Mine does same thing I set it at 70 it heats up to like 75 before it shuts off. Lets truck cool off pretty good before itmcomes back on too. Has done this since brand new
when you put any hvac system (reefer,apu,home hvac,car) on auto and set the desired temp. it will always turn on about 4 degrees below if its heat and shut off around 4-5 degrees above what ever the set point is. if its a/c the opposite it will turn on 4-5 degrees above and not shut off til its 4-5 degrees below set point. my apu does same thing. keeps these systems from turning on and off constantly
Don't think of the temp setting as an exact temperature. Think of it as a reference. Start at a low temp, say 60 and see where that gets you. Just adjust it to the setting that is comfortable. My bunk heater is off by 7 degrees.
Aren't those heaters supposed to run a bit after the flame goes out to cool it off? That might be enough to run it up a few degrees once the flame turns off.
what hegemeister said. they don't always work to the exact temp setting. try 66 degrees and see what happens. as the weather gets colder, you'll be up to 70. as 66 won't be warm enough in the lower temps. course, anything under 20 degrees and you risk not getting the truck started in the morning.
the flame dies down and the fan slows down. doesn't take long for cold air to be blown but the fan will still run for a couple of minutes after. at a slower speed. that continually gets slower and slower till it stops. unless of course, you turn the ignition key on. then it's full interrupt and braking. generally a good idea to turn heater off a few minutes before turning ignition on. ((( IN THE FL'S, ANYWAYS)))