heating question

[gary1998]

A previous owner fitted/mounted heater box on wood for some reason i don't know why (i think there's a gap that shouldn't be there) as i get cold air all the time seems to come in near rear of headlight drivers side if that makes sense .. now i have a 1y and it never really gets very hot heating is "pooh" gauge barely up to 1/4 ... now i'm thinking if i block fresh air scoop behind grill (if that's what the scoop is for) will that mean heater-box will get nice and toasty ie as no cold air rushing in and with fan on cab will get nice and toasty or will it over heat and kill heater/engine

[kevtherev]

The guage not reaching the middle quickly suggests the thermostat is not working or faulty