Time to resurrect an old thread. After getting nowhere with that 5-2-1, and assuming it was bad, I exchanged it for a new one and just set the new one aside for them. I left the working kickstart in there, and it has been fine ever since. However, the fan stopped running and I found the dual run cap had died. No problem, put a new one in and all is well again. But since I was in there, I decided to once again replace that kickstart unit with the new 5-2-1. And once again, the compressor fails to start with it. I can not believe that I got two bad 5-2-1 kits.
As I mentioned nearly 2 years ago, these are pretty much fool proof to install. I just can not figure out why this particular compressor refuses to work with the 5-2-1. Now the wiring diagram does show a 2 wire kit (optional), so I don't know what to think.
This is not the first one I have installed. A color blind chimp could install it correctly.
Three wires all clearly color coded. Three connection points all clearly labeled. How can anyone possibly install it the wrong way? The only possible place I could see someone making a wrong connection is connecting the black wire to the same side of the contactor that goes to the common of the capacitor (i.e. actually connecting red and black together). And that is obviously not the case. For whatever reason, it just does not work on this unit.
BTW, the compressor will start just fine even without the 2 wire kickstart unit.
And before anyone asks, yes I removed the kickstart first.
What size capacitor did your 5-2-1 kit come with? I think they sell them in at least three sizes.
What size is the 2-wire kit's capacitor?
The 2 wire Kickstart is the KS1 model (3.5-5 ton) which has a 270-324uF cap. The 5-2-1 is the CSRU2 model (3.5-4-5 ton) and has a 189-227uF cap. Obviously they have different sized caps, but both are "supposed" to work with a 4 ton unit.
That's weird. I don't know why it isn't working. The only thing I can think of would be to try the 2-wire kit's capacitor with the 5-2-1 kit's potential relay and see what happens out of curiosity.
That's weird. I don't know why it isn't working. The only thing I can think of would be to try the 2-wire kit's capacitor with the 5-2-1 kit's potential relay and see what happens out of curiosity.
Something else I was considering, is that the Kickstart may be shot and is not even doing anything (since it starts just fine without it). And maybe this compressor won't work with either of them. That would also be puzzling, but would almost make more sense for neither to work, than for one and not the other.
I am probably going to just leave well enough alone (again), but it really bothers me when something as simple at this, does something totally unexpected.
No, I never checked the Kickstart unit. I just assumed it was working. The only reason I even considered replacing it was that so many folks seem to think the 5-2-1 is better.
No, I never checked the Kickstart unit. I just assumed it was working. The only reason I even considered replacing it was that so many folks seem to think the 5-2-1 is better.
Yeah, I never use those 2-wire kits. BTW, I think this is the video that philjafo mentioned in post #17 of this thread.
Matt Agee, that is one of the better,better, best ways that I've heard of to "remember" what is what,Tks.
Putting a female into the mix makes it work,LOL.
Lots of stuff wrong with that video. No modern AC is going to restart without a time delay, power outage or not.
As for not using the two wire, why is that the type shown on the manufacture's schematic?
The video has problems, but it does illustrate the undesirable temperature dependence of PTC devices. That's the main reason why I don't use PTC hard start kits. The rate at which PTCs heat up and cool down is largely dependent on how much current flows through them and on ambient conditions. The length of time they will keep the start capacitor in the circuit and take to cool down and reset is variable. It's just not an elegant solution.
Potential relays, on the other hand, will remove the start capacitor from the circuit when the compressor reaches a certain speed every time. There's no concern about the capacitor staying in the circuit too long and overheating (provided the compressor actually starts) or that the PTC will limit current through the capacitor because it's too hot.
With the advantages of a potential relay, the only reasons I can think of why a manufacturer would show a PTC on its schematic are cost and ease of installation.
Ok, I think I "might" have figured out the problem (or maybe just wishful thinking). I went back to take a quick look at the existing wiring again. Then I noticed that the switched side of the contactor was being used for the "black" wires (compressor/fan common) and the bus bar side was being used for the "red" wires (start/run).
I have no idea how long it's been like that, but probably at least 6 years or so. Maybe the guy who installed the kickstart also replaced the contactor and put it in like that. So under "normal" conditions or with using the two wire kickstart, having the contactor switch the common side would work just fine (as it obviously has been). However, since the 3 wire 5-2-1 uses that common line, perhaps it does not work because it is on the switched side.
To be honest, I am still having a hard time trying to understand how it would prevent it from working (it's still early and my brain is still half asleep), but that is the only abnormality I found with the existing wiring. Any thoughts as to if that would cause it not to work, and if so, why? The reason I don't understand how it could be the cause, is it would be no different than if someone just flipped the breaker on or plugged in the disconnect which would switch both legs. So it does not seem like that black wire of the 5-2-1 needs to be on the a non switched leg or it would not work if someone flipped a breaker on, etc..
Keep in mind everything else is wired correctly. The only discrepancy is which leg is getting switched with the contactor.
Ok, I think I "might" have figured out the problem (or maybe just wishful thinking). I went back to take a quick look at the existing wiring again. Then I noticed that the switched side of the contactor was being used for the "black" wires (compressor/fan common) and the bus bar side was being used for the "red" wires (start/run).
I have no idea how long it's been like that, but probably at least 6 years or so. Maybe the guy who installed the kickstart also replaced the contactor and put it in like that. So under "normal" conditions or with using the two wire kickstart, having the contactor switch the common side would work just fine (as it obviously has been). However, since the 3 wire 5-2-1 uses that common line, perhaps it does not work because it is on the switched side.
To be honest, I am still having a hard time trying to understand how it would prevent it from working (it's still early and my brain is still half asleep), but that is the only abnormality I found with the existing wiring. Any thoughts as to if that would cause it not to work, and if so, why? The reason I don't understand how it could be the cause, is it would be no different than if someone just flipped the breaker on or plugged in the disconnect which would switch both legs. So it does not seem like that black wire of the 5-2-1 needs to be on the a non switched leg or it would not work if someone flipped a breaker on, etc..
Keep in mind everything else is wired correctly. The only discrepancy is which leg is getting switched with the contactor.
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I know this is an old thread, but I'll try anyway. I am facing same issue with 5 2 1. What side of contactor does black wire go on? Switched or bus bar side? My bus bar side has black/blue wires and my switched side has red wires with one going to com on capasitor.
I know this is an old thread, but I'll try anyway. I am facing same issue with 5 2 1. What side of contactor does black wire go on? Switched or bus bar side? My bus bar side has black/blue wires and my switched side has red wires with one going to com on capasitor.
This is a DIY question and the forum rules do not allow us to assist with those type of questions.
Please call a contractor or visit a site that provides DIY assistance.
Thread Closed.
Instead of learning the tricks of the trade, learn the trade.