -- he's probably the authority on this. Experience is the key here.

[Charlie's68]

thank you for the adivce. The contacts are good. I tested the capacitors, and both started at 0, and slowly went up. i think i am going to try a a o smith motor.

[Danglerb]

This is the type of thing where you have to weigh your skill in the area, vs replacement parts, vs how soon you need it working.

I like to fiddle with electrical stuff, so I would start by replacing the capacitor with something out of my junk pile.

I get the feeling you don't like to fiddle with electrical stuff, so best might be to write down all the info on the motor plate, take a couple pictures with your cell phone of the mounting brackets etc. and go find a replacement.

[Charlie's68]

its not that i don't like to fiddle with crap, but i have no access to parts like this, so i just cant go try another capacitor.

I need the compressor soon.

[KenS]

FWIW: If the new motor does not have an internal reset button, you may want to consider adding a magnetic starter.

[Charlie's68]

what do you guys think of something like this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=350060561762

matches all of the specs, sf, amp, rpm, mount service, shaft size....etc

[nissan_crawler]

For that price, I would buy a baldor from weco-group on ebay.

[LoneGunman]

For that price, I would buy a baldor from weco-group on ebay.

Yup, cannot be happier with my weco_group 7.5 hp Baldor.