Air Conditioning - Air Conditioner out of freon

My AC unit is not cooling. The serviceman came by said it was flat out of freon. He added some and then checked for leaks with something that made beeping sounds, but couldn't find a leak in the condenser coils or around the evaporator on top of the furnace in the garage. Since the freon was all out, he thought it was a large leak, and they would have to do a leak check by cutting into the line and adding pressurized nitrogen and watch it. That test could take up to a week.

He said I would have a bigger problem if the leak is the evaporator coils as the design had changed on those and I don't enough space above my furnace so I would have to replace my furnace if that was the case.

As it was going to cost $300 to charge with refrigerant, I wanted to get some feedback on this before I did anything further.

Help is appreciated.

I would get another opinion. For most markets, 300 seems high for just freon.

You post implies that the entire charge was lost and the leak should be easy to find. I agree, it should be easy to find but I am confused as to why it was not.
Lineset leaks do occur, but not very often, and usually as a result of someone driving nails through the wall. Most times the leak is in the evap coil. A bit more time should be concentrated in that area first.

I would just keep an eye on it for now. Put some white out or something simular to see if kids are removeing the service caps and huffing the freon.

$300 bucks for a gas and go is very high.

Any good tech should be able to find the leak pretty quick unless it's very small. In that case they would add die and it may cost in the neighborhood of $150 - $200 for this.

Was it operating good previous to this finding ?

Thank you. I am calling in a second tech that was recommended by a coworker. I'm not sure why the leak wasn't detected. It could be because it's in the evap coil (I hope not, as the I'm told the furnace will have to changed out!).

I'll see what the second opinion will be.

Thanks again.