SMC Discussion Areas

Ok,
I've put in Many, many new thermostats over the years and fired up the machine and was able to get the range of cooling i needed just by adjusting the dial.

I am restoring a VMC 72, it's all done, reworked cooling unit with a brand new Thermostat... Non Contact style

First test run on setting 1 would get 30 degrees and it just won't shut off...

obvoiusly setting one, I don't want that cold.. maybe 50 or so... I usually find the optimal cooling around 3-4 on the way the Thermostats as set from factory.

so now I started messing with cut in and out points and I am having issues..

can someone explain the cut in and cut out... and the best way to adjust.. I thought it I could figure it out but just got a case of the stupids for some reason?

Thanks!

John

Adjust the #1 knob setting to 32 cut-out and 38 cut in. Each setting on the knob should lower the cut-out by 2.5 degrees. The cut-in should never be below 34 degrees so the evap can defrost.
You should also account for altitude and adjust the cut-in & cut-out accordingly by raising it to suit the altitude.
Not sure on your brand of t-stat, but according to one of my manuals each full turn of the adjustment screws changes cabinet temp by 4 degrees.
I'd adjust the the cut-out first and then concentrate on the cut-in.

Thanks Tom,
But another question.. the therm i got is one from Funtronics, pretty simple basic therm.
I have messed with the screws so much now, not sure where they should be at .. so if I turn them clockwise all the way closed, I'm assuming that is NOT where they need to start at ? is there any way to know where I should start them at? maybe 6 turns out or so? I think each has at least about 12 turns Counter clockwise till it stops or comes out.
Plus shouldn't setting number one Not be the coldest temp? as when you turn it up to higher numbers it says "Colder" right on the dial.?

I'm asssuming it's just a matter of playing with it, but don't have alot of time to just sit there and wait for it to cycle...

I had this conversation a few months ago with Eric at Global Compressors.  First, the main issue is the Mexican-made stats, well, stink for calibration.  I have a water-bath cooler that had the opposite problem.. it wouldn't get cold enough.  I did basically the procedure Tom talks about, except I turned the screws the opposite way.  It worked.

The cut-out (temp at which the compressor kicks off) and cut-in adjustment (temp the compressor kicks on) is as follows:

Clockwise = lowering the temperature
Counterclockwise = raising the temperature

Sorry, John, but I don't know what the exact starting point is for the screws, but I do know it isn't all the way in.  You could wind each all the way in and then wind each out 6 turns (provided 12 turns is the full range of the adjsutment) to start at the middle.  That would leave you equal adjustment each way.  I'm just speculating here.

Number 1 should be the warmest setting on the dial.

Ok,
Thats what I was thinking too...
yes Mexican therm... funny though is it is the first one out of how many I've had issues with? oh well.. i'm sure I'll get it .. just looking for a quick fix  I guess

That is exactly what I wrote....you want setting #1 to be 32, turn it to #2 for 29.5, #3 for 27 and so on...
The cut-in is the temp you want the t-stat to kick the compressor back on - this setting should never be below 34 degrees so the exap has time to defrost (I think 37-8 is normal). The cut-in temp is constant and not altered by turning the knob from 1-9.
Think of cut-out as breaking the circuit and cut-in as completeing the circuit.

It is going to be a trail and error...I agree with Wayne - start in the middle and find your way. I would probably try adjusting cut-out first - then cut-in.

Thanks guys,,, with some adjustments and checking back in at home (advantage of only working 1 mile from home) about 5 times yesterday I got it adjusted and cooling properly!  :happydrinkers: