No — an air-conditioner and a geyser should each sit on their own dedicated circuit, never a shared one. Both are among the heaviest loads in a home: a 1.5-ton AC draws roughly 1.5–1.8 kW and a geyser 2–3 kW, so together they can pull well over 20 A.
Put them on one circuit and you invite trouble. The shared cable and MCB can be overloaded whenever both run at once, causing nuisance tripping at best and, at worst, an overheated cable — a genuine fire risk. Sharing also causes a noticeable voltage drop, so the AC or geyser underperforms, and it makes fault-finding harder because one tripped breaker kills two appliances.
The correct approach is a separate circuit for each high-load appliance, wired in a size that matches its current (commonly 4 sq mm copper for a 1.5-ton AC or a geyser) and protected by its own correctly-rated MCB. Lighting and general sockets stay on their own circuits. This keeps every appliance safe, avoids nuisance trips, and makes the distribution board easy to understand. If your home currently runs an AC and geyser off one line, ask a licensed electrician to split them.