I don't think you understand the concept how the pump works.
The pulley on the aircon pump freely spins with the belt. The Aircon pump still isn't working until the clutch engages within the pump and then the centre of the pulley begins to spin with the pulley. It engages and disengages every minute or so. Its clearly visible if you look at the side of the pulley with the engine on and the aircon on.
Driving your car without any aircon gas is fine. No harm done. Did you know If the pressure within the aircon system drops to a certain PSi due to lack of refridgerant the aircon pump electronically shuts itself off anyway and wont work till the correct amout of refridgerant is put back in, it stops the system running dry which would cause problems to the aircon system.
So once fitted you can drive your car to a garage to get it regas'd with no problems whatsoever.
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