Air Conditioner compressor wiring

daberno123 · Fri Mar 27, 2009 3:09 pm

If some of you remember I posted a topic about a week ago about getting air conditioning compressors off eBay for $20. Well I got mine but I have no idea how I need to wire it in order for it to be able to be plugged into a (US) wall socket. I'm a total noob at electronics so bear with me.

Here's a picture of everything I got:

The compressor is about 8" high and about 6" wides. It weighs about 13 pounds (heavy!)

It has three terminals on the top. One is labeled R(W), one S(V), and the third C(U). I have no idea what any of this stands for, but my common sense told me that C should stand for capacitor. I'm nearly certain that the tube on top is the output and the one on the side is the input, assuming my compressor is the same as the one on Youtube by Davidsfarm.

This is what the starting capacitor I got looks like. It also has three connections on it, One on the wire, one sticking out and one set into the capacitor. Again, I have no idea what any of these are for, but the one on the end of the wire fits over the ones on the compressor.

However, according to this diagram I found on google the capacitor should not be wired to the C terminal but to the S and R. Also, it doesn't specify which way the capacitor should go, so I don't know if it means the wire with the connector which came already on the capacitor goes to S and the other connection (which I would have to put on) goes to R or vice versa. I'm pretty sure only the top part of the diagram is relevant.

Another problem there is with wiring the capacitor if I follow the above diagram is that the compressor came with a plastic cap that is supposed to cover the three terminals and the capacitor. The only way the capacitor will fit under it is if it is wired to the C terminal, due to how long the wire is.
This is the plastic cap I'm talking about

So I've got some conflicting information here, could anyone clear it up for me? For reference, the compressor's part number is 39R131F and its made by Rechi. It is 115 volt, 5238 BTU/Hr, and designed for R-22 refrigerant (if that's even relevant). I couldn't find any specs for it and Rechi's website had it listed but didn't have any info. Their site looks a bit dated. If anyone has any experience with these, I'd appreciate your help. Hopefully this will yield a new high pressure source.

ralphd · Fri Mar 27, 2009 6:55 pm

It's 115volts 60Hz 1 phase - OK for use in the states. It should weigh 6lbs displaces 7.75 cc's per revolution - 5238btu per hour - 620 watts.
"C" is common "R" is the run winding "S" is the start winding

Here is where I found the info....

http://www.rechi.com/en/web_en_products ... tegoryId=3

the capacitor does not go under that cap...what you are calling the capacitor is the overload. First place the rubber thing over the threaded post on the compressor so that the terminals fit through one of the two openings and it is flat on the compressor. Slip the overload under and through the rubber thing then connect the wire on it to terminal"C". The other terminal on the overload is where you hook your hot power wire. Your neutral wire goes to terminal "R". The capacitor is hooked up to "R" and "S".

I'm not sure what the other round thing is. If it has MFD on it then thats the capacitor. Hook it up like the first wiring diagram.

Whoops, first braze your pipes on to the thing before wiring it. The tube by the terminals is the output and the other tube on the tank is the input.

daberno123 · Fri Mar 27, 2009 7:40 pm

So this is actually the overload, not the capacitor? Or were you referring to the diagram? It reads B190-145C-241A on top, M603 on the side and 1188186 on the other side.

I tried hooking the compressor up like in the diagram and it ran (well more like buzzed) for a few seconds before I disconnected it because the wiring was pretty ghetto.

If you could just clarify on which is the capacitor and which is the overload that would be great.

ralphd · Fri Mar 27, 2009 8:44 pm

Yes, that thing, in the new pic above, with the wire is the overload. On the opposite side of it should be a dark disk that is recessed a little. That is the side that should rest directly on the compressor. As a matter of fact there should of been a small spring that fits around it while it's through the rubber piece. When you put the cover on, the spring pushes it so it stays in place. There should have been some paperwork with it which has the reccomended capacitor. ex. 25mfd @ 370volts. I should be like a small silver tin can with two terminals on top. Like this...

http://americanhvacparts.com/Merchant2/ ... Single.jpg

By the way, your drawing is correct.

daberno123 · Sat Mar 28, 2009 10:20 am

Great, I have no capacitor, and it didn't come with any paperwork suggesting which capacitor to use. I've contacted the eBay seller about it and I'll see if he knows anything about it. If not I'll try contacting Rechi about it.

@ralphd
Do you have any idea which capacitor is supposed to be used by this?

EDIT: I found the actual spec sheet in here, there's a link to rapidshare in the first post. The spec sheet calls for a 15uf/270 VAC capacitor but in that thread I linked to they said it wouldn't start with a 15uf one, but did with a 25uf one. I'm not sure which one to use now. Is there anyway using the larger capacitor could hurt the compressor?

TurboSuper · Sat Mar 28, 2009 11:06 am

May as well just get both; capacitors aren't horribly expensive. I don't think the 25uF cap would hurt the motor if it wouldn't even start with the 15uF one.

daberno123 · Sat Mar 28, 2009 11:09 am

Can I just use any capacitor for this, or does it need to be a special run capacitor?

I've been browsing some HVAC parts sites but can't find any 270 volt capcitors, only 370 and 440.

TurboSuper · Sat Mar 28, 2009 11:11 am

That's fine, the only disadvantage to using an over-rated cap is the size, really. Usually AC motors have big metal oval-shaped caps (they're unpolarized electrolytics, I believe). You'd probably want one of those.

daberno123 · Sat Mar 28, 2009 11:27 am

Thanks TurboSuper, I found one here on ebay. The only thing is that at $11 its more than half of what I paid for the compressor itself!

I'm going to keep looking and see if I can find anything cheaper. Does anyone know a good site for capacitors?

roughboy · Sat Mar 28, 2009 1:16 pm

dude,This is the same one i have.

daberno123 · Sat Mar 28, 2009 1:18 pm

How high have you been able to get it to pump? And could you check your capacitor to see if its 15uf or 25uf?

roughboy · Sat Mar 28, 2009 1:43 pm

the highest is 200psi but it can go much more than that. i checked the compressor, the capacitor and could not find any word saying 15uf or 25uf. how would i know if it's a 15uf or a 25uf?

c11man · Sat Mar 28, 2009 1:47 pm

so you are saying that these compressorst can pump up just as high as a fridgy or are you not sure?

roughboy · Sat Mar 28, 2009 2:04 pm

My gun's chamber can't go above 200psi thats why i stoped at that pressure. I asked the guy at the store where i bought it. How much pressure can this thing produce, the guy said, 300psi but as most of us know, fridge compressors and air con compressors can go way way more then the safety pressure stated on the lables.

daberno123 · Sat Mar 28, 2009 2:05 pm

@roughboy
The capacitor should say "xx mfd" on it.

@c11man
Hopefully just as high, since they are basically the same pumps.