Just a hunch, but it sounds like you'll be replacing a motor soon.

 

Sometimes a capacitor appears functional when tested with a capacitor checker and fails when placed under full load. It is possible to have an intermittent short in a wire, a faulty capacitor is more likely.

 

I've had this problem before as well. In my case, the capacitor terminals were corroded enough to prevent proper contact to the connectors. Cap tested good but fan wouldn't work. After some filing and brushing, I reconnected and it worked fine. Were the terminals on your old cap corroded?

 

Is it possible the capacitor has high ESR? I've seen this a LOT with electronics, not so much testing done with motor caps. High ESR caps will check good with many cap checkers but have a high impedance when an AC load is applied.

 

had a condenser fan that would start if you helped it seemed like something wrong with start windings, replaced motor all good. Poss. motor starting to fail.

 

When I got home I switched my meter to read ohms and it still seems to give out readings as if its working properly.

What readings from the "ohm" setting tells you it's working properly ???

What does ohming the cap tell you??

Curious.

 

Ohmmeter readings



If the needle of the meter shows a deflection (analog) to the right end of the scale and back to infinity, the capacitor is probably good. If the needle comes to rest on 0 ohms, the capacitor has a short. If the needle doesn't move, it's open. This is pretty much right out of the book...

 

In my opinion, the new cap being final resolution or conclusion on replacing a motor soon is the flip of a coin.

I advise my techs to test a cap in this procedure.

Amp draw first, prior to even wiggling a wire off the cap, if no amps, most likely open cap, verify next with cap tester. If open, def replace, if upon removing wires, they are rusty, our techs can clean terminals with small file and test again. Even at this point, we recommend new cap and terminals for longevity as once you clean them, they will rust even quicker as now the protective coating, on the terminals, in the production of the cap is removed by cleaning.

If amp draw present, disable power, verify residual power remaining in cap is discharged, remove one (common if possible) to test with MFD tester. Removing only one terminal eliminates the possibility of damaging cap terminals by 50 percent on a cap or more on a dual cap, when removing the wires.

We prefer to use cap tester vs multimeter, for this reason only. When we remove the cap and if it is taken it to the consumer, they seem to have more trust in a device connected to the cap with MFD tester on it, such as Supco MFD tester, than they do a multimeter which looks very complicated to them. Clean and cut, if the readout they see is other than such the rating on the cap, replace. Always advise the motor may still have winding damage to be tested after a new cap is installed. Some consumers enjoy being involved in the visual verification of a bad component, and further builds trust with them.

After new cap, another amp test to verify current to winding, if current is not right, and voltage is correct, replace motor, which would have required a new cap anyway, so no real waste of time.

This method of testing, was endorsed and published in the Amana servicers handbook July of 2007 as their preferred method of verification of PSC motor/cap testing.

We all have different ways of procedure, I push our techs to be consistent as to help remove doubt in their decision after a repair.

"Procedure vs OCD"

 

After new cap, another amp test to verify current to winding, if current is not right, and voltage is correct, replace motor, which would have required a new cap anyway, so no real waste of time.

I'm assuming you are speaking of current of the start winding and voltage across the capacitor?
What should the voltage and current be? If the cap is good, aside from an improper frequency, how would one be correct and not the other?

 

When I got home I switched my meter to read ohms and it still seems to give out readings as if its working properly.

This test will not give you the current capacity vs rating of the cap, only tell you if it's cycling properly, i.e. Open, shorted, Charging. A multi-meter or MFD tester can tell you the MicroFared's currently being detected.

"Procedure vs OCD"

 

View attachment 259251

Start winding or on cond fan and indoor blowers with cap use neutral side cap line for amps X 2650 divided by active volts under load of cap. This is the real deal of is the cap shunting over to the dual side and a drop of volts is happening etc. Using this method may be inherently dangerous to measure but is spot on for "no callbacks". Motor shell temp after 10 min's run time is also a must to leave the motor and walk away!

 

Take that amp reading next time. The bearings are probably bad.

 

yes, Sorry for being unclear,, speaking of the voltage line to the motor being correct, and the load on the motor correct, then if the amps to the winding are off, there is probable internal damage to the motor. (bows)

Nice Catch,, (bows)

 

[QUOTE The difference in phase is what creates the rotating magnetic field required to run the motor.

You are correct it is only a phase shift for a capacitor, however getting a Tech to not be a deer in headlights I've used the "incredibly fast on/off switch" to at least try to "fix stupid"! One has to find methods of madness that may work to get a Tech to understand. Mention Wet Bulb, Sub Cooling, Saturation Point or anything other than "beer can cold" and your back to a deer in headlights all over again.

 

Yes, I believe it. Unfortunately this is what causes many of the installation/design mishaps that we go around fixing. Supply and return air are something EVERY tech should understand, if we get that done peoples A/C units would deliver a lot more comfort. When I see an install I can immediately tell who did the work. Sometimes it's the top techs, sometimes it's the guys just starting out. On builder installs few companies can afford to pay their top techs to do the install and still make a profit on the job. The best companies in our area don't even do new construction work because they have plenty of more profitable work.