reefer unit question...possible issue

engine coolant alarm on a thermo king will go off with the unit just a half gal low on antifreeze

 

Just my process when picking up produce....especially hot out of the field.

I step it down in 5 degree steps. If it pulps 80, I start at 75, let it cycle a couple times and hold temps. Then 70 till I get it to the temps I want. If Iset it to continous, it runs on low idle instead of screaming on high idle.

 

Glad I read all B4 reply--Mndriver Hit it--you ARE NEVER going to cool hot load--by just setting temp--esp when HOT out--all the unit does is kick into hi speed--freeze up and go into defrost--over and over--
with a protect load like that(u really arent tryin to make cold)
FIRST--PULP the onions and get a TRUE TEMP READING---then set unit 5 -7deg lower-on cont-close up--and VENT REAR(I hopin ur trailer has a vent door--if not u really gonna work it!)
U r a little luckier here--since in this case u have a carrier with a better readout box--and it will show u when it kicks into warming mode--so u no when to stop and set cooler
Now unfortunatly alot of the newer style readout boxes just show green or on so it is a pain)
then run down the road for a few(LEAVE UUR DRIVERS WINDOW OPEN AT LEAST A LITTLE--U SHOULD BE ABLE TO HEAR FEEL UNIT--slow down(out of hii speed) then find a safe place to stop--and set it down a few more degrees--repeat process--welcome to produce hauling---LOL
Now this can be done a few other ways--BUT--you have to always have the same wagon--and u can modify the unit and change the readout box to make you life easier--Good Luck

 

Thanks for the genius advice. Since I'm not paying your claims, set yours however you want.

Now next time you're running a +50º produce load on cycle, check your outlet temp about 20-30 minutes after you shut the doors. Not the big numbers on the display. You have to go into the data function to see that one. My 10 yr old Carrier with 18k hours on it will be approaching zero already. Do the same check in continuous run and the outlet temp will only drop to return temp minus about 15º, and stop dropping around 3º below the setpoint.

That's also known as "fresh protection" logic. Outlet temp is adjusted by the controller to the difference between outlet and inlet temp when initially cooling down on continuous mode (versus shooting for an absolute setting on cycle). It also means I don't have to pull over every hour and dial the temp down a few degrees. The reefer does that gradual outlet temp reduction automatically. If you're still doing that with a reefer that's less than 10 years old, you might want to check your settings and maybe save yourself some stops. If you only want a 7-10º drop when cooling, you can probably change that setting or have a dealer do it if it's not in the driver settings.

 

You talking the "product shield"? Fuel econo No is one setting. None of them are user settable.

I show 5 settings for "Fresh Protect" too...."A" through "E" and no way to see what those settings are.


Found this too...It's about 31 minutes long too.

 

Yeah I'm sure I got the terminology wrong, and only quoting results from my units. The gist being that (probably in most cases) it's assumed that a continuous setting is expected to be used on sensitive cargo, cycle mode on anything that's not affected by a freezing blast. Probably varies across models as well. I looked it up in the operator manual for my '04, and it's custom program capability is called "Intelliset." Presumably so a carrier doesn't have to depend on the driver to actually know anything, but be able to read and just match the setting name to the product they saw go inside. Onions got loaded? Choose "onions" on the menu, set it and go.

A quick scan and I didn't see any phrases like "product shield" or "fresh protect." The latter was what a Carrier dealer tech used when discussing this topic a while back. Could be they're used in TK literature and trademarked LOL.

 

I was mistaken. "Fresh Protect" is buried in the "Functional Change (Parameters)" menus, along with a number of other settings related to how the unit operates under various conditions and settings. This is exactly where you choose how far off the return air temp the unit will permit the outlet air to vary. You don't change the temp values, instead choose one of the A-E presets.

 

So understanding that better....

If I want to set it for 55*F, with my fresh protect set to "B" or "C" (it was on "C"), set it for continuous, it's going to walk it down for me instead of redoing it every 5-7 degrees.

(All this falls under, "Understanding your equipment")

 

That's how mine was behaving, probably due to age and a broken condenser fan shroud I am having repaired at the moment. However, the way this reads, the unit should run below the setpoint, not the return air temp.

So for example, start on a 100º day and set at +55º on setting "B" you will get discharge air temp between 48-51º until the return air temp approaches the setpoint. Then there are other parameters that determine how rigorously the unit tries to stay on top of the setpoint.

So managed to clear my own misperception by RTFM LOL