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Residential Split R-22 System Extreme Short-Cycling

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Freon Russell

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Discussion starter · #1 ·
Hello, all. What an interesting forum. I tip my hat to those who slog through often-miserable conditions to keep us from roasting half to death.

My neighbor's unit suddenly started extreme short-cycling when we did a winter tune up on it during a warm day last month. Less than a minute on, then shuts off, then restarts, then shuts off after about 10 seconds, repeat......

Changed contactor and cap, new filter, blower motor is strong and was replaced last year, fan is good, bypassed old school Honeywell digital thermostat with no changes, low voltage is steady, TXV, coils always kept clean, 5" Skuttle filter, very reliable system that was installed well and diligently cared for.

Both sides at about 125 psig at rest.

At startup low side quickly drops in about 30 seconds to 25 psig while high side increases to 160, then low pressure shutdown triggers.

After shutdown, low side increases to 55 over about 10 seconds, unit restarts, cycle repeats - low side back down to 25, high back up to 160, shutdown. There is heat exchange occurring at the condenser. Pressures on both sides equalize into the 120s soon after shutdown and rest.

This dear lady is an elderly widow without a whole lot of spare change, so I'd like to help see to it that she gets the best result possible. Obviously, a new system looms at some point, but hers is so clean and nice and has been so reliable that we'd love to see it roll on a bit longer if practical.

Much obliged and best wishes.
 
#2 ·
Freon Russell said:
Hello, all. What an interesting forum. I tip my hat to those who slog through often-miserable conditions to keep us from roasting half to death.

My neighbor's unit suddenly started extreme short-cycling when we did a winter tune up on it during a warm day last month. Less than a minute on, then shuts off, then restarts, then shuts off after about 10 seconds, repeat......

Changed contactor and cap, new filter, blower motor is strong and was replaced last year, fan is good, bypassed old school Honeywell digital thermostat with no changes, low voltage is steady, TXV, coils always kept clean, 5" Skuttle filter, very reliable system that was installed well and diligently cared for.

Both sides at about 125 psig at rest.

At startup low side quickly drops in about 30 seconds to 25 psig while high side increases to 160, then low pressure shutdown triggers.

After shutdown, low side increases to 55 over about 10 seconds, unit restarts, cycle repeats - low side back down to 25, high back up to 160, shutdown. There is heat exchange occurring at the condenser. Pressures on both sides equalize into the 120s soon after shutdown and rest.

This dear lady is an elderly widow without a whole lot of spare change, so I'd like to help see to it that she gets the best result possible. Obviously, a new system looms at some point, but hers is so clean and nice and has been so reliable that we'd love to see it roll on a bit longer if practical.

Much obliged and best wishes.
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Who performed the tune up? You need a tech on site with gauges to verify the issue. Sounds like 2 possible problems, should be easy to find. Let us know what the tech finds.
 
#3 ·
What are you calling a warm day in February? Here anything over 50 degrees even at the end of February is considered warm but 50 is too cold to run an A/C unit especially residential and get any meaningful results.
 
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#4 ·
The most likely cause is low on refrigerant. But there are a few other things that can cause the same results/symptoms. Making a call for a one hour service call would be plenty of time for even an average tech to determine / verify the actual problem, that would give you a baseline to work from and make further decisions.
 
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Discussion starter · #5 ·
Thanks for the reply, My uncle and I have done the tune-ups on it since the beginning and we assisted in the installation. I'm EPA 608 Universal cert and 609 tech and he is a licensed HVAC contractor who is now laid up, perhaps permanently, due to spinal problems and can't participate any longer. I used to be his apprentice, but moved on to other things after a couple of brutal attic jobs.

So, those data were obtained by a tech on site with gauges. At least kindasorta. The unit has received exemplary care.

The two possible problems seem like a blockage or just plain low charge. We're hoping for the latter ;)
 
Discussion starter · #6 ·
BNME8EZ said:
What are you calling a warm day in February? Here anything over 50 degrees even at the end of February is considered warm but 50 is too cold to run an A/C unit especially residential and get any meaningful results.
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Hiya there! Indeed, 50 would be too cold. This would be ambient 74-78F when those pressure readings were taken.
 
Discussion starter · #7 ·
Yep, that seems to be the case. I'm about to go over there and do a more thorough visual check than I had the time for earlier.

I hear ya, but she ain't gots the dough right now for the service call. She's waiting for some dividends to drop and a CD to mature next month, but is quite worried about the matter and is trying to get a leg up on knowing what the range of scenarios is so she can steer her life accordingly. My uncle - a now gimpy and likely retirement-bound HVAC contractor - and I have been looking after her at no labor or spare parts charge for years, but he's out of the picture now and I've been out of the trade (actually, I prefer the term "industry" or "profession") for a good while.

I do have quite a bit of experience with residential and MV HVAC and am 608 + 609 cert.
 
#8 ·
BBeerme said:
The most likely cause is low on refrigerant. But there are a few other things that can cause the same results/symptoms. Making a call for a one hour service call would be plenty of time for even an average tech to determine / verify the actual problem, that would give you a baseline to work from and make further decisions.
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He's from east Texas, the chances of getting someone out for less than $300.00 service call would be hard to do, and if he did, he would probably know more than them. :grin2:

.
 
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Discussion starter · #9 ·
Mr Bill said:
He's from east Texas, the chances of getting someone out for less than $300.00 service call would be hard to do, and if he did, he would probably know more than them. :grin2:

. View attachment 887253
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I hate to say it, but that's a reasonably accurate statement. Heck, even a tire installation at Walmart last week turned into a fiasco when the clod installed unidirectional tires backward, then insisted it didn't matter. Had to raise a stink to get it done right. Lots of family trees that, uh, don't branch enough out that way, if'n ya catch my drift ;)
 
#10 ·
Freon Russell said:
I hate to say it, but that's a reasonably accurate statement. Heck, even a tire installation at Walmart last week turned into a fiasco when the clod installed unidirectional tires backward, then insisted it didn't matter. Had to raise a stink to get it done right. Lots of family trees that, uh, don't branch enough out that way, if'n ya catch my drift ;)
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Ask me how I know? my sister lives in Livingston. :grin2:
 
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#11 ·
If it a low charge, they need to do leak search, and repair the leak. In my area that usually involves replacing the evaporator coil. If it is not low charge, would suspect a possible valve replacement. Either way is could be 1/4 to 1/2 the cost of a new system. Good luck.
 
Discussion starter · #12 ·
Mr Bill said:
Ask me how I know? my sister lives in Livingston. :grin2:
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'Nuff said. We're deeper east where things can REALLY get.....interesting.

Lots of big time solid people out here, for sure, but the fiasco machine - that invisible thing that can make matters go incomprehensibly sideways amid a stark paucity of due cause - runs on turbo out here.

I must say, though, that I wasn't quite accurate about us not getting paid by the sweet ol' dame we're trying to help - she's paid us every time with the best fried chicken, mashed taters, and sweet tea ever I've beheld along with stellar conversation and regard for local history. And, she's just plain cool, esp for someone born in 1934.....but not for long unless we get this done.

I badly hope she can outlive that Copeland scroll compressor outside her bedroom window and I'll do what I can to help her fare as well as possible in this matter. And, here we are.

And get this - one of her neighbors, whose unit we also took care of, is still using the same system from when the house was built in 1963. The thing was delivered in a horse and wagon. It works adequately, but I've a hunch that a replacement is imminent in the next ten or twenty years. That owner is a hoot, too - the R-22 system was a marvel to them back then 'cuz of its lack of inclination to poison or explode :eek2:
 
#13 ·
Freon Russell said:
'Nuff said. We're deeper east where things can REALLY get.....interesting.

Lots of big time solid people out here, for sure, but the fiasco machine - that invisible thing that can make matters go incomprehensibly sideways amid a stark paucity of due cause - runs on turbo out here.

I must say, though, that I wasn't quite accurate about us not getting paid by the sweet ol' dame we're trying to help - she's paid us every time with the best fried chicken, mashed taters, and sweet tea ever I've beheld along with stellar conversation and regard for local history. And, she's just plain cool, esp for someone born in 1934.....but not for long unless we get this done.

I badly hope she can outlive that Copeland scroll compressor outside her bedroom window and I'll do what I can to help her fare as well as possible in this matter. And, here we are.

And get this - one of her neighbors, whose unit we also took care of, is still using the same system from when the house was built in 1963. The thing was delivered in a horse and wagon. It works adequately, but I've a hunch that a replacement is imminent in the next ten or twenty years. That owner is a hoot, too - the R-22 system was a marvel to them back then 'cuz of its lack of inclination to poison or explode :eek2:
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Wow! them there are some good words, you are pretty intelligent for being over yonder in that part of the world, you must have graduated elementary school, I bet you were the only graduate in your class. :grin2:
 
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Discussion starter · #14 ·
Mr Bill said:
Wow! them there are some good words, you are pretty intelligent for being over yonder in that part of the world, you must have graduated elementary school, I bet you were the only graduate in your class. :grin2:
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Heck, when I went to grade school, the notion of graduating from it was not a thing. Just started goin' to a different school the next year is all. We didn't get no graddy-a-shun 'till high school, and I made it outta that by bribin' the principal with three twelve packs of Natural Light and a couple of those gas station heat lamp burritos.

Can't find any visual evidence of a leak. High side pressure doesn't suggest a leak to me, but perhaps it ain't runnin' long enough to spew the lowdown. The way the two sides equalize seem point away from a bad leak. I think it's simply low on refrigerant due to a small leak. My goal is to nurse that system to outlive its very old owner while obviously following EPA regulations. She lives in a rural area with no other regulatory constraints.

It's odd that there's not an easily found summary going past the basics of gauge readings and the conditions they ended up representing.

I'll update when this gets figgrd out....just 'cause.
 
#15 ·
Well, actually there is. Problem is, this site does not allow us to get into the DIY end of things, so we are rather limited on what we can say in front of every homeowner out there. Looks like you're down to the most common 'trick' in the book, just add refrigerant and see what happens. Of course, as professionals we can't recommend that, there is a chance that could have detrimental effects. Either way, let us know what happens.


Freon Russell said:
Heck, when I went to grade school, the notion of graduating from it was not a thing. Just started goin' to a different school the next year is all. We didn't get no graddy-a-shun 'till high school, and I made it outta that by bribin' the principal with three twelve packs of Natural Light and a couple of those gas station heat lamp burritos.

Can't find any visual evidence of a leak. High side pressure doesn't suggest a leak to me, but perhaps it ain't runnin' long enough to spew the lowdown. The way the two sides equalize seem point away from a bad leak. I think it's simply low on refrigerant due to a small leak. My goal is to nurse that system to outlive its very old owner while obviously following EPA regulations. She lives in a rural area with no other regulatory constraints.

It's odd that there's not an easily found summary going past the basics of gauge readings and the conditions they ended up representing.

I'll update when this gets figgrd out....just 'cause.
Click to expand...
 
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#16 ·
Freon Russell said:
Heck, when I went to grade school, the notion of graduating from it was not a thing. Just started goin' to a different school the next year is all. We didn't get no graddy-a-shun 'till high school, and I made it outta that by bribin' the principal with three twelve packs of Natural Light and a couple of those gas station heat lamp burritos.

Can't find any visual evidence of a leak. High side pressure doesn't suggest a leak to me, but perhaps it ain't runnin' long enough to spew the lowdown. The way the two sides equalize seem point away from a bad leak. I think it's simply low on refrigerant due to a small leak. My goal is to nurse that system to outlive its very old owner while obviously following EPA regulations. She lives in a rural area with no other regulatory constraints.

It's odd that there's not an easily found summary going past the basics of gauge readings and the conditions they ended up representing.

I'll update when this gets figgrd out....just 'cause.
Click to expand...
Are you just checking pressures or are you taking line temps also? Does this have a TXV or fixed?
 
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Discussion starter · #17 ·
I'm not big on tricks, really. Gonna be very thorough in checking electricals, etc. and will absolutely calculate subcool, etc. Hack jobs ain't my thang. I have seen one situation somewhat like this in which the problem was a sketchy electrical connection at the blower, but that seems rather unlikely given the low side pressure consistency of the shutdowns 25psig and restarts 55psig.

While I ain't gots the gear or know-how of you fine people here, I'm a fanatic tech when it comes to being thorough and doing a good job. Example - I watched a large tire chain do a brake job they charge top dollar for while having tires rotated. It took less than ten minutes. Old pads out, new ones in, nothing else. It was a disgrace. I spend hours on that job, with all surfaces and threads cleaned, proper consumables used, old pads numbered, wear measured with calipers, notes taken, entered into spreadsheet. My goal is to always knock it outta the park.
 
Discussion starter · #18 ·
BNME8EZ said:
Are you just checking pressures or are you taking line temps also? Does this have a TXV or fixed?
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Just pressures so far, but I'm headed back out there (her permanent crib near one of my vacation homes) this weekend after recovering some of my gear from storage back home.

TXV. The coil was astonishingly clean, esp. for its age. Same for the squirrel cage. The Skuttle DB-25-20 has done an excellent job, and I got it less than the cost of a decent pizza.

Thanks again for your and everyone's input, sir.
 
#19 ·
BNME8EZ said:
Are you just checking pressures or are you taking line temps also? Does this have a TXV or fixed?
Click to expand...
Please remember we are in AOP and cannot delve into technical matters here.
 
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