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Started By
Message
A/C short cycling *Update in OP
Posted on 8/21/15 at 9:04 pm
Posted on 8/21/15 at 9:04 pm
I just moved into my house last week and tonight I am noticing that the A/C is short cycling really bad.
I can hear the click of the thermostat kicking on every few minutes. It is set to 74.
At the moment Im not sure exactly what size the unit is.
Any ideas?
UPDATE:
I bought a Lux brand touch screen programmable thermostat. It was the only unit at Lowes that did not have a 1* swing.
I installed it yesterday afternoon and messed with the damn thing all evening, making little progress.
This morning I changed it to manual mode from programmable since I didnt take into account the factory programmed settings and woke up sweating at 6am in 78 degrees.
I have messed with the swing settings ALL day and I think I have finally figured it out.
Set at 74 degrees with a 1.25* swing =
8:31 - On - 75*
8:50 - Off - 72*
9:06 - On - 75*
9:18 - Off - 72*
That puts me at damn near 2 cycles per hour
I will use that as my guide and set it at 74 while home, 73 at night and 75 while away. If 73 and 75 operate like the 74 has tonight, I should be in good shape.
I can hear the click of the thermostat kicking on every few minutes. It is set to 74.
At the moment Im not sure exactly what size the unit is.
Any ideas?
UPDATE:
I bought a Lux brand touch screen programmable thermostat. It was the only unit at Lowes that did not have a 1* swing.
I installed it yesterday afternoon and messed with the damn thing all evening, making little progress.
This morning I changed it to manual mode from programmable since I didnt take into account the factory programmed settings and woke up sweating at 6am in 78 degrees.
I have messed with the swing settings ALL day and I think I have finally figured it out.
Set at 74 degrees with a 1.25* swing =
8:31 - On - 75*
8:50 - Off - 72*
9:06 - On - 75*
9:18 - Off - 72*
That puts me at damn near 2 cycles per hour
I will use that as my guide and set it at 74 while home, 73 at night and 75 while away. If 73 and 75 operate like the 74 has tonight, I should be in good shape.
This post was edited on 8/23/15 at 9:30 pm
5
Posted on 8/21/15 at 9:09 pm to Polar Pop
What are the on and off intervals?
Electronic thermostats often let you set the maximum cycles per hour.
ETA: The thermostat "swing" could also have an effect. If it's very tight, it could cycle more. This can often be set, but my fancy Honeywell TH8000 has it fixed at 1 degree.
Electronic thermostats often let you set the maximum cycles per hour.
ETA: The thermostat "swing" could also have an effect. If it's very tight, it could cycle more. This can often be set, but my fancy Honeywell TH8000 has it fixed at 1 degree.
This post was edited on 8/21/15 at 9:12 pm
Posted on 8/21/15 at 9:31 pm to Spock's Eyebrow
Thanks for the information Lennox digital unit that surprisingly doesnt have a settings menu.
I changed the Fan Mode to "On" instead of "Auto". Hope that helps.
I plan on getting a Nest in the future but would like to get this figured out in case there is something that needs to be fixed on the unit.
Posted on 8/21/15 at 9:34 pm to Polar Pop
I am assuming this is new construction?
If so, who sized the unit?
The unit will not dehumidify unless it can run for longer periods of time.
If so, who sized the unit?
The unit will not dehumidify unless it can run for longer periods of time.
Posted on 8/21/15 at 9:37 pm to Polar Pop
quote:
I changed the Fan Mode to "On" instead of "Auto". Hope that helps.
this will just make the fan stay on all of the time instead of shutting off when the house is cool enough...
check to see if there are a lot of vents right around the thermostat making it that area cool off a lot faster than the rest of the house when the unit kicks on...mine is mounted in such a place and I have to either close vents in some of the nearby bedrooms or close the doors to force air to the other end of the house to stop the short cycling...
the right way to fix this would be to install adjustable dampers in the ductwork, but I am too cheap for that...
Posted on 8/21/15 at 9:38 pm to Polar Pop
Could be too much head pressure.
Maybe low freon icing up
The inside unit. Thermal switch on the compressor shutting it down. Or a really dirty filters.
But prob l low ( or high) freon.
Maybe low freon icing up
The inside unit. Thermal switch on the compressor shutting it down. Or a really dirty filters.
But prob l low ( or high) freon.
Posted on 8/21/15 at 9:39 pm to Polar Pop
quote:
I changed the Fan Mode to "On" instead of "Auto". Hope that helps.
It won't help your electricity bill.
Plus it will almost certainly draw in some air from holes in the building envelope, from the attic and outdoors. What are the intervals that make up the cycle? That is, how long is it on, and how long is it off?
Posted on 8/21/15 at 9:47 pm to AndyCBR
quote:
I am assuming this is new construction? If so, who sized the unit?
2006, I just bough the house though.
Not exactly sure what size unit, I will have to check tomorrow.
Thermostat is in hallway with 1 bathroom in the middle and 2 bedrooms on the ends. No vents in hallway.
Filter is brand new as of 2 days ago.
I might just have someone come check it out next week.
It is out of control, like 10 minutes on, 2 minutes off.
Posted on 8/21/15 at 9:47 pm to Polar Pop
quote:
Lennox digital unit that surprisingly doesnt have a settings menu.
Before you concede that as fact, google the t stat serial number for a book to that model. It may be as simple as holding two certain buttons for5 seconds or something to get you in a menu screen.
Posted on 8/21/15 at 9:53 pm to Polar Pop
well, we know it is not heating up enough in 2 minutes to warrant the unit coming back on...
does it seem to be keeping the place cool?....
does it seem to be keeping the place cool?....
Posted on 8/21/15 at 10:00 pm to Spankum
The entire house is cooling easily besides the 2 bedrooms at the end of the hall where the thermostat is.
Im afraid I have a larger issue at hand
Im afraid I have a larger issue at hand
Posted on 8/21/15 at 10:01 pm to Polar Pop
quote:
It is out of control, like 10 minutes on, 2 minutes off.
Yeah, it it were crack, it would be wack.
If that 2 minutes off is for real, it's also potentially bad for the compressor. The thermostat ought to impose a 5 minute delay.
When it's really hot, mine will sometimes cycle with that minimum 5 minute off-time, but the run times will be a lot longer than 10 minutes, more like 45 minutes. I blame that on my Honeywell's unadjustable 1 degree swing and the 130 degree attic above me.
Posted on 8/21/15 at 10:13 pm to Spock's Eyebrow
Most recent cycle
On from 10:02 to 10:08
Off from 10:08 to 10:13
On from 10:02 to 10:08
Off from 10:08 to 10:13
Posted on 8/21/15 at 10:21 pm to Spock's Eyebrow
quote:
130 degree attic above me
I made one of these to insulate my attic steps which is located above my thermostat. Really helped hall temps which has no A/C duct. The hall was several degrees warmer than the rest of the house. Now the temps are same in hall and adjoining rooms.
Posted on 8/21/15 at 10:22 pm to Polar Pop
Is it a fancy system with dehumidification or no?
Posted on 8/21/15 at 10:30 pm to BigEdLSU
I dont have a clue. I doubt it though. Im pretty sure this was built as a spec home in 2006.
Posted on 8/21/15 at 10:33 pm to Polar Pop
Lots of thermostats these days have reset buttons on the back. Not saying it's likely, but I'd reset it and change the batteries... Sometimes they go nuts. Seems like if it was high or low pressure switches cutting the unit off, it wouldn't make it 6-8 minutes.
I'd try the simple stuff and if it doesn't work call a pro.
I'd try the simple stuff and if it doesn't work call a pro.
Posted on 8/21/15 at 10:38 pm to Polar Pop
It sounds like the air is blowing directly on the t-stat. You could try to make a temporary shroud to keep the air off of it.
You could also get some cable and make joints at the stat and put the stat somewhere else.
If it was a mechanical problem, the stat would not be dropping in and out. I have had bad capacitors and low refrigerant this summer and the unit just kept trying to run, and did not cycle.
You could also get some cable and make joints at the stat and put the stat somewhere else.
If it was a mechanical problem, the stat would not be dropping in and out. I have had bad capacitors and low refrigerant this summer and the unit just kept trying to run, and did not cycle.
Posted on 8/21/15 at 10:43 pm to Polar Pop
I had the same exact problem a few months back when we first moved in our house. 'Problem' was a honeywell thermostat that was designed to keep the house at an almost constant temp. It did not have a temp differential at all-replaced it with a cheap programmable one from lowes that i am able to set to a 2 degree differential. Works like a charm now.
Posted on 8/21/15 at 11:19 pm to Polar Pop
quote:
Most recent cycle
On from 10:02 to 10:08
Off from 10:08 to 10:13
The 5 minute off time is good per my earlier post, but that's 5 cycles per hour (CPH), which is too much IMO. Look up your thermostat and see if it's possible to lower it. My Honeywell defaults to 3 CPH, and it never does like yours even though it's got that unadjustable "constant comfort" 1 degree swing.
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