Friday, Apr 23, 2010 at 11:14
"Normally the thermostat will shut off the solenoid at temp, then the compressor pumps down and stops when the suction pressure around +1psi and LP cuts out.
If the compressor runs "continuously" without refrigerant rather than short cycling then every Engel that loses gas would have a compressor failure also due to no lubrication and sucking into a vacuum wouldnt it? "
100% correct, in a commercial cool room/freezer situation. Also, you can control the fridge temp via a LP control, without a solenoid, by setting the cut-out at a setting that corresponds to the temperature desired in the fridge. (Not for capillary systems, more for tx valve.)
But the most common form of control is a simple thermostat that operates the compressor. No pump down. This is the system that is in most domestic fridges, and also used in the Engel, Waeco and Trailblaza fridges, although in these the thermostat actually operates the compressor via the electronic box. The down side is, as you mentioned, the risk of compressor failure due to overheating with no refrigerant return to cool the windings.
"Sorry not questioning your knowledge but trying to get a handle on how these "iconic" fridges work."
No need to apologize fisho, you had a question and you asked it. And you asked in a way that can't be taken offense at.
"It would seem to be a very crude system if this is the case?"
Crude, yes but popular. Keeps the manufacturers cost down, wall mount split system air cons and window units mostly don't have any safety pressure switches either..... the only one I have ever seen was a Benson unit, that runs R290, which is basically, BBQ gas. (I worked on one, and one only. I will never work on another one!)
Hope this helps....
Cheers
Brian
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