# An airconditioner question

**URL:** <https://boards.straightdope.com/t/an-airconditioner-question/720539>\
**Category:** Factual Questions\
**Created:** [May 21, 2015, 7:15pm UTC](https://boards.straightdope.com/t/an-airconditioner-question/720539 "2015-05-21T19:15:15Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\
**Post date:** [May 21, 2015, 7:15pm UTC](https://boards.straightdope.com/t/an-airconditioner-question/720539/1 "2015-05-21T19:15:15Z")

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The new A/C quit working Tuesday. Not even the fan would run. Wednesday the installers replaced a 3 Ampere fuse and all was well.  
The is much more electronics in this A/C than the old one.  
What are the electronics doing?  
What was fused at three Amps that would stop the fan from running?

Thanks.

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**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\
**Post date:** [May 21, 2015, 7:42pm UTC](https://boards.straightdope.com/t/an-airconditioner-question/720539/2 "2015-05-21T19:42:57Z")

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There’s a “controller.”  
It does all the switching, sequencing the fan and compressor for maximum efficiency.  
The heat pump I installed a few years ago gets an extra SEER point by having a variable-speed blower - the blower stays on for a while after the compressor has stopped to extract that last bit of cooling or heating from the coils.

So, if the controller board goes, nothing works.

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**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\
**Post date:** [May 21, 2015, 7:58pm UTC](https://boards.straightdope.com/t/an-airconditioner-question/720539/3 "2015-05-21T19:58:20Z")

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> [@beowulff](#):
>
> So, if the controller board goes, nothing works.

Thanks, beowulff, and good luck with the dragon! 🙂