1. if left side is hot, right side is cold, notwithstanding
where the sun is shining in.
2. if ur air-con duct is eyeball-style, try turning it the other
way.
3. if ur air-con duct as an additional switch next to it, it is the
on-off switch.
4. for SMRTB dennis lance's, try adjusting the small rotating knob
in the centre. ur air-con might be off.