Heat Pumps and Electric Heating - Carrier heat pump trumpet noise

Our newly installed Carrier Infinity heat pump makes a loud snorting noise, like an elephant call, or a tool box scraping on a cement floor, a short trumpet blast. This noise lasts a second or two and only occurs in cooler weather near and below the freezing mark. Otherwise, it works fine. For the entire winter season on the coast, whenever the temperatures dips to freezing or below, we have been wakened during the night by this loud trumpet burst noise just prior to the unit going into its defrosting cycle. The unit goes into auxiliary heat to help defrost the outside coils outside and we see the steam rising.

Several visits by the installer and several calls to Carrier have been made but despite adjustments to dip switches and whatever else (no new parts) the noise persists.

It appears from the previous post that this noise problem has been around at least since 2004 and the fix required replacing the reversing valve which Carrier appears reluctant to do without putting the consumer to a lot of trouble.

Has anyone else experienced this problem?
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Brent,

I am thinking it is the gas escaping from high to low in the rev. valve as it is supposed to, maybe the valve is a little slow so it is forced through a small orifice to begin with making that proverbial Trumpet noise, probably wont hurt but I am sure it is annoying, if it is that bad and they will not cover the replacement , get a few quotes to replace it.

Id say also the Reversing valve. Id lean on the company that put it in. Get them to change it.;)