Vent shuts down

The vent fan will only operate in low speed mode while the microwave is working. This is a new appliance purchased because sales told me it had a strong vent, but this weird problem of it shutting down is not acceptable. Samsung claims that ALL their microwaves’ fans shut down to low when operating microwave but that is not what other Samsung user manuals state. SMH9187 Pg. 20. "Vent operates in 1-4 levels of 5 speed." I want to exchange my new microwave for one that the vent works on at least medium. Am I the only person who uses the range cook top and needs the vent while I cook in the microwave? Can’t find anything on this problem and wonder who has a good working vent that is controllable?:confused: