Refer not cooling right

Maybe your unit is not auto-defrosting like it should. Have you ever noticed it in defrost mode?

Try manual defrost a few times, 30 minutes apart. (Without opening doors)

 

Has your trailer ever reach -10? Some just can't do it, for many reason. My father and I have the same trailer, but still slightly different. His struggles to pull to -10 where mine will get there no problem. Our old trailers (I have an 04 Wabash) just aren't going to be as good as a new one, for many reasons. Unless you're trying to haul ice cream with yours, I wouldn't worry much about -5 versus -10. Plus STexan was pretty spot on, temperature of your product when loaded plays a big role.
At 90 degrees outside, I won't even bother setting -10 on my unit. Once it cools down outside, then drop it more.

 

I was about to ask if your trailer is empty,considering that an old trailer looses a % of its insulation efficiency,it might be normal.

 

With almost any reefer---sans some of the very heavy spec'd ice cream units---you are asking alot for it to drop 80-90 degrees(90 degrees outside--could be over 100 inside)in a short period of time...so the length of time it took you Everett doesn't surprise me at all--no biggie if you have that kind of time and $$$$ for the amount of fuel you burned---Although it is more labor intensive---it is much more adviseable to step the unit down gradually--5-8degrees at a time---the unit doesn't work as hard and especially doesn't defrost as much---with an temp differential that great between unit discharge temp and ambient--the unit is going to freeze up much sooner--due to the amount of moisture created by the temp difference---these causes the unit to kick back into defrost cycle an a very regualar basis--which of course raises the discharge temp(warms)in order to melt the ice buildup--which also causes more moisture as well as eliminating most of the temp reduction you have already accomplished.....personally Im really ###### about precooling---especially in the heat--its a scam...but that is a whole different issue...

 

Is that an sb210 or 230? The 230 has more BTUs and will make a difference. Is the trailer a 2005 as well? Over time insulation does lose its effectiveness. If freon is good the ETV could be bad. Had one like that once and the ETV was not letting enough freon into the system.

 

Just don't forget that a 2005 trailer (11 years old) will have the insulation degrading enough that cold temps may be hard to reach.

But also you may have a bad sensor.

Try putting in a couple thermometers in the front and read of the trailer to see if it is actually reaching the temps you set it at.

 

I'm pulling mostly new Great Danes (2016) and it takes about 3 hrs to get them down to -10 from 80+ with a Carrier.
Had older Thermo King Utility trailers and it was a pain in the ### to get them down to -10.
The humidity is still a factor, when I'm in the desert they hardly defrost, here in Nebraska they are defrosting all the time.

 

I'm pulling a 2016 Utility with a Carrier, picked up a -10 load in Atlanta (outside temp was 100 rolling down the road), my unit was running on high from the time I closed the doors at 2 pm until after I went to sleep at 9 pm in Monteagle TN when the outside temp dropped below the mid 80's. It finally cooled down to -10 and cycled like normal.

 

As stated above your reefer may be running fine but the insulation is no longer effective.. I've pulled trailers that struggled as well and most times just by walking along outside of trailer and touching walls you find many cold spots which means insulation is shot ps on frozen loads I always plug water drain holes with rolled up plastic it's amazing how much cold air comes out of them

 

Did you check the temperature of this load as you were loading?