Originally posted by dorrmann I've seen it before on smaller applications. I don't know if it'll cause it to freeze because the smaller cold controls come in so many different temperature ranges, it could or it couldn't.
In my opinion, the best place to put them is in the return air stream so it senses the warmest air.
Delta is right.
Placing the bulb of a cold control in a small self-contained case will result in case ice ups, unless something else is done to defrost the evaporator.
Most cold controls (OEM) are designed within a range of evaporator temperatures approximately 10 degrees below the desired box temp. (IE, If you want a box to hold 36 degrees, the coil will need to be run down to 26 degrees.) Now, the majority of these controls are also "constant cutin", which means that they will always cut in at a factory set evap temp, like 41 degrees. That way, all frost is removed from the coil before the next refrigeration cycle begins.
On larger, remoted boxes, walkins, etc., the temperature control (NOT "cold control" at that point.) should be mounted in the center of the inlet of the evaporator coil. (Returns are on air conditioners...)
On these larger boxes, a defrost timer can, and should be, IMO, employed to defrost the coil(s) at certain intervals, usually every 8 hours. Sometimes, pressure controls are cobbled into this service, by having their cutins set high.
Pressure controls should be used as safeties only, and temperature controls and defrost controls applied as operating controls.
There are other ways, but when you're talking small cap tube self-contained cases, the constant cutin cold control is the single best way to control temp.
And worn out door gaskets too! Check them carefully. I think a few guys on this board have a couple of blown gaskets from time to time. And the gaskets are easy to replace, easy to get and fairly good money. I bet 72.3% of all the samall door gaskets in every restaruant and every convenient store are worn out or broken.
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