Is it a 160 or 180 degree thermostate?? More likely you have a 160 or faulty thermostate that stays open all the time. I have in my 95 GMC
1500 a 160 thermostate and it never goes over 170 degree. Before getting this thermostate I used to have a faulty one too. I am driving 25 miles every day to work through traffic. It takes me like
40-45 min to get there and by the time i was getting to work it bearlly warmed up the cabin(after40-45min).Now I get heat in the cabin like after 5 min of driving. When it idels it needs a little more time to heat up.