Thermo King V300max

Hi, I recently bought a 14 foot box mits fe185 with a thermo king v300max in it. It worked great for awhile and then suddenly it would sound like it was in defrost upon first starting the unit in the morning. When it would finally come on it would start and stop start and stop continuously. Sometimes it comes on fine and works. Sometimes if i hit the defrost button when it starts out sounding like it is defrosting it will come on and function once the cycle is complete. Sometimes it has been working and will start doing it after i have to shut the truck down somewhere. THermo techs told me it is low on *****. Had it checked by two different sources and has been fine both times. Could it be a defrost sensor or temp sensor? I notice when it does this it will remain at 45 degrees most of the time. Sometimes it will go to 55 and stay there, but mostly 45. It will even feel colder than that in back sometimes when it is doing the start stop. Other times it doesn't act like it is cooling enough. Any ideas? Has anyone dealt with this before? One place supposedly fixed a loose wire at the compressor but it worked for only a day. Could have been total **** luck and it was just an on day.....it does that sometimes. Almost seems like it is worse on wet days, but i am not certain that this isn't coincidental as it is wet in Vermont a lot.....

Intermittent fault on the evaporator fan? condensor fan,if you defrost it manually say every two hours does it work ok you may have an issue with the defrost timer not defrosting enough.

Hi, sorry i didn't respond. Been having an issue getting on the board again. I realized that i somehow in my onsetting blindness had entered an extra i in my user name when i set it up and never noticed it lol.

I tried to manually defrost. Doesn't seem to affect it. Lately it started working again and has been working for 5-6 days without issue. I know it will not last however. It has done this before. It randomly started after we shut the truck down at a stop. When we turned it back on, it came on as it should and has worked since. I am still leaning toward a defrost issue, because when it is operating it does seem to frost up quite a bit very quickly. I am not sure if that is an issue being that it is a freezer unit even tho i am operating it at higher temps (36 degrees) My larger units don't look like this so i have never noticed if they ice up that way or not.

Get the filter drier changed you may have moisture in the system,I like to change them every twelve months,you will need a technician to change the drier,and see how that goes best of luck.