I HAVE freezer that it is 3 years old it has started freezing up the coils.
Answer Hello Marvin. It sounds like you may have a defrost problem with the unit. Check and see if there is any frost build up on the evaporator coils in the freezer. If so, you will need to test the defrost heater and the defrost thermostat. They should read closed for continuity when cold. You can test this with a multi-meter TJMA-DMT3. I will include a link at the end to assist you how to use the multi-meter if needed. If both parts are good, you will need to replace the defrost timer. Once the problem is repaired, you will need to thaw out the ice on the coils before the unit will operate properly. http://forum.appliancepartspros.com/oven-repair-including-ranges-cooktops/4810-how-check-continuity-ohmmeter.html
Unit works when door is closed but when I open the door the freezer turns off and the control panel blinks so does the interior light.
Answer Hello Ted. You need to look for a bad connection on the unit. A bad wire or connection will cause the issue you are having with the unit.
This freezer belongs to a friend and asked me if I would check it. I checked the compressor and cap. Then both check fine with a meter. The control panel on the front looks fine. The freezer doesn't do anything, it just sits there. No alarm, no high temp light, & no door agar light. You can raise the temp, turn it off, & so on. My friend explained to me they had a power outage, & when the power come back on, the numbers on the LED were scrambled. She unplugged it and plugged it back in, & then it had a dash here and there but that was it. She tried it again & the numbers come back. That is how it is now but still nothing. I am thinking it is the control board. I took it out & inspected it & see nothing that looks burnt or damaged. I am thinking it is the control board, is there a way I can be sure.
Based on the information it does sound like the control board is bad and would need to be replaced. There really is not a test but if nothing is getting power then the control board would be the issue.