Acne mechanica develops if you sweat more and the sweat is accompanied by some pressure and/or rubbing.
Sweat is produced by sweat glands and acne forms on the hair follicles. There is no direct connection between the two. Excessive sweating will not reduce the acne. It may increase acne.
Despite the belief that acne gets cleared by sunshine, there is no scientific evidence to this. Excess sun can damage your skin rather than treating acne.