new ball python owner

[mues155]

is 75 degrees too low for the cool side of tank at night?

Yes 75 is dangerously close to being harmful.

Temperatures should be as followed...

80-82 cool side
86-87 warm side
92-93 hot spot

Anything below 75 is unhealthy.
If these temps continue the snake can have problems such as failure to eat, and can also lead to fatal respiratory infections.
Temps are VERY important to keep accurate for a reptile.