I have a coldzone walking freezer and my evaporator has been freezing over!! When I go too the defrost timer and turn a head so the defrost will kick on it doesn't work? I have one right next to it and when I turn too defrost I put my amp meter on line 3 and it will read approx> 7 amps so I know that one is working. But the one for freezer A just won't energize. The defrost timer is about a year and a half old! Any body have any information for me would really appreciate it. Thanks Dan