Rear heat not working

Remember the rear heat unit function only when the front panel knob is place on the foot selector And the cold/ heat knob on heat. I had that the same problem on my 97. I hope it helps resolve your issue. Given that your rear unit is working fine.

I have a 95 e-150 Econoline with the same problem can somebody help me with that

Again, check your settings and make sure they are where they are supposed to be. ( front panel knob is place on the foot selector And the cold/ heat knob on heat.) if everything else fails, check your heater coil or door actuator switch, it may be close. Close is for cold open for heat.