Question about Reefer Temp

Are you running it on Continuous or Cycle Sentry? On Cycle Sentry, the unit can warm to about 5 degrees above the set temperature before turning back on. Have you done a manual defrost, especially after the trailer doors have been open?

 

On Continuous, the temperature usually stays within 1 degree of the setting (except during a defrost). A 7 degree difference is a lot, especially if you were to haul produce, so get it checked out. Maybe the display is not an accurate reflection of the real internal temperature since you mentioned a temperature recorder did not show the temperature fluctuation. You wouldn't want to pull into a receiver and have them think the reefer temp was too warm.

The other question would be the temperature of the product loaded. If it was warm, the reefer may not ever get cooled down to the set temperature, depending on the length of transit time. Do you have a problem maintaining a set temperature with an empty trailer? If so, then I would definitely have Thermo King take a look at the reefer unit.

 

Look at the seals on the doors and also the insulation under the floor. I've had blown tires shred the under floor insulation. Check the overall integrity of the trailer.

 

Knowing what you're hauling would be helpful and if you're running continuous or start/stop. Summer temps are here and produce loaded hot and on cycle would run up that high before starting, but produce should never be run on cycle. Dairy on the other hand, I might be a little concerned. I have a feeling running it on continuous will solve your slightly larger then normal temp swing if you are running continuous, it may be icing up too quickly meaning it needs to get looked at

 

The only time mine does this is when it's froze up. I have a carrier now but I have had to turn off and back on both a carrier and TK unit to get them to defrost properly. This has happened to me a couple times when loading out of the Rio Grande Valley when it's HOT and HUMID.

 

I would take the time to go through all of the settings on the unit and reduce the defrost times as much as it will allow and minimize the variances. It's always a good idea to check deep in the settings because I've seen some that I would think a 5 year old was seeing how much damage they could do. If it is set to defrost every hour it isn't going to be able to pull back down and maintain a good temp. Also....I'd suggest getting a laser thermometer to verify the actual temperature rather than just the unit readings.

 

Gusher, did you figure out ahat the problem was?
Mine does the same thing, lets say you set it at 65f, it would cool down to like 59-60 and will heat up to 70 and cycle starts over.....

 

Buy a laser temp gun and make sure that’s the actual temp, if it is, Unfortunately I would start at a tk dealer and have them put a computer on it to make sure it’s not programmed to have that much of a swing, like maybe if the original owner was hauling something not finiky, then I would start with sensors, providing the doors and walls have no large gaps.

is the high speed working? If not it might just be taking longer to come down to temp