Defrost cycle clicking sound.

by Paul
(Phoenix Arizona, USA)

Carrier Model 38YCA

Both my outdoor units make a clicking sound at about one click per second when in defrost mode. I have identified the source as being the reversing valve energizing for a moment.

The outdoor fan does not stop, and the coils fail to defrost.

The problem is a function of the little circuit card which features two CD4541 timers and a CD4066 quad transmission gate. If anyone has a schematic of this card I will be able to troubleshoot it down to some itty-bitty 50 cent part.

Note: I would never recommend the use of CD4000 logic in a potentially damp location.

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