Reefer has difficulty to reach -10 temp

How is the condition of the Floor? Cold air will settle low and leak out from the floor if this area of insulation is degraded. eh, try this, walk across the floor, will the floor move as you walk upon it.

 

It should be able to hold -10 with no issues. Now -20 is hard on the reefer to maintain. I always find that running on cycle mode maintains the temp better than on continuious.

 

the person i haul for, told me to plug all 4 holes up in the floor....especially running thru Las Vegas......

 

I had a load to pick up and the boss said to set temp at ..... - 10 ... the refer got down to ... 20 ... as I was backing to the receivers door and shut down, which we found out later was do to a lose belt and a bad head gasket.

 

Very good point.

 

I have a 2004 thermo king sb190. Doesnt have trouble bringing down temp to 25, but when set to -10. Never gets there. Got to as low as 8. Then goes back up to as high as 29. When defrost kicks in. Should it go that high even if its set at continous?

 

A unit that old could have many multiple problems if it hasn't been well maintained. Even on a hot summer day, with doors shut (and not parked in a dock) an old reefer should be able to get below zero at least within two hours with an empty box, whether it's on continuous or cycle really makes no difference.

If it is defrosting that often (like every 15 or 20 minutes) with the door shut, you definitely have some major issues.

 

If you're trying to get to any point less than 20f, always run cycle sentry (start/stop).

If that still won't pull it down, you have problems with your unit.

 

Sb190 is a produce unit
Not really built for ice cream in summer desert

Plus a trailer that old has lost a lot of its thermal efficiency

I would recommend not doing frozen loads with this unit outside of winter, produce and meat it should still be fine

 

98 degrees here in texas im at 2.5 degrees the load is supposed to 0 degrees. I got it set at -20 and 2.5 is the best it can do in this heat. It hit 0 last night so its probably normal for older trailer