Hvac compressor doesn’t come on when outside temp gets below mid 40s

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Chasesc61

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Joined Mar 20, 2023

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Discussion starter · #1 · Mar 20, 2023

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Unit is about 20 years old and has just started having this problem. When the outside temp drops below mid 40s the outside fan comes on but the compressor doesn’t. The run capacitor has been changed a few days ago but the start capacitor hasn’t yet neither has the relay. The contractors were changed about a year ago. I’m thinking that it’s going to be the start capacitor or the relay. When the outside temp gets high enough, the compressor starts up normally and the temp at the register gets to 90F before it shuts off.
Anyone with thoughts? Thanks in advance.

 

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rider77

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Joined Jun 30, 2014

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14,097 Posts

#2 · Mar 20, 2023

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Does your contractor have any suggestions on how to fix the issue?
Just to note, in case you missed the bright red banner at the top of the page, we can’t offer DIY advice here.

 

BNME8EZ

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Joined Aug 19, 2009

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25,203 Posts

#3 · Mar 20, 2023

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Did the tech that changed the cap do it above or below 45ish. Did he test anything or just change a part? Is this system all electric or does it have gas back up? If it has back up is there a lock out setting?

Seems like there was not a lot of diagnostics done. Yet at the same time it can be hard to simulate a problem when it has to do with outside temperature.