Need comments from the pros. My upper level heat pump air handler and coil are in the attic. It has a TXV added by the installer to boost the SEER to 12. This system is now over 6 years old. The installer installed an 11 SEER coil (among his several goofs) and the Trane rep instructed him to add the TXV. It has worked without technical problems. But do TXVs sometimes make noise? The noise varies, sometimes faint buzzing of changing frequency and other sounds. The noise of the blower is consistent and I do not think it is the blower.