This is my first post on this forum but I think i've read every post in the refrigeration and ice making forum and let me just say there is a lot of knowledge here and this forum has basically made things much easier for me at work. I'm work part time for a refrigeration company and am in school at community college for commercial refrigeration and hvac.
I have serviced the following machine 3x in the past 2 weeks, not exactly sure what is happening. It is a Manitowoc QF0800A. It is an air cooled model. The first customer call was for "no ice". I took the front cover off and the led for "Discharge Temp" was blinking. The condenser was slightly dirty, I blew it out with nitro and cleaned with coil cleaner, I cleaned it really well. I thought I was done and got a call back "no ice machine shut down". I went back and the discharge temp light was on again. I got the manual, I checked the operation of the discharge thermister--it was mounted correctly on the discharge line and was reading right (i checked it with my own thermister insulated and clamped to discharge line at same location). I ohmed the ice machine thermister across a range of temps and the thermister was dead nuts on. Superheat is about 18 degrees, subcooling about 4 degrees--404a. Suction pressure is 5 pounds, head pressure ranges, fan cuts in at 245 and cuts out at about 210. I've read other posts on this forum and some people have jumped out the thermister with a resister of a certain value to trick the board, i'm considering that. But I wonder why it worked ok for so long and then gets this fault. I'm thinking of replacing the fan cycling control because I'm wondering if it isn't just maybe failing once in a while and tripping that thermister. Although I ran the machine for about 1 hour and temps were getting about 200 degrees on discharge line (thermister will stop operation at 245 for a set period of time also cuts out on low temp for a set period of time, but low temp hasn't been an issue). The area the machine is in is conditioned and stays about the same temp year around. Maybe I should jump out the fan cycling control what do you guys think Thanks