Will you blow the compressor if you start the engine with the ac on?

Will you blow the compressor if you start the engine with the ac on?
by compressor i assume you mean the air conditioning compressor. the simple answer is NO.

the compressor on all vehicles has a clutch which is activated by a solenoid that draws it in. that solenoid does not receive power until the engine and computer have run long enough to stabilize operations...generally 3-5 seconds. now on older vehicles (1950-1979) i am not 100% on their operations. in any case they won't operate until the voltage regulator stabilizes the power. it is not a mechanical engagement. therefore, again, no it will absolutely not blow your compressor.

even if it some how were to be stuck engaged and you started your engine unless there is a malfunction in the system it would still be just fine. it is a sealed system containing its own oil. failure by start-up is not possible.