My home's a/c compressor comes on but not the fan on top of it.....new capacitor??

[redgtxdi]

So wife said she turned in a/c today and sounded horrible. (I love coming home to problems after a day of a bazillion work problems). Anyway, I check and realize that the compressor goes on but not the fan on the top of it that blows all that hot air in your face looking on top of it.

I pulled the panel and it has a dual run capacitor. I find it funny that the 5amp portion would go before the 50amp portion but whatever. I'm assuming that's the culprit. Looks like this......

http://www.grainger.com/Grainger/DAYTON-Dual-Motor-Run-Capacitor-4UGZ9?Pid=search

Assuming that's the case, anybody know if it matters which particular prong the wires go on so long as I match up "herm", "common", "fan" posts/wires from the old cap? (Solved, looks like prongs share each individual post so no matter)

EDIT: Where to buy that I can pick up so I don't have to wait?

 

[Mixolydian]

Yes this will likely fix the problem. Had the same thing happen to mine last year and a $5 capacitor was all it took to get it working again.

 

[Jumpem]

I needed a new fan motor ($372).

 

[redgtxdi]

I needed a new fan motor ($372).

Bummer!

The top of mine is bloated and is above the rim of the top at one point. (Though its hanging upside down so I'm a contortionist to look at it). I'm hoping that's a sign its just the cap. I don't think it was bloated last time I looked at it a couple years ago during a Home Depot courtesy inspection.

I also think I answered my question on the prongs as looking more closely, the prongs are part of the same post for each....errrr.....post.

 

[Mixolydian]

Bummer!

The top of mine is bloated and is above the rim of the top at one point. (Though its hanging upside down so I'm a contortionist to look at it). I'm hoping that's a sign its just the cap. I don't think it was bloated last time I looked at it a couple years ago during a Home Depot courtesy inspection.

I also think I answered my question on the prongs as looking more closely, the prongs are part of the same post for each....errrr.....post.

bulging cap = needs replaced.

 

[Red Squirrel]

Could be the cap (for the fan motor) or the fan motor itself. Try the cap first given it's the cheapest part.

Or you can go redneck style and just strap a couple box fans on it.

 

[Engineer]

Probably motor. Since the capacitor is a starting capacitor, turn the unit on and give the motor a big spin with a stick/screwdriver/whatever. If it runs, it will be the capacitor. If it doesn't, it could be either capacitor or motor.

I personally think motor but that's just me.

 

[weadjust]

So wife said she turned in a/c today and sounded horrible.

Capacitors don't sound horrible when they fail. Bearings in the fan motor do. Take the fan shroud off and spin the fan to see if the fan spins easily. I'm guessing no.

 

[redgtxdi]

Capacitors don't sound horrible when they fail. Bearings in the fan motor do. Take the fan shroud off and spin the fan to see if the fan spins easily. I'm guessing no.

Yes, fan does spin easily.

I couldn't get wife to reproduce sound so who knows and it didn't do it while I was trying but then again it wasn't spinning at all either.

 

[Newbian]

Check for mice in it.

 

[CPA]

Like Mixo said, if the cap is bloated then it needs to be replaced. Plain and simple.

 

[natto fire]

Yes, fan does spin easily.

I couldn't get wife to reproduce sound so who knows and it didn't do it while I was trying but then again it wasn't spinning at all either.

There is a good chance that it is just the start capacitor, which usually creates an open circuit. If it seems like it is drawing lots of current (buzzing, high voltage drop) then a locked rotor condition might have damaged the cap. It is possible to get locked rotor even when rotor spins freely. Bad brushes or commutator can cause that, which usually gives a mechanical clue when turning the motor, but still spins. Granted, you will probably not be able to hear buzzing on the condensor fan due to the compressor being on.

It might be easier to just pull the cap and replace instead of further diagnosis, but it is possible to narrow it down more. Could even be something as simple as a contactor going bad that switches power to the motor.

 

[Mixolydian]

New. Cap.

Do you have a Grainger location near you? If so you can order the part online and pick it up at will-call. That's what I did.

 

[redgtxdi]

Yep, $40 later it's good to go. Thank God!!! I did not want it to be something expensive.

I wish I could have heard whatever the wife heard but A/C is currently running smooth and quiet with nice cold air blowing out.

Aaahhhhhhhhhhhhhhhhhhhhh!

Thanks for all the quick feedback, gang!

 

[redgtxdi]

One more thing I've noticed and I'm pretty sure it is the case....... The compressor seems to be quieter than before.

I thought a cap just assisted in the initial "kick" but I even asked the wife and she agreed. We even went and stood outside by it and it's definitely quieter than it used to be.

Any particular reason a new cap would cause for that to be so?

Thx

 

[Engineer]

yep, $40 later it's good to go.!

ack!!! D: D: D:

 

[Mixolydian]

ack!!! D: D: D:

Yeah, mine only cost about $5!

 

[Wyndru]

I have an off-topic question about these compressors, do they have to be close to the AC, or is it possible to move them about 30-40 ft. from it's original location if you run the pipe and electrical?

Ours is in a horrible location, I was thinking about moving it to the other side of the house so I could build a deck, I wasn't sure if there is any concerns I need to be with the length.

 

[Mixolydian]

is it possible to move them about 30-40 ft. from it's original location if you run the pipe and electrical?

Yes.

 

[redgtxdi]

It was a 5/50 370 dual run (compressor and fan).

I don't think I'd want a $5 cap doing that job.

Any idea on the noise volume?

 

[TXHokie]

Yep, $40 later it's good to go. Thank God!!! I did not want it to be something expensive.

I wish I could have heard whatever the wife heard but A/C is currently running smooth and quiet with nice cold air blowing out.

Aaahhhhhhhhhhhhhhhhhhhhh!

Thanks for all the quick feedback, gang!

ATOT saved my butt one summer too when our AC capacitor blew. It was on a hot Friday afternoon and AC company wanted $250 to come out Saturday. Grainger was closed for the weekend but I found the caps a a local electric motor repair shop that was open on early Sat morning- exact replacement for $10 so I bought a spare too. Just to be safe I took the fan off too and had them tested it. I got to be the hero that weekend when the temp hit 100 and we were chilling.

 

[stormkroe]

I have an off-topic question about these compressors, do they have to be close to the AC, or is it possible to move them about 30-40 ft. from it's original location if you run the pipe and electrical?

Ours is in a horrible location, I was thinking about moving it to the other side of the house so I could build a deck, I wasn't sure if there is any concerns I need to be with the length.

Absolutely. On the AC unit it will probably tell you how many lbs(or ozs) of freon you need per foot of copper line. Sadly, you'll lose most of the freon when the fridgy couples it. Good one's can capture and re-use.

As far as power goes, just be sure you keep the disconnect within sight of the unit and no more than 3 meters away (CEC code 28-604 (sub 5). NEC is probably the same.

 

[stormkroe]

It was a 5/50 370 dual run (compressor and fan).

I don't think I'd want a $5 cap doing that job.

Any idea on the noise volume?

If there's a real noise difference it probably got louder gradually as the capacitor began to fail and you didn't notice it. Depending on how the cap failed it could have made a bad noise. There's a separate coil in the hermetically sealed motor that relies on one of the line inputs to be out of phase (amount determined by the farad rating of the cap) with the pure L1 and L2. Think of this as a sort of bastardized 3 phase motor. Since this 'helper' coil is made to operate in a phase somewhere between L1 and L2, a shorted cap would make it in phase with which ever line the cap was paralleled from. You'd get both coils energizing at the same time, and it would probably sound terrible. It would also eventually destroy your motor. This would be much easier to explain if we were in the same room and I had a pencil and paper to draw pictures with

 

[redgtxdi]

Ha ha.....I do get the gist, so thanks for that!

I'm just glad it's working!

:thumbsup:

 

[bryanl]

Fans seize, but change the capacitors anyway. Make the wiring connections for the fan waterproof, vibration resistant and sunproof. Any plastic wire ties must be sunproof, not just black.