Both real good responses.
You might want to disconnect the low pressure switch to keep the compressor from coming on. Jim's right about letting the system go killing the cars value. Anyone asking me about purchase info on a 300E with no A/C gets a $3000 subtraction on value and a strong no-buy suggestion based upon the concept that anyone that would own a MB and let the A/C go has undoubtably let most everything else go.
As far as I am concerned A/C is only second to brakes as a necessary part of a MB.
Bosch Master, ASE Master, L1
33 years MB technician