Dancing Bear
Well-known member
Greetings everyone, and thank you in advance for taking a look at this.
Long story short, I was working from home yesterday and I noticed that during the hot afternoon (~2pm), my outside condenser unit was short-cycling. It would start, run for about 5 seconds, then shut down. This happened roughly 3-4 times before it successfully started, and ran for about five minutes before shutting down and repeating the process. During this time, the temp outside was ~90 in Clearwater with a high heat index, thermostat was set at 70 inside (girlfriend works overnights and likes it cold to help her sleep comfortably).
The system had no issue maintaining the temp in the house, even at the hottest part of the day, but the short-cycling concerns me that it will reduce the lifespan of the unit. It's a Carrier system that was installed in 2016. Sadly I didn't have a ton of time yesterday, but I did do some quick searching online and tried a few small things:
- Changed air filter (wasn't plugged badly, but due to be changed)
- Removed condenser fan and vacuumed inside of condenser pan and gently rinsed condenser from inside-out.
- Rebooted thermostat (Google Nest) and checked for loose wiring. Wiring clean, secure, no signs of issues at the thermostat.
- Checked evaporator coil and AC lines for signs of freezing. Evap looked nice and clean with very minimal dust (I cleaned it in 2022) and lines were wet with condensate but not frozen at all.
- Checked temperature delta between air supply and return. 18 degree temperature difference, 56 degree supply air temp so no issues detected.
Sadly, none of these things helped. The unit continued to short-cycle on and off BUT oddly enough, at around 6pm while I was finishing work, the unit started on the first try and then continued to run. I was cooking dinner and was able to listen to the unit for the remainder of the evening, and no short-cycling was observed. It would shut down as normal, then start and run on the first try each time. It would run for roughly 1 hour 15 minutes and then shut down as normal.
Unit worked beautifully the rest of the night, I woke up to a comfortably cool house around 10:00am. At around 11:30am, I heard the unit start short-cycling again. It appears that the issue is occurring at the hottest parts of the day.
I did some additional research today and found that the Nest thermostats are prone to have short-cycling issues. Admittedly, I'm no expert but the Nest support forum said a factory reset might resolve the issue. I'm no expert in AC at all, but I do have a meter and planned on checking the capacitor and contactor to see if they're out of spec.
Does anybody have any ideas what it could be, or any additional troubleshooting steps I could take? I don't want to fire the parts cannon at it, but I'm thinking being almost 8 years old, it may be time for a new contactor/capacitor anyway, and they *may* be causing the issue?
As always, thanks for your help
Long story short, I was working from home yesterday and I noticed that during the hot afternoon (~2pm), my outside condenser unit was short-cycling. It would start, run for about 5 seconds, then shut down. This happened roughly 3-4 times before it successfully started, and ran for about five minutes before shutting down and repeating the process. During this time, the temp outside was ~90 in Clearwater with a high heat index, thermostat was set at 70 inside (girlfriend works overnights and likes it cold to help her sleep comfortably).
The system had no issue maintaining the temp in the house, even at the hottest part of the day, but the short-cycling concerns me that it will reduce the lifespan of the unit. It's a Carrier system that was installed in 2016. Sadly I didn't have a ton of time yesterday, but I did do some quick searching online and tried a few small things:
- Changed air filter (wasn't plugged badly, but due to be changed)
- Removed condenser fan and vacuumed inside of condenser pan and gently rinsed condenser from inside-out.
- Rebooted thermostat (Google Nest) and checked for loose wiring. Wiring clean, secure, no signs of issues at the thermostat.
- Checked evaporator coil and AC lines for signs of freezing. Evap looked nice and clean with very minimal dust (I cleaned it in 2022) and lines were wet with condensate but not frozen at all.
- Checked temperature delta between air supply and return. 18 degree temperature difference, 56 degree supply air temp so no issues detected.
Sadly, none of these things helped. The unit continued to short-cycle on and off BUT oddly enough, at around 6pm while I was finishing work, the unit started on the first try and then continued to run. I was cooking dinner and was able to listen to the unit for the remainder of the evening, and no short-cycling was observed. It would shut down as normal, then start and run on the first try each time. It would run for roughly 1 hour 15 minutes and then shut down as normal.
Unit worked beautifully the rest of the night, I woke up to a comfortably cool house around 10:00am. At around 11:30am, I heard the unit start short-cycling again. It appears that the issue is occurring at the hottest parts of the day.
I did some additional research today and found that the Nest thermostats are prone to have short-cycling issues. Admittedly, I'm no expert but the Nest support forum said a factory reset might resolve the issue. I'm no expert in AC at all, but I do have a meter and planned on checking the capacitor and contactor to see if they're out of spec.
Does anybody have any ideas what it could be, or any additional troubleshooting steps I could take? I don't want to fire the parts cannon at it, but I'm thinking being almost 8 years old, it may be time for a new contactor/capacitor anyway, and they *may* be causing the issue?
As always, thanks for your help