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Old 07-23-2010, 04:02 PM   #1
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Need help finding specific capacitor!


Moved into a new (older) house about a month ago. When we moved in, right after settlement we noticed the central was not working. Called a local HVAC guy (my wife found him on the internet and he was the only one who would come out on a Saturday morning). The guy showed up, popped the cover off of the outside compressor/fan unit and we both immediately noticed the problem: the start/run capacitor had literally exploded. It had (has, I still have it) two big blobs of metal sticking out of the sides of it from the explosion.

The tech said he didn't have that type capacitor, so he went to the HVAC supply house about 5 minutes away to get one. He came back and said he had to put it on order, but in the meantime he had a universal capacitor he would throw in there so he could get our AC running (I'm in the Northeast and it's been constant heat-wave this summer!). He put in the universal cap (electrocuted himself in the process - no kidding), then tried to start it up. He then had to install a 'hard start' kit. Once he got that in it started up and has been running fine for a month straight - works beautifully. One problem though - it's running in reverse. The fan is sucking in air, while the heat is being dispelled from the coils. He said "that's wierd" and seemed to be at a loss as to what could cause it. He said that, in a few days, when the replacement capacitor comes in, he'll stop by and replace it and maybe the fan will work normally again. A week later I hadn't heard from him so I called him up. He said the part still hasn't arrived. Another week...no part. That was a month ago so I've given up on him. He didn't seem like he was the sharpest bulb anyway.

I'm a former electronics tech and generally fairly handy. Watching him replace that capacitor I have no doubt I can do it as well (actually better, since I'm bright enough not to shock the heck out of myself while doing it). Problem is, I can't get anyone to sell me the proper replacement capacitor. The cap in question is:

Aerovox
Aero-Met II
Part #M26P3750W05
50+5uF 370V Plastic/Polypropylene, round

I called Aerovox and they said it was discontinued a couple of years ago, but they still have plenty in stock. Problem is, they won't sell to me direct cus I only need one or two. They only sell in bulk. The lady told me to call any of the distributors on their website and they'll be able to sell me one. Well, I contacted every single one of the distributors that serves the United States and NONE have it or will order it for me.

How can I get one of these capacitors? Or can I just get any equivalent 50+5uf 370V capacitor? Any recommendations?

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Old 07-23-2010, 04:18 PM   #2
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Quote:
electrocute [ɪˈlɛktrəˌkjuːt]
vb (tr)
1. to kill as a result of an electric shock
2. (Law) US to execute in the electric chair
[from electro- + (exe)cute]
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(electrocuted himself in the process - no kidding),
sure hope you were.

Quote:
Or can I just get any equivalent 50+5uf 370V capacitor?
bingo. equivalent also means same type of cap construction as well as the same capacity, tolerance, and voltage rating.

You can use a higher voltage rating though, just not lower.

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Old 07-23-2010, 05:17 PM   #3
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Try Grainger.

PS: The fan is running backwards either because he has it wired wrong. or, the start windings are bad, and that is what took out the cap in the first place.
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Old 07-23-2010, 07:21 PM   #4
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Thanks guys.

I actually wasn't kidding in regards to the guy electrocuting himself. I just used the wrong word - he 'shocked' himself. He is still alive. But as I'm standing there, sensing he was making a mistake in not cutting power before trying to attach the new cap (a universal one at that, so it had lots of terminals, all close together), before I could say anything all of a sudden I see an arc and his arm gets snapped back, right into a big pile of bricks. Fortunately he was fine after a few seconds of bugged out eyes : ) He made sure to cut power after that!

So I found this one on Grainger:


All the ones on Grainger (and everywhere else that I looked) seem to be different in two ways:

1. They are metal, instead of plastic/polypropylene like the original from Aerovox was. I'm guessing this shouldn't matter?

2. The ones I'm seeing online have two terminals, whereas the original has 3 terminals, with each terminal marked one of:

FAN
HERM
and
COM

I'll pull out the schematic tomorrow, as I'm guessing that one of the terminals was unused?
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Old 07-23-2010, 07:37 PM   #5
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Canister doesn't matter.
But. You need a dual capacitor. That would be one with 3 terminals.



Or, you need to get 2 separate ones. A 50x370, and a 5x370. And then you would have some rewiring to do.
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Old 07-23-2010, 07:39 PM   #6
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A 50+5 will have all three terminals.Probably going to be smaller in diameter then your original so mounting will change, not a big deal.
Check that he has the fan going to a 5 spot and not the center common terminal. That would make the fan run backwards.
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Old 07-23-2010, 10:23 PM   #7
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Originally Posted by mark2741 View Post
Moved into a new (older) house about a month ago. When we moved in, right after settlement we noticed the central was not working. Called a local HVAC guy (my wife found him on the internet and he was the only one who would come out on a Saturday morning). The guy showed up, popped the cover off of the outside compressor/fan unit and we both immediately noticed the problem: the start/run capacitor had literally exploded. It had (has, I still have it) two big blobs of metal sticking out of the sides of it from the explosion.

The tech said he didn't have that type capacitor, so he went to the HVAC supply house about 5 minutes away to get one. He came back and said he had to put it on order, but in the meantime he had a universal capacitor he would throw in there so he could get our AC running (I'm in the Northeast and it's been constant heat-wave this summer!). He put in the universal cap (electrocuted himself in the process - no kidding), then tried to start it up. He then had to install a 'hard start' kit. Once he got that in it started up and has been running fine for a month straight - works beautifully. One problem though - it's running in reverse. The fan is sucking in air, while the heat is being dispelled from the coils. He said "that's wierd" and seemed to be at a loss as to what could cause it. He said that, in a few days, when the replacement capacitor comes in, he'll stop by and replace it and maybe the fan will work normally again. A week later I hadn't heard from him so I called him up. He said the part still hasn't arrived. Another week...no part. That was a month ago so I've given up on him. He didn't seem like he was the sharpest bulb anyway.

I'm a former electronics tech and generally fairly handy. Watching him replace that capacitor I have no doubt I can do it as well (actually better, since I'm bright enough not to shock the heck out of myself while doing it). Problem is, I can't get anyone to sell me the proper replacement capacitor. The cap in question is:

Aerovox
Aero-Met II
Part #M26P3750W05
50+5uF 370V Plastic/Polypropylene, round

I called Aerovox and they said it was discontinued a couple of years ago, but they still have plenty in stock. Problem is, they won't sell to me direct cus I only need one or two. They only sell in bulk. The lady told me to call any of the distributors on their website and they'll be able to sell me one. Well, I contacted every single one of the distributors that serves the United States and NONE have it or will order it for me.

How can I get one of these capacitors? Or can I just get any equivalent 50+5uf 370V capacitor? Any recommendations?
Aerovox!!!!

These plastic caps are pure junk!!

Get an Amrad made in the USA Turbo cap and simply jumper it to the configuration you need. Try and avoid Mexican and Chinese capacitors.

Last edited by hennyh; 07-23-2010 at 10:27 PM.
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Old 07-24-2010, 10:05 AM   #8
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Thanks again guys for the assistance/advice.

I had the opportunity to do more research on this. This morning I opened up the cover on the outside fan/compressor unit and snapped some pics of the wiring/universal cap that the tech installed. As I said before - the tech said he would be back in a few days (that was a month ago) to replace it with a non-universal cap that was on order, but he hasn't come back and won't return my calls so I gave up on him.

He used a motor-mate universal cap, along with a hard-start kit (the hard-start kit was tucked away so I couldn't get a good pic). He first installed the universal cap but it wouldn't start, so he installed the hard-start kit and it's been running ever since, but in reverse. Based on the instructions for the motor-mate that I found here:


It appears to be wired correctly:


I can scan the wiring diagram from the unit if that will help, but basically:
Red wire goes from 50uF on cap (Common) to Contactor
Blue wire goes from 50uF on cap (Herm) to Compressor
Brown wire goes from 5uF on cap, to Fan motor

So I looked through this pic and compared it against the wiring diagram that was on the outside unit and it looks like he wired it correctly. Problem is, the unit is running in reverse still. It's been running fine that way for almost a month now (nice and cool in the house - no problems - particularly impressive in this East Coast heatwave), but it bothers me that it's running in reverse (i.e., the heat is being expelled from the sides/coils, and the fan is sucking in air rather than expelling it), and may be running either inefficiently or there may be long-term damage by running it in reverse. I hate to call out another tech but I may have to.

The hard-start kit wiring appears to be correct too.

Now, it is VERY possible that the unit has always run this way. I've only owned the house for a month and as I originally said, the unit was not working at all when I moved in due to the blown run cap. The HVAC tech said that some systems were designed that way (something about 'so they don't suck in grass clippings'). But he wasn't sure why it was running in reverse. He's missing in action now so I guess he gave up.

The unit is an ArcoAire, if that helps. There's no other information as there used to be a sticker on the outside but it fell off before I took ownership of the house - I can still see the writing from the 'glue' that held the sticker, but it is unreadable. I'm gonna take another look today but not hopeful.

What could cause this thing to run in reverse? Should I be concerned or just quit worrying? It's an old unit - about 21 years old, so eventually it's gonna go...
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Old 07-24-2010, 10:42 AM   #9
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Does the fan motor look like it may have been replaced sometime before you bought the house.

Look at your wiring diagram for the unit.

Where does it show the fan wires going to.

Looks like your missing a fan wire on the cap.
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Old 07-24-2010, 10:47 AM   #10
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if he bumped in the compressor contactor at any time during his cap arama call the pressures weren't equalized and th compressor just sits has to equalize...putting a hard start on it is pushing the windings to over come the PSI difference..and leads to compressor burn out..the caps should be seperate and dedicated for each load....does your stat have a compressor anti-recycle off time setting might want to put in a adj TD on the 24V into the cond and dump that HS kit
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Old 07-24-2010, 11:09 AM   #11
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Originally Posted by beenthere View Post
Does the fan motor look like it may have been replaced sometime before you bought the house.

Look at your wiring diagram for the unit.

Where does it show the fan wires going to.

Looks like your missing a fan wire on the cap.
There is only one wire for the fan motor - the brown one. It is connected to the 5uF (yellow terminal on the univ cap). That jives with the schematic diagram - the fan motor only has one brown wire, connected to the cap. Then there is a black wire coming out of the fan motor and going to the contactor, and another black going to ground. I can't see those wires as they're inside the unit, but what I can see (and is shown in the pic) is correct per the diagram.
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Old 07-24-2010, 11:28 AM   #12
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if he bumped in the compressor contactor at any time during his cap arama call the pressures weren't equalized and th compressor just sits has to equalize...putting a hard start on it is pushing the windings to over come the PSI difference..and leads to compressor burn out..the caps should be seperate and dedicated for each load....does your stat have a compressor anti-recycle off time setting might want to put in a adj TD on the 24V into the cond and dump that HS kit
He shocked himself by touching one of the contactors on the universal cap while hooking up the wires to it.

What do you think of this plan:
1. Cut power to the outside unit (I'm not a *complete* idiot : ) )
2. Pull the two wires coming from the universal cap and going to the hard-start kit, basically removing the hard-start kit from the circuit.
3. Restoring power and seeing if the fan runs and, if so, in proper fashion (i.e., not reverse).

The original capacitor is a dual one - so both the 50 and 5uF terminals are on the same capacitor. I found what appears to be a suitable replacement capacitor here (that replaces the original cap that blown, and is now discontinued and apparently unattainable when not purchased in bulk):
http://www.newark.com/genteq/97f9970...70v/dp/81C9407

When you say this:
Quote:
does your stat have a compressor anti-recycle off time setting might want to put in a adj TD on the 24V into the cond and dump that HS kit
I don't understand. What is "adj TD".

The original capacitor that blew was really straight-forward in terms of wiring:
Blue wire to the COM
Brown wire to the FAN
Red wire to the HERM

The universal cap and hard-start kit certainly make things more confusing. I can't see, logically (keeping in mind I'm not HVAC knowledgeable at all), why the hard-start kit would cause the fan to run in reverse. But removing it makes sense to me so I'll try it and see if that works. And the universal cap seems to be wired appropriately.

I guess I'll try removing the hard-start kit and, if the unit runs, then my next step will be to order a replacement cap and when it arrives replace the universal cap with it. I want a spare anyway.

Does that sound sensible?

The compressor itself is a Copeland Scroll (can't make out the details on the sticker without taking the top of the unit off).
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Old 07-24-2010, 12:25 PM   #13
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A new capacitor isn't going to do anything that that one can't so don't waste your time ordering one. The capacitor is wired correctly so that's not the issue of the backwards fan. Double check that wire going to ground that you think comes from the fan. Never saw any color but green used for ground so it's miswired or has a splice with a color change.
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Old 07-24-2010, 01:20 PM   #14
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Try this.
http://cgi.ebay.com/Compressor-Fan-D...item19bd290d08

Or this:
http://www.routeac.com/dual-run-capa...t-uf-50-5.html
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Old 07-24-2010, 04:27 PM   #15
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There is no wire from the fan that goes to ground.

Or there shouldn't be.

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