Installed an AC Hard Start Capacitor - Definitely recommend!

[lugoismad]

I replaced the small black capacitor on the left side

With this http://www.amazon.com/SUPCO-SPP6-Start-Relay-Capacitor/dp/B0002YTLFE

When the Compressor kicks on its no longer a lights dimming amp sucking situation.

Before, when I would try to start the AC just using a small 15 amp extension cord, I'd pop a breaker because it was pulling so many amps to start the AC.
Now, it starts right up with no issues, because the start amps have been reduced because it has the juice it needs in that capacitor to get it going.

This mod took me all of 20 minutes. Cover off the AC. Find the start cap and the black thermistor thats the round sideways object you see above it, remove both, install new hard start cap. It doesn't matter which way around you install it. You just unplug the old stuff and plug this in where it was at.

 

[JimmyM]

Before, when I would try to start the AC just using a small 15 amp extension cord, I'd pop a breaker because it was pulling so many amps to start the AC.
Now, it starts right up with no issues, because the start amps have been reduced because it has the juice it needs in that capacitor to get it going.

That isn't quite how it works, but the end result is the same.
The capacitance balances the inductance in the power factor increasing the available watts per VoltAmp.
In DC circuits Volts * Amps = Watts. In AC circuits, Volts * Amps * PowerFactor = Watts. With a higher power factor, you draw fewer amps per Watt delivered. Thus allowing the compressor to start more easily while drawing fewer amps. Ta da!

 

[CREEPPINGCHARLIE]

Lugoismad

How about an after picture on install or a wiring diagram. This mod is very interesting.

 

[lugoismad]

Lugoismad

How about an after picture on install or a wiring diagram. This mod is very interesting.

Replace the black cap and the black thermistor above it with the new cap. Plug it in where those are plugged into the silver cap next to it. Polarity doesn't matter.

Sorry no after pic, my phone died.

 

[PhillyTitan]

lugoismad, The startup on my A/C's compressor is particularly severe on power drain on both the AC and DC power. So, I'd like to try this mod also.
Is this cap in parallel with the main 110VAC circuit or in series with the circuit that serves the air conditioner?

 

[lugoismad]

lugoismad, The startup on my A/C's compressor is particularly severe on power drain on both the AC and DC power. So, I'd like to try this mod also.
Is this cap in parallel with the main 110VAC circuit or in series with the circuit that serves the air conditioner?

I honestly don't know. I just replaced the old with the new.

 

[Dirtydozn]

I know this is a old thread but I just had to weigh in. I am new to the sight and pop up but I have been an a/c tech for 15 years. did you check the gray capacitor as well you are probably having an issue it that style cap goes bad quick. also the style of start cap you put on are compressor killers. you want to purchase one that has a separate relay that goes with it you might spend a few more dollars today but save a lot in the future. take it from me I have seen a lot of those start caps kill compressors over the years any questions let me know

 

[jman1200]

Dirtydozn, can you post a link for the type you would recommend?

 

[JimmyM]

I know this is a old thread but I just had to weigh in. I am new to the sight and pop up but I have been an a/c tech for 15 years. did you check the gray capacitor as well you are probably having an issue it that style cap goes bad quick. also the style of start cap you put on are compressor killers. you want to purchase one that has a separate relay that goes with it you might spend a few more dollars today but save a lot in the future. take it from me I have seen a lot of those start caps kill compressors over the years any questions let me know

Thanks for posting. What they want is a potential relay. There are kits out there that have them. But you're right. They're more expensive. But worth it.
Also a larger cap is not a better cap. I've seen people suggest a bigger cap will deliver more energy than a small cap.
In these installs the cap is not storing energy like a DC system would. It's there to change the phase angle of the power at the start winding. If you don't understand how capacitance changes the properties of an AC voltage/current, stick to the manufacturer recommendations.

 

[JimmyM]

Here's one for Dometic specifically.
http://www.adventurerv.net/quick-start-kit-p-15783.html

Here's a link showing how to wire it in.
http://www.gmcmi.com/wp-content/uploads/2014/05/Quick-Start-Kit.pdf

 

[adrianpglover]

Thanks for posting. What they want is a potential relay. There are kits out there that have them. But you're right. They're more expensive. But worth it.

So I'm confused here. The OP's AC unit originally came with both a run capacitor (the grey/silver one) and a start cap (the black one). It also had a PTCR (the sideways black cylinder). The OP removed the start cap and the PTCR (Positive Temperature Coefficient resistor controlled Relay) and replaced it with a Supco brand SPP6. According to Supco's website the SPP6 is a single package that both includes a start capacitor (in the range of 130-156 uF) and a PTCR. How is this different from the one that he removed?

I am new to the sight and pop up but I have been an a/c tech for 15 years. did you check the gray capacitor as well you are probably having an issue it that style cap goes bad quick. also the style of start cap you put on are compressor killers. you want to purchase one that has a separate relay that goes with it you might spend a few more dollars today but save a lot in the future. take it from me I have seen a lot of those start caps kill compressors over the years any questions let me know

I agree that if the start cap was bad, the run cap is probably also bad. Wet caps tend to dry out as they age, heat and exposure contribute to this. As an EE I've had to replace a lot of wet caps in test equipment at home. At work they give us much nicer tools to use than I'm willing to buy for myself.

also the style of start cap you put on are compressor killers. you want to purchase one that has a separate relay that goes with it you might spend a few more dollars today but save a lot in the future. take it from me I have seen a lot of those start caps kill compressors over the years any questions let me know

Is there something inherently wrong with the packaging? I'd think it'd be more brand or price category specific than just the bundling of them together.
Is it that you've seen these smaller ones installed on larger household units and had it kill them? If that's the case then they were probably undersized and didn't do what they were supposed to do.
Or is it more that the OP should have used something like the Supco SPP6E that has a start capacitor and PTCR that contains a timing circuit to trip the relay in case the PTC doesn't do it at the right time?


I'm sorry for all of the questions. I don't doubt anyone's knowledge here. It's just I'm a EE who works in power design, mainly lower voltage DC systems, but am interested in knowing the justification behind the positions that both of you have taken here. Also, I have an Advent Air 15kBTU unit on my camper that didn't come with a start cap, only the run cap (which may be a combination run/start, but I'd have to dig up a schematic). I have no issues with mine starting, but if I can add something to make it work less hard and extend it's life, then I'd like to know about it and know how to go about choosing the parts.

 

[Dirtydozn]

there is a lot to respond to. always use the size run cap the manufacturer originally puts in the gray one in this case. aftermarket start caps unfortunately do not come in the proper mfd rating as an original start cap. carrier used that little resistor cap for years its a different type of starting style. if your unit did not come with a start device such as the start cap and relay like the black one in this case unless you are having a problem with start up do not install one of these the windings in the compressor were not designed to start that way for prolonged periods of time. they will help you get by for a while until the compressor finally dies. if you have a start cap and it dies try to replace it with as close to manufacturer specs. a typical error of installing the suppco is the placement of the cap/ relay make sure it is upright. also in my experience the cheap relay that suppco fails closed and cooks the windings in compressor. again if your unit did not have one of theses unless your having a problem do not install. on these caps there are a few different sizes based on the capacity of the units from1-5 tons they are set up as a general ranges sometime s it may be to much or to little for the unit suppco does not know what is required for every different unit out there so it may be to much or to little both can hurt a unit. if you have one cap in your unit with three terminals it starts both the outdoor motor and compressor you do not need a start cap the comp was not designed to take one only use if your having a problem. now having said that there are some units that can take one cause the manufacturer took out start cap to save money on lower seer units but the unit can take a start cap. most trane American standard require a start cap they will not start without it also only use trane start caps for a tranethe brand I use is 5-2-1 compressor saver only in last resort situations get the manufacturer stuff its rated correctly for the application

 

[adrianpglover]

Thank you for the detailed explanation. For my unit I'd have to go open it up to see how it was wired. Also I might check if the unit has a label on the compressor that would give me enough information to run a spice simulation, but I doubt I'd find that.

 

[real lite virgin]

Thanks for all the information guys

 

[adrianpglover]

Sorry I didn't completely clarify my comment about running a spice simulation. In college (~10 years ago now) I took a course called "Electric Drives and Machines" as a senior elective. The professor would routinely show us spice simulations and models for all types of single and three phase AC motors during normal run conditions, varying load conditions, and during startup. The course was also offered as an online course so every lecture was videoed. All the simulations, problems, videos, and other resources were made available online and I made sure and had a copy of them before I left there. He had also at one point made the statement that "all" AC motors have a label on them with just enough information about them so that they could be modeled or the equations could be run through by hand. My thought here was that if I can find such a label on the motor for my unit, I might be able to dig up either the simulations or at minimum find the chapter in the textbook discussing the start capacitors and see if the manufacturer included a start capacitor or not.

Being that these units are quite often cheaply made and some, like mine, are sold fairly cheaply, in addition to the fact that it's basically a window AC unit in a different form factor, I wouldn't be at all surprised if the manufacturer cut some corners in order to make more profit.

I completely agree with Dirtydozn's comments that if you don't know what you're looking at or haven't gone through all of the necessary research, just making a change to an electronic circuit can very easily cost you more in the end, not to mention the potential for fire and loss of the entire unit.

 

[bupkis]

rvp/coleman has a good document library

http://www.airxcel.com/coleman-mach/service-support/document-library
http://old.rvcomfort.com/rvp/pdf_documents/1976136.pdf
http://old.rvcomfort.com/rvp/pdf_documents/8333data.pdf

generator users often find the need of the optional start cap.
the additional torque can allow the a/c to start.

 

[Dirtydozn]

there is a very big problem in my industry where very uneducated techs are selling things that do a lot of damage. I cant count the number of times I have had to teach Walmart and car salesman how to fix a/c's these big companies don't want to pay good techs what there worth so they hire idiots trane them for two weeks and have them try to sell products you don't need. it very disappointing that is why I am in business for my self. I cant count the number of times I have been asked to go behind a tech that missed wired something and blew up a unit aaahhhh. just last week atech from a company called George brazil by the way is way over priced told customer his compressor was bad not the cae just a bad fan motor comp was out on ip (over heated) they wanted to sell him a new unit at8000.00unit was 7 years old just replaced motor for250.00 back up and running by the way this was a vet on disability missing the use of one of his legs for shame thanks for listening just drives me crazy

 

[Dirtydozn]

the compressor will only give you the size of the run cap maybe schematic would tell the size of the start cap you would need to get ahold of tech support for manufacturer for more info. call the local dist for the equipment and talk to there tech person may take a couple phone calls but they are always willing to help

 

[adrianpglover]

So for the Advent Air models I know they make/made a kit that included a separate relay and start cap. The pictures in the manual are high enough resolution to tell that they were using a SPPBL37 for the relay and a 43-35 uF capacitor for the start cap, at least for the instruction manual. The manual also shows the main cap as a 60+5 uF, which I would assume is 60 uF run and 5 uF start, but I may have this backwards. The kit is hard to find or unavailable now, which is why I was looking at the combined relay/cap kits. I haven't opened up the panel on my unit in a while, but I do remember that there's only the silver cap in mine. Again, I'm not running into issues, but I typically make sure I only have strong connections to good clean power when I use it.

 

[turborich]

OP:
Before, when I would try to start the AC just using a small 15 amp extension cord, I'd pop a breaker because it was pulling so many amps to start the AC.


You should NEVER run your A/C with a 15 amp circuit with an extension cord. This is real issue, not the capacitor. Always use a 30 amp cord and a 30 amp outlet.