reefer unit question...possible issue

frozen loads, I pre-cool to 20*F and that's it. Why bust my reefer on an empty trailer.

I pull it down the rest of the way on continuous. Just seems to be easier on the unit after it's loaded.

 

Most single truck or very small carriers don't use the intellisets. They either know what to set the machine at, either based on the bills (preferred) or look it up in the USDA guide or the like. That feature is targeted to fleets that haul the exact same commodity all the time and don't want their drivers thinking too much.

MN: I once believed the same as you about continuous mode being less stressful on the equipment. I got a Carrier tech lesson (free for a change LOL) while working through a problem last week (long story, but a broken condenser fan shroud was causing poor cooling performance, and later, a high compressor discharge temp alarm and shutdown, but only when parking). Turns out the fresh protect logic (enabled in continuous mode) was working against me, ultimately contributing to the problem. Less efficient heat transfer, lower condenser fan speed, and frequent defrosting were adding together to create a struggle. Parking with the truck blocking the front of the unit, no more air flow, and heat boiling out from under the truck, was the last straw to set the compressor temp alarm.

The only time it makes sense to run a frozen, or even non-sensitive fresh load like raw meat, on continuous is if you can't sleep thru engine starts or are trying to be a good neighbor at a truckstop. The cycle mode is actually less stressful on the equipment, despite the higher engine speeds which happen to make things work more efficiently. It's counterintuitive, but when you really think about how the components work and transfer heat, it makes sense.

I would agree with a modest pre-cool setting for frozen. I do that too at shippers I can get away with it. I'll usually put it on +10º cycle and just act like I didn't know better if someone challenges me. Then of course set according to the bills or product when I shut the doors. Although on frozen settings, any box temp under +20º will usually get you on a door or out the gate at most places.

 

Only if u have bad box.....

 

Ok I think the op point being missed here w/all talk of precoolin etc.....he is/was not talking bout a load already @temp he was asking
Discuss in a produce load picked up hot--that needed to b cooled in transit 2 totally different worlds--precoolin a trl and load in hot product will not aid in anyway to cool the core temp of the product any quicker....so especially 4 those NEW 2 haulin field produce.....this is a very important distinction

 

Trancicold carrier is way better for frozen loads then TK...cools faster....

 

I m talking about common carier 2100....u can't compare it with sb300 cause sb300 has bigger compressor. ...but can bet my money that carrier 2500 is a way better for frozen loads than sb300....k