Hello - Like I said, there is no converting to 208 volts. If you have 3 wires (white black and bare or green) the white and black are hot and the bare or green is common.
If you have 4 wires (red, black, white, green or bare) then the re and black are hot the white is common and the bare or green is ground.
If you look in the panel you can verify the (hot) colors going to the unit from the breaker, and the common color from the common bar. While your in the box go ahead and measure the voltage at the breaker - likely it will be less than you think. There are step down transformers available but you don't need one. Let me know if you need more info. Thanks
OK - the 2 black wires are hot, the white is common, and the ground well is ground. Your A/C compressor will work just fine on the line voltage you have ! Do all of your 110vac lights and appliances have a problem with 120vac ? Did you measure the voltage in the box ? What type of work do you do on these "medical imaging cameras" ? Take a voltage reading on one of them once and you'll see there's more than 208volts feeding them.
Please note also , IF the cameras you speak of are in a hospital setting and actually do have 208 vac feeding them, rest assured that the hospital has a series of filters and transformers and isolation devices and backup power and in some cases even make their own power. All of which come at a great cost, which is outside the reach of the average consumer.