I'm not sure what you mean. How would a light raise ambient temps in a snake rack? You might get some slight result from the tub or two it is focused on but overall it's not going to do much in a multi-tub rack I wouldn't think. Keeping the room ambients at the right range either through an auxillary room heater or just keeping that room warm seems a much better, more stable option.
has anyone ever attatched a clamp lamp with a infared light bulb to your rack to raise the cool side temp rather than gotten a space heater?
I don't think this would work well. I think you would just create a hot spot in one or maybe 2 tubs and the rest of the rack wouldn't be affected.
Get a small oil filled space heater ($40 Walmart) and just heat the whole room (or the area around the rack at least)...much cheaper and safer in the long run.