Ac was operating upon arrival. After having the customer explain the noises they are hearing and listening myself. I was unable to hear anything at this time. Customer noted that the noise tends to happen in the morning time. I ran my diagnostics and made sure everything was assembled correctly and after these tests I was still unable to pin point exactly what could have caused the noise to happen. We will return on a later date to replace the filter drier for the correct model and I will try to have the return visit scheduled first thing in the morning so that I can hear the noise my self. For the time being I do not recommend running the heat pump in heating mode.