Refrigeration Solution

[Wandering Star]

This has to be a very vague cry for help as my V27 is in Mallorca and I forgot to make notes before I flew home. I'm flying back out mid July and would like to source any part I need before then. So here goes.

The V27 is fitted with a Bukh 24 engine and slung on the side of this is a fridge compressor belted off a second pulley. Inside the fridge is what I believe is referred to as a holding plate? from memory it's about 14" x 10" x 3" - a sort of rectangular stainless steel box which should freeze up and remain cold, I've seen the same frost covered holding plate at boatshows. I've never used this system in my 6 years of ownership.

Midway between the engine driven compressor and the holding plate, there's a small black box with a switch, a couple of LED's and inside, a small PCB. This little black plastic box has Thermocool printed on it and is damaged physically and broken electronically. I've done a Google to try and identify the box but with no joy.

I think (I don't know) the box is probably used to electronically engage or disengage some sort of clutch device between the compressor and the engine, tracing the wiring would tend to support this idea - does that sound reasonable? If that's all it's doing, could I replace the box with a simple on/off switch? What are the LED's for? what's the PCB for?

I don't want to blow anything up so I thought I'd ask for advice here before I try a repair! I'm sure the system will also need re-gassing too but I'd like to get the basics working first.

Ta everso.

Cheers, Brian.

 

[rob2]

It depends on the type of compressor in use. My experience is with Sanden compressors, which are originally designed for automotive air conditioning, but frequently used as fridge compressors - particularly used with a holding plate. Can't say off hand how the control box is designed but the only thing it can control is athe electromagnetic clutch which connects the drive pulley to the compressor. Typical systems used the SD type compressor.

http://www.sanden.com/index.php?tag=U5H0AMX7Q

Rob.

 

[owen-cox]

From my experience I would recommend the following. There should be a high pressure switch in the cable line that goes to the compressor clutch. it should be on the pipe between the compressor and condenser or on the top of the condenser ( the sea water cooling part) You ABSOLUTELY MUST include this switch in any power you put to the comrpessor or the compressor will run constantly even if there is no sea water cooling. This will certainly make the compressor seize up. I have had this happen 30 miles from shore with nervous clients and black smoke billowing out of the engine bay does not inspire confidence! I recommend the following find a fused DC supply 12 or 24V depending on the coil voltage of the compressor clutch and install a mechanical run back timer. such as :http://uk.rs-online.com/web/p/time-delay-relays/5362779/ then run the cable from the supply to the timer then to the high pressure switch ( sometimes there is also a low pressure switch and this can also be linked in) then to the clutch. This will mean that the compressor can run and will not run for too long and has all the correct protection. if it hasnt frozen the plate after 120 mins there is something wrong with it. you can always run the compressor again on long trips but the plate should maintain fridge temperatures for 12 hours or more when frozen depending on the insulation of the fridge cabinet.I hope this helps I can always help out with a diagram if required.

 

[Wandering Star]

Sorry this thank you post is late fellas and thanks for the advice. I think on reading the advice though, this is probably one of those jobs where I'm safer calling in the experts, the system almost certainly needs a service and regass in anycase. I'm sailing from Mallorca to Algarve in a couple of weeks time and I'll get someone in Lagos to look at the whole setup. In the meantime I'll just have to carry on drinking warm beer.

Cheers, Brian.