carrier heat pump gear noise on defrost


Old 02-27-06, 09:08 AM
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Join Date: Feb 2006
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Question carrier heat pump gear noise on defrost

re: noise (gear grinding?) when carrier 38YXA030 goes into (or comes out of?) defrost cycle


after countless calls to carrier complaing about noise we learned that there is a switch on the outdoor unit that has some sort of control over the defrost cycle. Can someone explain what this does, and if there's a risk of causing a freeze-up?

Thanks in advance,

Alan Abrams
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Old 02-27-06, 11:18 AM
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Join Date: Jul 2002
Location: USA
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What you are probably hearing is the reversing valve, which reverses the flow of coolant to enable defrost. Defrost is a noisy (and sometimes steamy) process, you aren't the first to think something is wrong with it.

It's particularlly noisy coming out of defrost, less so going into defrost.
Old 02-27-06, 02:02 PM
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carrier defrost noise / dipswitch #3

thanks Pendragon. we are aware of the noise that is characteristic of defrost. however, it seems like it has been a bigger than average issue with the new carriers; apparently they redesigned their pump recently to address the noise issue.

Now they tell us--if noise is a problem-- to flip "dipswitch number 3" to the reverse position. But I'm having trouble understanding what that is supposed to do.



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