Hi Michel, thanks for your post.
Be careful, this smell could be coming from electrical wires that are melting because the AC is pulling too much current or neutral wires are not properly installed.
Have you identified that the smell comes from the AC or can you sniff around your breaker panel to see if perhaps the smell is coming from there.
Please address your breaker box immediately as this is a common smell when a large appliance is turned on and wires are melting.
If you are certain it’s not coming from an electrical source, you could also check your condensation pan on you AC unit.
Best of luck, take care!