I've been working in the refrigeration industry for 10yrs or so, and as a service and maintenance engineer for the last 3yrs.

I get by fine using the techniques i have picked up along the way but i feel i could better myself massively.

Unfortunately i don't have anyone to look upto as a mentor so i'm finding it hard to progress as an engineer.

I would like to learn how to use subcooling and superheat as a diagnostic tool.
I've been looking up on it through text books and the internet and have found some helpful stuff, but when attempting to put it into practice today i struggled.

I was working on a freezer cold room.
The evaporator had excessive ice build up in patches.
Ice was forming at the top left (inlet) and in a V shape in the top centre. Also the the TEV and surrounding pipes were covered in ice but i don't see that being a problem.
I forced electric defrost and manually defrosted with warm water. Checked defrost settings on controller and found 0 drip time. I adjusted to 10 mins.

After doing all that i thought i'd check the subcooling.
I connected my gauges to the liquid line access port and taped my thermometer probe to the liquid line near the condensor.

Liquid pressure was 12 bar, so 26c in temp, with an ambient of 14c.
Liquid line temp was 30c.
This confussed me as it seems to of GAINED 4k rather than lost any???
Suction pressure of 1 bar.

I know the liquid pressure is low and i have suggested fitting a fan speed controller, but would this effect the subcooling?

The system is coming down in temperature very well and cycling as it should do.

I didn't get round to checking the superheat as i would of had to take the evaporator casing off which was a bit of a task and i was running out of, what with it being a Friday!

I've got literature explaining how to measure subcooling/ superheat and what temperature differences to expect but nothing about abnormal readings.

I know i should know all these techniques but have forgotten them from my college days and have not had much guidance/help from my employers.

If anyone has any answers for me i would be very grateful.