Thermoking Trailer SR2 and SR3 controller anyone can explain the modulation cool and

Hi anyone can explain the modulation cool and heat on Thermoking Trailer with SR2 and SR3 controller with optiset plus profile. I have an issue where banana freeze on a 14°c setpoint the driver said it pull down to minus temperature. I have done a full download suspecting the fridge have had a modulation issue but base on full download doesn't show any modulation issue all temperatures are normal. Can anyone with a wide knowledge with Thermoking explain it want to learn and understand more this operation and features of this unit.

The first point to check is the sensors are reading the correct temperatures,

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Originally Posted by cadwaladr

The first point to check is the sensors are reading the correct temperatures,

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Hi sensors reading are all good.

Does the unit defrost ok,you may have a problem with the three way valve not shifting to the heat position the valve is controlled by the pilot solenoid ,if it does not energise then the three way valve will not move to position.

Quote:

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Originally Posted by cadwaladr

Does the unit defrost ok,you may have a problem with the three way valve not shifting to the heat position the valve is controlled by the pilot solenoid ,if it does not energise then the three way valve will not move to position.

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Yes it is defrosting. On positve setpoint has an issue but on frozen setpoint don't have any problem.

On the download does it show the solenoid valve being energised when set point is reached,when it's set on a positive setting

if its set on + 14 and its pulled temp to - figures then its stuck in cool.
This could be as simple as the pilot solenoid not energising. So when it calls for heat, just carries on cooling.
The modulation will only affect top load freezing.
I.E not blowing out air so cold as to freeze the bananas situated at the top of the load.
Can't see modulation having anything to do with it.

It seems like heat was locked out,it defrosts ok so pilot solenoid seems to be working it would be good to look at a download. When the freezing took place?

Is it running in continuous or start stop?
What does the download show the discharge air temp?
I'd pull the optiset file out and have a look at it. See what the floor limit is set to. Floor limit is lowest temp it will allow the discharge air below setpoint. I'm pretty sure this is only in continuous. In start stop it will run in high speed pull down and ignore top freeze completely and get to temp as fast as possible and cycle off.