I have a 5 ton rheem heat pump. I came onto the job over the summer. The unit had had a leak and another contractor just filled it up and over charged the system. I came in, recovered the refrigerant, fixed the leak, evacuated system to 400 microns and properly charged unit. Unit has been working fine until now. The unit heats fine, but makes some horrible clicking/pulsating noises outside on the liquid line when the unit shuts down. It only does it on shut down. Any ideas? The only thing I can think of would be the TXV in the condenser.