The Eberspacher Easy Start T timer is NOT compatible directly with the B1LC air heater. It can be used as a timer, but you would also require temperature controller to allow room temp control. Is your heater the very early B1LC ? Or the later generation B1LC Compact?
If you can provide us with the exact type number ( read from the heater dataplate afixed to the heater casing) we could perhaps recommend an alternative controller for you