Sorry for the long post, but i needed to explain the situation in detail.

In mid June i got a new carrier 2 ton 13 seer unit. Base model, but all that was required for my 800 sqft second floor. The unit worked great for 3 weeks, then one night i heard a boom when the unit came on. it is located right outisde my full size downstairs bathroom. After that incident, everytime the unit came on i could hear it from start to stop. This is while i sat in my living area 60 feet away. Within the bathroom, the noise was unbearable. it was the compressor amplified in my bathroom. Also, most of my house hummed when the unit was on whenever you were 3 feet or closer to the wall.

The company eventually came out and placed vibration pads under the unit which was on a slab sitting on bricks so it didn't make contact to the ground. There was also space underneath the pad. This removed the humming through the house, but the noise in the bathroom remained although it was reduced in amps. they also loosened the compressor a little. I was told all readings were normal including amp draw.

The humming in the bathroom continued and worsened at night when the unit ran for longer periods of time. During the day the upstairs unit isn't on much so when on the hum is light. Same when it is first started at night. I realized the loudest sound is coming behind shower tile, the back wall which is adjacent to the outside wall. i can also feel vibration when hand is placed on tile since i have located the area where this and noise is strongest. It is approximately 20 inches high where it enters house.

My questions are what is causing the vibration in the shower wall, what was the loud boom, could a wall fastener come loose and if so, could that have been caused by the installers(see below) or just crap luck, is something wrong with the compressor. Cooling is still the same.

When they installed the condensor, they had it on the orginal slab which was wobbly and cracked. they replaced it the followind day by lifting it without disconnecting the copper. I wasn't there, but they had to remove slab, level out and then replace new one so is it possible they jarred ithe copper in the wall loose and the pressure of the compressor turning on popped it. There is some play in the small copper pipe and there is also some significant vibration, like a pulse. Just the other day the control pad area started make noises.

What are my options and what steps do you recommend taking in getting remedy since brand new ac units were not meant to be heard inside. The company seems sincere and has made good on many things.

Thank you.......i had no where else to go....