Defrost heater wont heat up

Question

I have the familiar issue with frost build up on the evaporator, which if unfrosted causes the fridge to stop cooling properly.The heater works fine once connected directly to 220V, and reads about 130 Ohms.The thermostat reading when closed is 0 Ohm.The defrost timer operates fine - when moved manually to defrost mode it stops the compressor/ fan of the fridge. After about 30 minutes it automatically advances to cooling mode.At defrost cycle I disconnected the heater to test the voltage across its relevant terminals and the reading is 206 Volts. This seems odd to me, as I expected the 220V reading. When the heater is connected the reading across it during the defrost cycle is 0 Volts.I would appreciate any help.\please feel free to contact me at [e-mail]