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Here is my delima!

C64 gets ice cold, replaced thermostats with three I have on hand in shop, replaced the starter with a new 3 in 1. Machines runs and gets cold, does not shut off unless I manually turn off the thermostat. It got down to 16 degrees, it short cycles compressor will kick back on and only run for 30 secs up until a minute then shuts off.

Any ideas?

three bad/used thermostats maybe, or the wrong ones, (IE: The evap' coil direct contact type vs air temperature sensing type) for your medium temperature application,

How do you tell the difference? get a tall glass packed with ice & add some water then take your "T-stat" & set the range to about 1/3 of the dial travel past Off, ( about #3 if the dial is marked with numerals) then dunk the sensing coil end ( or sensing bulb/tube) in the glass of ice water, you should hear it "click" off, then take it out & warm it with your hand & it should "click" back On. if it doesn't, then it's either bad, or it's designed to operate at a lower temperature range.

You can also use a quick go/no-go test to see if it's a lower temp sensing type by spraying the sensing bulb/end with a squirt from an upside down container of "canned air" used to dust off keyboards & such, use caution as it will chill down to -45 Degrees F & give you a quick case of frost-bite if you spray your fingers.

Thanks for your help, I nailed down the problem. The original thermostat was working great up until today, I had another tested thermostat that has been laying in a parts bin for years it failed me as well, as with a brand new one that was new out of the box, I pulled one off of a parts machine and she runs, cools, and cycles like she should.

Thanks!!!