1991 Pro 60 Overheating

Last spring I had the impeller replaced after the overheating horn sounded. Throughout the year I experiended some heating issues. This spring the dealer replaced the sensor. Everything fine until this week when horn sounded again. Only happens when *****ing.

did they clean the poppet valve?
replace t-stat
replace housing?

As far as I know the only thing they did was to replace the impeller and sensor. Am taking it back this week and will mention these items.

Thanks

As far as I know the only thing they did was to replace the impeller and sensor. Am taking it back this week and will mention these items.

Thanks