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FIXED FAS257S2A Frigidaire AC - HARD STARTING again - Maybe lightning damage....

cwatkin

Premium Member
Joined
Jul 23, 2017
Messages
45
Location
MO
Model Number
FAS257S2A
Brand
Frigidaire
Age
More than 10 years
OK, this unit has been a repeat offender before so maybe it is giving it up for good. It was posted here in the past. https://www.applianceblog.com/mainforums/threads/61662-FAS257S2A-25-000-BTU-Window-AC-unit-diagnosis-capacitor-or-compressor?p=312937#post312937

Anyway, the short story is that this unit came to me with my current place. I use two large 25,000 BTU units to keep my place cool. Both are Frigidaire (slightly different models but basically the same). I replaced the caps in both last year.

The unit in question has been a hard starter since I moved in during the spring of 2011. Tripped breakers were pretty much the norm. It was maybe 2-3 years old at that time. The other unit never acted up until last year and a new cap solved that. In the end both began humming like they were locked up and kicking the overload relay out over and over.

So, the unit in question was fixed by replacing the cap. It never tripped the breaker or gave me any more grief for the remainder of last year. It couldn't go two weeks without tripping the breaker in the past and towards the end it was about every other day. I replaced the breaker thinking it was weak but that wasn't it. It was the cap.

Then a week before this Memorial Day, I took a nasty lightning hit. Most of my sensitive electronics are on pretty heavy duty protection so they survived. My electric fence charger went BANG like a gunshot and was toast of course. I thought that was the only casualty until my well quit two days later. This had happened once before and I got away with replacing the control box which consists of a relay and capacitor. This didn't work so I called a well company and they were able to show up that day. The well pump was bad but they were able to get it running by wiring it directly into the 200 amp service. They said they would be back in a few hours but just to leave the water running as the pump might not turn back on. I ran a hose off the hydrant out into the yard and just let it run. They came back and replaced the pump a few hours later.

So, I leave the for the weekend over Memorial Day and I come home to only one of the units functioning. I checked the breaker and it was tripped so reset it, hoping it was a fluke. All was well until this morning when I turned the unit back on. It hummed like the compressor was frozen and then the breaker tripped. I reset the breaker and it came right back on. I turned the temp down low so it wouldn't cycle on and off and it was still running fine and cooling when I came home 10 hours later. I had turned the other unit up so it would only come on as a backup if the breaker tripped and my place wouldn't get too hot and fry my inside cats.

The unit has continued to cycle normally tonight. I am wondering if I should just replace the cap again and see if that helps, get a hard start kit, or just consider it junk and run it until it fails. I happen to have a spare cap on hand. The spare as well as the one in the unit are both made by SUPCO. I see it is made in China but the local supply houses all sell them and say they are OK parts for what they cost.

I think the cap cost me $14-15 and I have one on hand. I think the hard start kits the local supply houses have are about the same price. The unit would cost $600 to replace so I don't mind spending a few bucks even if I only prolong its life through this summer or so. Remember this one has been a hard starter since the beginning so maybe it was defective. Any advice would be appreciated.

Conor
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
43,698
Location
Murray, Utah 84107, United States
A hard start is a start capacitor with a solid state relay/overload. It's been my experience once you start using a hard start on a compressor, the end is near. How many amps is the compressor pulling during start and during run?
 

cwatkin

Premium Member
Joined
Jul 23, 2017
Messages
45
Location
MO
I am about to borrow a clamp meter

A hard start is a start capacitor with a solid state relay/overload. It's been my experience once you start using a hard start on a compressor, the end is near. How many amps is the compressor pulling during start and during run?

I am going to borrow a clamp meter from a retired HVAC tech I know and will report back with some numbers.

This is a 25,000 btu unit so is basically a 2.1 ton unit from what I understand.

Remember that this has been a hard starter since I became the owner in 2011. Intermittent breaker trips have been the norm with maybe 1-2 a month. It definitely got worse right before I replaced the cap and then didn't trip at all for the remainder of last summer.

If I want to keep this running, would you avoid use of a hard start kit, maybe just install the new capacitor, and see where things go from there? Is a hard start kit like dumping that liquid glass crap into an engine to plug a head gasket leak instead of fixing it right? That is fine for a junker car you want to limp along a few months at most but you wouldn't want to do it if you intended to fix it correctly. Does this get the compressor going but at the expense of its remaining life? In my case it is starting but there are intermittent trips of the breaker.

I know this is just a window AC and I wouldn't pay to have it professionally serviced, especially at this age, but it isn't a cheap unit to replace so want to prolong its life if I can.

I will get some numbers with the amp meter and report back.

Thanks,

Conor
 

rickgburton

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As the compressor wears down the resistance of the start windings and run windings decreases. Ohm's Law says as the resistance decreases the current increases. Over time the capacitance of the capacitor drops with use. The start capacitor is only used to start the compressor when both run and start windings are energized. Once the relay switches over to just the run windings the start capacitor is dropped from the circuit. If the unit is running and lightning strikes the unit, the start cap wouldn't be affected.

That being said, whatever is on the same circuit as the AC unit is added to the current total. It's not uncommon to see a current spike of 20 amps when the compressor starts. Once the compressor reaches 75% of it's normal operating speed the relay switches over to just the run windings and the current drops. The longer it takes to start the more chance the breaker will trip. Some older houses have 15 amp breakers instead of 20 amp breakers.

There's too many factors to consider to be able to tell you if a new capacitor or a hard start will extend it's life or hurry it along.
 

cwatkin

Premium Member
Joined
Jul 23, 2017
Messages
45
Location
MO
I see. I have the clamp meter in hand and will report back with the numbers once I get to it.

My main concern is that the hard start may shorten the life. I would rather deal with intermitten breaker trips than not have them and fry the unit in two weeks. Is this a possibility. If the unit is about to take a dump, I don't care but if this will hurry it along to the scrap heap, I would rather just replace the cap.

This is considered a "run capacitor" from what I understand so stays in the circuit. The hard start kit is a start cap with a relay.

I will check the amps soon and report back.

Conor
 

cwatkin

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Joined
Jul 23, 2017
Messages
45
Location
MO
OK, I just pulled the front of the panel off and used the thermostat to force it to cycle a couple of times. The first time the start amps were like 32. The next time it was like 24. This was very momentary and then it settled down to around 7 and slowly rose to around 8.5 and stabilized. The other basically identical unit was running at the time and it was also pulling 8.5 amps running. I did not check the start amps just yet but will do so after I eat dinner. This is a nice comparison since it isn't popping the breaker.

Conor
 

cwatkin

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Joined
Jul 23, 2017
Messages
45
Location
MO
I read the amps on the one that isn't popping the breaker again. They were up to right at 11 or a tad below while it was running. I forced that one to cycle and the startup peak was basically nonexistent. It just turned on and the amps rose slowly from there. The lights didn't dim and there was no buzz/hum from the panel.

Another interesting thing is that you can hear a definite buzz or hum from the breaker or panel when the offending unit starts. The peak amps are extremely momentary and the hum is much the same. I mean less than a second and probably less than 1/4 second.

These two units are quite similar but one is pulling a LOT more at start. Both had failed capacitors and I did replace the capacitor in the other unit of course. I looked up the specs and seem to recall that they both have the same exact compressor one using a significantly larger run cap (~25% larger for the compressor) than the one that is flipping the breaker. I am wondering if that was a different revision and that they realized there was a problem and needed to upsize the cap. The one in the unit flipping the breaker is a 40 mfd. I seem to recall the other cap is a 50 mfd but am not sure. I am half tempted to just get one of those but want opinions first. I simply used one with the same specs as before and am now having the same problem.

Would you suspect a compressor getting tight or a bad cap with these huge startup current draws?

Conor
 

rickgburton

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I agree, if they are the same compressor and btu's, go with the larger cap. A run cap isn't necessary for a compressor to operate correctly. It's only purpose is to help the compressor run more efficiently.
 

cwatkin

Premium Member
Joined
Jul 23, 2017
Messages
45
Location
MO
I will go with the larger cap and see.

I agree, if they are the same compressor and btu's, go with the larger cap. A run cap isn't necessary for a compressor to operate correctly. It's only purpose is to help the compressor run more efficiently.

They are a tad different model but the compressor is the same and the cap is larger and I always thought that was the strange thing. I work on computers for a living and often see changes within different revisions of the same model. Sometimes these revisions are minor and improve performance or efficiency ever so slightly and the average user wouldn't have a clue. Other times they fix a major bug or other issue and I suspect that might be the case with these two units.

Anyway, I will get the same 50 mfd cap used in the other unit and see what happens.

Conor
 

cwatkin

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Messages
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Location
MO
I just checked to make sure but the other cap is a 55 mfd. This one has never had an issue. The other came with a 40 mfd and has been a hard starter all its life and uses the same LG compressor.

I will report back and take amp readings as well.

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cwatkin

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Jul 23, 2017
Messages
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Location
MO
Anyway, here is the update. I went by the supply house and purchased the same 55 mfd capacitor used in the other basically identical AC unit.

The unit kicks right on with a lot less noise and sounds a lot smoother.

The amp draw curve is basically the same as the other non-problematic unit and a tad lower than with the other capacitor (40mfd). The unit kicks on and is pulling about 7 amps as soon as it starts and it runs up to around 10 amps after several seconds. This is a little lower than it was running with the 40 mfd cap so this tells me it is running more efficiently and that the factory specified cap (40 mfd) was likely quite undersized. It is a smooth start to about 7 amps and then gradually climbed a few more amps. There is no huge amperage spike at start anymore as there was with the other capacitor when it peaked at 24 and 32 amps the two times I tested the start amps prior to the capacitor replacement.

I purchased a hard start kit but it remains in the package and I plan to return it to the supply house as I don't think it will be needed.

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cwatkin

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Messages
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Crap like this is why I hate big box stores. Both these units were purchased at Lowes by the previous owner. Remember that I work on computers for a living. I commonly see units sold at Wal-Mart and similar that are so under-spec'ed that they are basically unusable from the time they are removed from their box. So many corners are cut so they have a lower purchase price but are junk right from the start.

I see 40 year old window AC units in places that look like they have been to war and they still run and cool well.

I also just talked to the previous owner and the one that was giving me troubles was purchased first, but only be a couple months or so. I suspect a lot of warranty claims were being made due to the undersized caps and they upgraded that component in the newer models.

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rickgburton

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Sounds like you found the problem and corrected it. When I have a service call on an appliance that has never been worked on before I assume the manufacturer used the correct parts. I always ask if the appliance has been serviced before and what was done. If it's been serviced before that's the first thing I check to see if it was done right. Hopefully it will keep working for you without anymore issues.
 

cwatkin

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Jul 23, 2017
Messages
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Location
MO
We will see after a month or so. It seemed like it would always pop the breaker once or twice a month in the past. I will think it is solved after seeing it not flip for a couple months. I am guessing it was on a fine edge of tripping the breaker each time it kicked on with those current draws. The capacitor seems to be doing what it is meant to do. It provides the sudden surge of power needed to start the compressor and isn't producing ANY noticeable surge of amps at the service panel.

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cwatkin

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Messages
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Yes, I would have assumed that the manufacturer had used the correct parts as well. I find it funny that the unit had been giving me the same problems for years and suddenly its behavior is matching that of the unit that is not giving me troubles and only did once when I had to replace the cap on it as well.

Remember I replaced the cap on this last summer and got it going but I guess that cap was probably overstressed and getting weak from being undersized.

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cwatkin

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I wanted to give an update. The unit appears to be operating much better. I returned the amp meter to its rightful owner but I conducted several more readings and they were all much better than before. Again, the lights are not dimming and there isn't a hum from the panel when it kicks on.

Something else I found interesting is that I didn't realize the blower fan was on the low setting. The compressor was continuing to cycle even during the recent extremely hot days with the temp turned way down. This is one of those fans where the blower and the condenser fan operate off of a single motor with a double-ended shaft. I guess that the compressor is sized to where it was dissipating more heat than the fan could remove so was cycling. I turned the fan speed up and the cycling has greatly reduced.

I found an EPA site that suggested running the fan at max for best efficiency but said that running the fan at a slower speed is best for conditioning the air as moisture better condenses on the cooler coils and is removed by dripping. I think that on hot days I will keep the speed up and when it isn't so hot, I will run the fan on low.

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