HVAC Water Hammer-Spring Noise When Compressor Starts.

[HMHaggy]

When my Bryant HVAC system compressor starts I hear pipes knocking and a spring pulling/snapping noise. Later the inside fan starts. What is this water hammer noise? What is causing this? Could it be not charged properly? The spring noises it near the TXV. Sometimes it sounds like a hammer hit my furnace. My wife even notices this noise. Is this noise damaging to my HVAC system? Could this issue be caused by not using an inert gas to braze with when the system was installed?

[Freon]

Possibly the refrigerant lines have come loose from where they were attached. You might go to the air handler and put your hands on each line and have someone then call for AC. You should feel the vibration as the refrigerant starts flowing. In the beginning it's a combination of liquid and air but after a few minutes it should be only liquid. The initial vibration should stop in a minute or 2. If not and you can hear the flow you may be low on refrigerant. I am a believer in having a sight glass at the evaporator coil so you can always tell what's flowing to the coil.