Author Topic: Frigomatic compressor fails to start  (Read 8059 times)

misterg

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Frigomatic compressor fails to start
« on: July 21, 2013, 05:22:39 pm »
Hello Richard - Firstly, many thanks for the depth and breadth of advice to offer here.

Secondly, the Frigomatic system on our boat has stopped working:

I'm not sure of the exact model (maybe you can identify it from the photos?), but I assume it is a Danfoss unit as it uses a Danfoss 102N3030 12V controller and may date from 1995.

It is keel cooled, without any water pump and the small coolbox has what I think is a holding plate. Until last year, it worked fine.

The symptoms are that when powered up, the electrics emit two short squeaks, but the compressor usually doesn't start. I have had several false dawns looking for poor connections in the electrical supply where the compressor has run after I have re-made one connection or another, but the symptoms return once the compressor is stopped. Most recently I have replaced the batteries with no improvement, and the symptoms seem to be the same whether or not the engine is running, or the charger is on or not. Voltage at the unit is in excess of 13V and drops by 0.5V during the attempted start. (I am mindful of your comments about voltage spikes, etc.).

I have installed a diagnostic LED between terminal C & D on the controller, and have a link across the thermostat connections, but I am having trouble interpreting the LED as it mostly stays on.

This video shows what happens. In the first part of the video, the multimeter is showing the current drawn by the compressor, and the diagnostic LED flashes (twice??) - it is possible to hear the squeaks if the volume on the video is turned up (all noise is from the fridge - the meter doesn't beep). In the second part of the video, I have connected the supply straight to the controller, and although the electric still squeak, the diagnostic LED just stays on.

http://www.youtube.com/watch?v=jQ1hI6BE7Ug

On one occasion when I had the meter connected, the compressor started and I ran it for about an hour. The current started out at 8 amps and gradually dropped to 6.4 amps over about half an hour, where it remained steady. The larger pipe into the keel cooler was hot (just about bearable to the touch), the smaller pipe was warm, and the holding plate iced over. When I stopped and attempted to re-start the compressor, it was back to the behaviour described above.

The label on the side of the compressor has "Running current [  5A  ]"

I measured the resistance between the 4 terminals on the compressor and got 3.8 ohms from the top pin to both left and right; 3.6 ohms from top to bottom; 0.2 ohms from both left and right to bottom; and 0.4 ohms from left to right.

Nobody has touched the refrigeration circuit.

I would be most grateful of your experience in interpreting this - Is something faulty, or do I need to continue my quest for poor wiring?

Thanks in advance,

Andy

(The attached photos are also here at higher resolution:

http://s255.photobucket.com/user/werdnayarg/library/webstuf/fridge?sort=3&page=1  )

Edit to add that I am in the UK, and it was a hot day for us when I was doing these tests - maybe mid 80s F in the cabin
« Last Edit: July 21, 2013, 07:22:00 pm by misterg »

Richard

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Re: Frigomatic compressor fails to start
« Reply #1 on: July 21, 2013, 08:03:51 pm »
It looks like compressor is a four pin BD3 and LED is connected Backwards. LED ground is to be connected to D terminal.

Trouble LED on 4 pin modules will only indicate a voltage drop if connected correctly. On this unit you should never see LED to light up unless the is a low voltage spike. Low voltage code is one flash repeated every 4 seconds.

Is there any thing connected to Module terminal F ? If so disconnect it and see what happens?

Is this unit supposed to also run also on AC power?




misterg

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Re: Frigomatic compressor fails to start
« Reply #2 on: July 22, 2013, 06:40:42 am »
Many thanks for the reply:

I have double & triple checked, and am as sure as I can be that the -ve (cathode) of the LED (the side with the flat) is connected to 'D', and the +ve to C+. (I checked another LED from the same bag to make sure that the side with the flat is the -ve).

I have attached photos of the module, and the LED connections in case I am overlooking the blindingly obvious! The LED leads are clear of the board, but I had put some tape underneath just in case. I have removed the tape to double check for shorts, and all appears to be in order. The behaviour is the same after fitting the LED as it was before.

Nothing is connected to F (nor C+ or D before I fitted the LED). There is no fan, just the through-hull cooler. The thermostat / shorting link was connected between T and C.

The unit is 12V only AFAIK (there is certainly no AC connection to it, just 12V power & the thermostat).

Thanks again.


Richard

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Re: Frigomatic compressor fails to start
« Reply #3 on: July 22, 2013, 07:39:26 am »
Sounds like it is time to try another module.

misterg

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Re: Frigomatic compressor fails to start
« Reply #4 on: July 22, 2013, 09:22:00 am »
OK, thanks very much for that.

Do the current readings I took when the compressor did start give any indication as to the health of the rest of the system? I would hate for a failing compressor to take out a new module, or to put more money into an installation that will have to be replaced in any case.


Richard

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Re: Frigomatic compressor fails to start
« Reply #5 on: July 24, 2013, 04:36:30 pm »
1. If you placed Jumper across module terminals C and T.
2. Disconnected Wire From F terminal.
3. Run correct size and correct polarity fused jumper wires direct from a fully charged battery to module in order to bypass all boat’s wiring. Volt meter readings are of no value, Compressor still does not run electronic module needs to be tested on another unit or replaced.

If 1,2,and three did not get unit to run I would be suprised because this works anytime compressor will not run.  AND DO NOT REPORT BACK THAT VOLTAGE IS GOOD unless you have Superman's eyes.

misterg

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Re: Frigomatic compressor fails to start
« Reply #6 on: July 24, 2013, 05:34:53 pm »
Understood  ;)

I will report back.

Thanks again for the help.

misterg

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Re: Frigomatic compressor fails to start
« Reply #7 on: July 29, 2013, 05:38:03 pm »
1. If you placed Jumper across module terminals C and T.

Check.

Quote
2. Disconnected Wire From F terminal.

Check. (Nothing connected in any case)

Quote
3. Run correct size and correct polarity fused jumper wires direct from a fully charged battery to module in order to bypass all boats wiring. Volt meter readings are of no value, Compressor still does not run electronic module needs to be tested on another unit or replaced.

Check.

Behaviour is unchanged with jumper wires direct to battery (properly made connections, etc, and ammeter out of the circuit) - the LED is always on, with just a screetch from the electronics every 30 seconds.

I changed the module for a replacement from Penguin Refrigeration ( link ) and the compressor fired up OK each time, so it looks like the module was faulty - thanks very much, but please read on:

I then put the ammeter back in the circuit, and got the following currents:


Time  Current
(mins) (A)
0       5.8
2       6.1
8       5.2 (dropping rapidly)
9       3.8 (then rising rapidly)
11      6.0
12      6.5
13      4.5 (dropping rapidly)
14      3.5
15      3.3
19      3.2
23      3.1
35      3.0


Unfortunately, I didn't have enough time to run the compressor for more than about half an hour.

At the beginning, the pipes to the keel cooler were warm/hot, but when I checked at the end, the were both cool. Compressor was hot, but the cold plate only had condensation on it - maybe I was expecting too much in half an hour (this was all with the t/stat connections jumpered).

Do those current readings look ok?

Richard

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Re: Frigomatic compressor fails to start
« Reply #8 on: July 31, 2013, 10:41:26 am »
Amperage at 11 minutes would indicate refrigerant volume OK to slightly low 8 amps is normal in 75 degree F seawater water temperatures. Actual volume of refrigerant would be indicated after unit runs 2  hours by percent of evaporator covered with Frost.

Amperage dropping to 3.3 in 15 minutes indicates either cold seawater has reduced gas pressure volume or there is moisture freezing and thawing in capillary tube. If frost does not appear on part of evaporator and there is only cold condensation after 1 hour I would suspect moisture in refrigerant. If compressor is a BD3 it has Ester oil and extensive dehydration with vacuum at 200 micron for 4 hours is required. Extensive vacuuming means complete system must be warm during dehydration as this new oil does not release moisture as easily as the old Mineral did.

misterg

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Re: Frigomatic compressor fails to start
« Reply #9 on: August 01, 2013, 09:17:27 am »
Many thanks!  :)

I haven't had the chance to run it again for an extended period, but it will hopefully be OK.

The water temperature here is more like 60F than 75.

I understand what you are saying regards frost coverage on an evaporator, but is there any equivalent test for a holding plate? (I assume that this is what I have - see photo.)

Thanks again,

Andy

Richard

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Re: Frigomatic compressor fails to start
« Reply #10 on: August 01, 2013, 11:15:19 am »
I have not seen a holding plate like that before but dropping temperature of eutectic material inside with a fixed speed Danfoss compressor will take more than one hour to freeze plate.

Your test at 15 minutes shows compressor is working correctly and refrigerant quantity is good.

One of my test stands is much like your system fixed speed BD3 compressor and a eutectic solution holding plate. My system at 15 minutes and warm plate draws 5+ amps and stays at 5 amps till plate solution is at zero degrees F with a good plate frost cover 3 hours later. If my plate were in an insulated box like yours amperage would be around 4 amps when plate was frozen solid.

What I can not explain is why at 15 minutes your test indicated only 3.3 amps of actual work being accomplished.  It is possible that there is moisture freezing in cap tube if so no matter how long compressor runs frost will not form on plates surface there will be only 33 degree F condensation. And the hissing spray sound heard in a normal box will come and go every few minutes as ice freezes and thaws blocking and releasing refrigerant flow..

misterg

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Re: Frigomatic compressor fails to start
« Reply #11 on: August 01, 2013, 05:16:16 pm »
Thanks - I clearly need to run/monitor it for a longer period.

Your assistance is much apperciated.

Richard

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Re: Frigomatic compressor fails to start
« Reply #12 on: August 01, 2013, 07:12:18 pm »
Another explanation for amperage to drop so quickly is loss of part or all of eutectic solution from plate. If some solution has leaked out there will be a level indicated by height of frost ring.

misterg

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Re: Frigomatic compressor fails to start
« Reply #13 on: August 31, 2013, 07:52:03 am »
Just to update this:

I had the fridge running for extended periods recently.

Initially, I got nothing more than cold condensation on the cold plate for 6-8 hours. The compressor was running constantly and hot, but the pipes to and from the keel cooled were cold (I didn't have any means of measuring running current).

I left the compressor off overnight, and tried it again the next day in the pathetic hope that something might have changed:

Very quickly there was frost on the holding plate, and it appeared to be working normally !?

(The holding plate was frosted all over, so I think that the eutectic solution is intact.)

Presumably the problem was a mechanical blockage, rather than moisture? (Would it be possible that the moisture could be frozen out of the refrigerant in a non-critical place, only to cause problems again after allowing the system to thaw out?)

Fingers crossed that it will continue to work after it has been switched off and allowed to warm up!

Thanks for your help.


Richard

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Re: Frigomatic compressor fails to start
« Reply #14 on: August 31, 2013, 10:20:46 am »
“Very quickly there was frost on the holding plate, and it appeared to be working normally !? (The holding plate was frosted all over, so I think that the eutectic solution is intact.)”
ANSWER:

Earlier post with correct amperage in the beginning and then dropped to 3 amps and after running 6 hours confirms moisture in refrigerant and oil. I recommend super dehydration with a good vacuum pump for at least 4 hours while keeping complete system at near 100 degrees F.