Help with TK VM-405 PBBD2

[Reeferman27]

Hello fellow fridgies.
Can someone help please. I have 3 TK VM-405 transport units put in small insulated containers used by US military in Afghanistan. 2 worked fine but the 3rd showed no signs of life even though there was good power supply. I traced the fault to the thermistor unit in the compressor and linked 9E and chm and it started working, and has done for 3 weeks but now the comp. is tripping the mcb. and another unit has gone the way of the 1st.
1) what is the reading for the internal compressor thermistor( between 2 orange wires)
2) What is the compressor motor windings ohms reading.
Cheers in advance

[chillerman2006]

Hi Reeferman

I dont have the exact ohm readings for you, but if you meggar all compressor terminals to earth & between poles

will be able to tell you if readings sound ok

So far it sounds like your compressors are down, as to link out thermistors & then start tripping breakers after a couple of weeks of run time, sounds pretty conclusive mate

If you have another unit there which runs ok (good thermistor) I would check the readings on that, they should then be roughly within 10% on the failing units

R's chillerman

[Reeferman27]

Thanks for the reply.
I had tried that but they all seemed to be the same. The first had signs of water ingess into the comp. box which led me to believe that the thermistor unit was at fault, but now the 3rd on has gone the same way. I have called the sparks to check the power from the generators. I don't suppose them being stationary in direct sun in 38C+ ambients trying to pull -20C helps too much, especially with idiot cooks in and out all the time.

[chillerman2006]

Them temps + radient heat does not help, maybe when you get things running again you could lower the superheat, allowing for more cooling for compressors

And yes generated supply that is un-even or below whats required will take your compressors out

R's chillerman

[Reeferman27]

Good day one and all.

An update. I have finally got round to having a proper look at these 3 units. I suspect the first has seized due to excessive heat and load, me bypassing the safety didn't help. :confused:

All the comps. are as follows- between windings- 1.7ohms, windings insulation to earth- more that 200Mohms@1000v. The thermistor (OR-OR) 179 ohms at +32C ambiant, although probably warmer as still sat in direct sun!!!!! CHM-9E conections on block- open circuit and between HA-HA2 4.2Kohms(all with wiring disconected). I suspect in the last 2 the thermistor block has failed.

TK don't list the thermistor block as a separate item so I'm off to see if I can find some information about these thermistor blocks.

Thanks for all the assistance now and in the future.

[Reeferman27]

Found this- http://www.kriwan.com/en/Protection_and_Controls-Products--25,productID__994.htm

It may help others.