Compressor Wiring

[XC] gomeler · 12-04-2006, 07:28 PM

I finally got around to wiring up a unit based around one of the ebay rechi compressors and I have failed to get the compressor to start. The rechi only came with the thermal overload and after looking around XS I picked up a 25uF run capacitor and wired it up according to the wiring diagram. Besides the thermal overload and the run capacitor, do I need anything else such as a relay to get this unit running? The paint masterpiece below indicates the wiring diagram I found for the rechi, the bottom of the "power" is the black "live" line while the top is the white "common" line and I have the ground currently wrapped around the high-side copper line at the top of the casing. Am I missing something or was I sold a bum compressor? Let me know if more information is needed. Thanks in advance

runmc · 12-04-2006, 08:15 PM

your missing a wire

you need to run another wire from the R connector on the compressor to the same connector on the capacitor as the bottom wire coming from power source.

star882 · 12-04-2006, 08:17 PM

You forgot to connect the run winding. You might also need a start capacitor and relay. I'm not sure if 25uF is correct, so check the datasheet.

[XC] gomeler · 12-04-2006, 08:19 PM

Woops, mistake within paint, forgot to connect R to the live wire within the diagram. R is connected at the same junction as the capacitor on the live wire, essentially forming a Y. When I fire up the system it causes the breaker to trip so there must be a short within the system correct? Or would a locked up comressor draw too much current and short the system? Sorry about all the questions but I would like to avoid any accidents and attempt to get this thing working.

star882 · 12-04-2006, 08:25 PM

Yes, I suspect a short. A jammed compressor will simply not start and trip the overload protector in a few seconds.
Disconnect all the wires from the compressor and measure between the pins with an ohmmeter. If any show up unusually low (post readings first since they are generally low even when normal), the compressor is bad.
The hot wire should go to the common line but reversing the lines should not cause too much of a problem.

runmc · 12-04-2006, 08:26 PM

A picture would say a thousand words

[XC] gomeler · 12-04-2006, 08:46 PM

The picture with my thumb in the way shows the rat nest of wires attached to the plug for the wall. The jumble near my thumb is the live wire for the capacitor and the run coil, my index finger is the ground connection, and my middle finger is the common line. Anything look out of the ordinary? Capacitors can be wired any particular way? I've never had a capacitor require a particular direction in any of my labs so I figured these would be the same.

star882 · 12-04-2006, 09:02 PM

What happens if you disconnect the common wire from the compressor and try to turn it on? Does it still trip the breaker? What if you disconnected the S and R wires?

[XC] gomeler · 12-04-2006, 09:12 PM

I will go and experiment with it a bit, I wish I had a multi-meter on me, tomorrow I'll go out and buy one. Is it possible to run these systems w/o the run capacitor or will it damage the windings?

star882 · 12-04-2006, 09:22 PM

It just won't work. You might damage it if you leave it like that for too long, but testing for a few seconds shouldn't break anything.
But wait until you have the meter so you can actually measure.

[XC] gomeler · 12-04-2006, 09:25 PM

Well I just went out and played around with it, disconnecting the capacitor while leaving R and C connected caused the compressor to turn over for maybe 200ms before the breaker tripped, so either upon start it is pulling too many amps for the circuit or something else is wrong. Guess I'll wait till tomorrow when I have a multimeter and test the resistances between the points and see if there are connections. Is there any way to test if the capacitor is shot to pieces? Brand new from United but you never know.

edit: just rewired the entire setup to check for any shorts or non-connected wires, only improvement is that now the compressor makes the same buzzing noise for 100-200ms before cutting out, makes me think the compressor is locked up somehow.

edit 2: pretty certain this compressor was DOA but once I get a multimeter what should I check to see if it is dead or not, resistance between the coils and the common line? Thanks for all the help, looks like I'll have to find another compressor.

LukeXE · 12-04-2006, 10:48 PM

Try to connect it in that way, or maybe you did it already, but I don`t see that connection on photo with capacitor.

[XC] gomeler · 12-05-2006, 05:47 AM

With the 2nd setup the system trips the breaker immediately, with the first setup the system just sits there, buzzing away like when you hold a ceiling fan in place. Is that the sound of a bum compressor?

LukeXE · 12-05-2006, 05:55 AM

I think it`s dead :|

[XC] gomeler · 12-05-2006, 06:13 AM

Yeah, just what I was afraid of, oh well, $20 loss. Time to look for a new compressor, thanks for all the help guys

CWO4EVIL · 12-05-2006, 08:31 AM

ohm it out
Start to Run
Run to common
start to common and post #'s

_HL4E_HalfLife_ · 12-05-2006, 12:49 PM

Also see if u get a reading from the compressor housing to any of the 3 terminals ur MM should read infinite (no reading at all). A dead short would read as Zero.

Also Also do u have a start cap on hands? if so use the start cap in place of the run cap and just see if u can get the rotary up to speed. What i do when testing a compressor is i use a powerbar because i can quickly turn the power on and off and if a breaker trips it will be the one in the powerbar that trips first and not ur house breaker.So if that works to get the compressor going don't leave the power on for more than a few seconds because it will damage the compressor even more. If that works in getting it going take out the start cap and put the run cap back in and than power it up and if ur lucky it will start.

wdrzal · 12-05-2006, 03:31 PM

your original diagram shows you connected the white wire to the S & r terminals also.................... it should end at the C common terminal,.................thats what cased your breaker to Trip as that is a dead short.

the capacitor should still be ok ,but it could have been damaged if unit does not run check capacitor .

As long as you had a properly fused circuit the winding should not be damaged either, but that is also possible with a direct short. meter those for a short too. you can also check the ohms value and compare to compressor nomenclature.

wdrzal · 12-05-2006, 03:41 PM

wiring diagram you shouldn't neet the start capacitor circuit unless compressor calls for it

[XC] gomeler · 12-05-2006, 04:03 PM

wdrzal, thanks for the diagram. the white line is connected to the C on the compressor while the black line is connected to the S and indirectly to the R via the start capacitor. I didn't have a chance to get to a local shop to pick up a multimeter so I ordered one along with a Fluke 51 and a Kill a watt for kicks and giggles. New toys should be here in 6 days and I'll re-evaluate where I am from there. Also got a wicked deal on a cheap de-humidifier and I'm hoping to recover enough of the refrigerant in usable condition to use in the cheap single stage contest, would be excellent if everything goes correctly. Thanks for the help, once the multimeter gets here I"ll check the resistance and see if I can revive this compressor, otherwise I'll have a similar rotary to use. Thanks for the help guys, just plain bad luck is all.

wdrzal · 12-05-2006, 05:29 PM

there are 4 compressor types, that diagram or part of it covers 3 of them while the 4th uses no capacitors at all.

you probably have a psc compressor out of a a/c unit and does not need the start capacitor or relay. only run capacitor ,but need compressor info to confirm that.

1: no capacitors
2:run capacitor only
3: start capacitor only
4 capacitor start,capacitor run.

the appropriate relays are also needed.

PS: Bad luck has nothing to do with your problem, you proceeded as many do without the proper knowledge and information putting yourself and home and family in a dangerous situation, you NEVER GUESS when wiring something. You MUST know for sure,or don't proceed. only a a circuit breaker prevented the wires from turning red hot and possible starting a fire or electrocuting you.

a fluke 16 would serve you better as it is a multimeter, reads capacitor uf/micro-farads and has a type K temp probe ,great first meter for guys doing phase.they are relatively cheap around 100.00 seen new ones on ebay for 70.00 and used even cheaper. Also buy a good book,9/10 of what you need to know is not even talked about on forums.

[XC] gomeler · 12-05-2006, 08:51 PM

I haven't been doing this blindly.. I know you preach safety as I've been on this forum for more than a year. Here are the only specs for this relatively no-name compressor company, unlike other companies there is zilch for documentation in regards to this compressor.
http://www.rechi.com/e-prod-39.htm
The compressor is a 39R131F and considering how the website looks extremely dated I'd wager they simply revised the product lines and let the website linger. The reason why I have had so many "noob" questions is the fact that I've never had to wire a compressor with so little information, usually I had proper wire diagrams and industrial examples to follow. In regards to your suggestion for a temp probe/multimeter etc, I'll look into it, thanks for the advice.

One last note about safety, while the circuit breaker on the wall was tripping after less than a second, the entire time I saw there with a power strip with a huge button under my foot so that if something when haywire I had the option to kick the strip and kill power to the circuit. I understand the power of alternating current and I know it takes less than 110 volts to kill a person but if care is taken and respect is given to its killing properties, it is possible to work with it. I always use a single gloved hand when wiring compressors to keep from shorting a circuit and shorting my heart, this is just my first compressor that has given me such a problem, I've never had a compressor be DOA or die on me so I didn't know the signs.

wdrzal · 12-05-2006, 09:36 PM

The 2 diagrams shown on that site are the same as I gave you except the diagram I gave you shows a capacitor start ,capacitor run setup. if start capacitors are not needed you just don't use the relay and start capacitors.

Your mistake is you didn't realize the loops in the diagram on that website ,just as the VVVVVV waves are in my diagram are not external connections and are the electrical symbols for resistance/windings that are internal .

[XC] gomeler · 12-05-2006, 10:04 PM

Errr yeah, that was one of the first things I noticed along with the fact that they are the same symbols used in my classes for inductors so I figured they represented the "S"tart and "R"un windings along with the "C"ommon line. That was one of my first observations with compressors, those letters weren't randomly chosen by the founding fathers of compression. Either way I'm writing off the compressor at DOA as even when wired correctly and checked by my friend to ensure I am following the diagram correctly the system creates a lovely buzzing sound which reminds me of the noise large ceiling fans make when they encounter resistance/heads. Now I have a lovely paperweight/door stop, a story and I picked up some valuable information along the way.

wdrzal · 12-05-2006, 10:33 PM

Like I said, if the breaker kicked chances are the internal windings are ok, you may have blown your capacitor,you need to check that you have the correct uf and its not shorted.