I had a similar problem with an isotherm
SP fridge system - manual attached
The evaporaoir stopped cooling
even though compressor was running. Also, it ran low amps (<2A).
I purchased a refrigerant sniffer from Amazon, and found the leak. It was a large hole in the tube to the evaporator, caused by fretting where the tube (unprotected!) passed through a bulkhead.
My isotherm system has what I think is a pair fairly standard couplings on the evaporator tubing that allows easy installation
of a new evaporator and tubing, without having to drain the compressor of refrigerant.
I bought a new evaporator from https://coastalclimatecontrol.com/
for about $200
From Harbor Freight I bought a refrigerant vacuum pump
($90) and , and a can the appropriate refrigerant from Walmart
Note: standard automotive fittings do not suit the Danfoss compressor.
I used a gauge/manifold/adapter system to connect
The unit is longer sold by HF, but is similar to this on Amazon
was easy - the coupling require wrenches. I made sure that the tubing isprotected where it goes through walls.
I used the vacuum pump
to pull air out of the system overnight, and added refrigerant until the compressor pulls the correct amps.
That was 6 months ago, and all is well.
If you are located near Kemah
, TX you're welcome to use my pump & adapter