Help - Reefer Won’t Quite Reach Set Point

Hey Guys and Gals,

I’m having an issue with my reefer trailer and was hoping y’all might be able to point me in the right direction.

The past couple of weeks I’ve had a couple loads where the BOL said to set the temp to 34, and my trailer constantly stays right around 36. It occasionally touches 34-35, but for the most part it stays at 36. The part that is troubling me is that I’ve also had some -10 frozen loads in between the 34 degree loads, and on those loads the reefer was able to maintain -10 in the Phoenix heat no problem. So I don’t have the slightest clue why it isn’t maintaining 34 degrees.

The unit is a 2013 Thermo King SB-330 on a 2013 53’ Great Dane trailer. I just replaced my belts as one was cracking, but this issue was occurring both before and after the belt replacement. The computer isn’t throwing any codes either.

Does anyone have any ideas why this might be happening?

Thank you all!!

 

Most likely it's the heat of the load. Not an issue with the reefer.

 

Do you have it set in cycle or continuous? I’ve heard some units are programmed when they are set that close to 32 to kind of “buffer” the temperature so it’s not blasting freezing air over something delicate like leafy greens or berries when it kicks on. @Wasted Thyme is probably right tho it very well could be the core temp of the product.

 

Both loads have been continuous. Prior to noticing the issue, I had a 34 degree cycle load that reached the set point no problem.

Additionally, I saw somewhere on the forum about checking for gunked up lines. I just massaged the line underneath the unit that released the defrost water and a big chunk of something shot out followed by a bunch of water. Not sure if this could’ve been causing my issue, but will continue to monitor the situation.

Thank you both for the timely responses!!

 

What's the product?

 

The first load I noticed it on was Yogurt. The current load is Almond Milk.

 

If you're running it in the dock while loading do a manual defrost. The condenser partially freezes it will hurt. What's the RA? If you're putting 34 degree air in and the RA is 36-38 the product is warm.

 

What was the product you were hauling at 34?

 

Sorry I missed what the product was. I would get it checked out. Both yogurt and milk are always pre cooled before loading. There is a temperature sensor in the nose of the trailer, I have had one that was started to go bad before.

 

The unit goes into modulation mode on continuous when it nears setpoint.As was stated earlier,its to maintain setpoint without freezing the coil therefore it shouldn't need to be defrosted all the time and lose all moisture in the box.You might have a problem with that,but if the drain hoses were plugged that is most likely the cause.