Performed residential warranty. Homeowner states that there is a knocking noise in the master bedroom wall. We were recently out here to run a new line set to master bedroom unit because of the knocking noise. Noise had stopped for a bit but has came back intermittently. Ran systems on that side of the house on and off a couple times. I could hear noise that homeowners are mentioning. However, lineset to the other unit that is on this side of home is running up inside the wall exactly where they are mentioning that they hear the noise. Lineset is running up the same spot where the old lineset is running. More than likely the noise is now coming from the other unit as that is the only possibility at this time. Spoke to homeowner about what is going on. Due to this being an intermittent issue, it would have been hard to identify this issue because it was not happening when tech was last out here to check the system. Homeowner understands what is going on. He is going to wait and see if i