Author Topic: Dansfoss db35 cycle constantly  (Read 8145 times)

suttonski

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Dansfoss db35 cycle constantly
« on: May 27, 2013, 08:15:59 pm »
Hi,
 
I have a problem with my Adler Barbourcu-100 and would like to fix it myself to become autonomous because I am planning a very long trip next year.
 
Unit:
Adler Barbour CU-100 (air cooled) (120 g of R134a)
Evaporator 12 X 40
Mechanical Thermostat
Freezer: 18.5 X 16 X 24 ⍊
Refrig.: 15 X 24 X 21
No LED flashing
 
Condenser is clean.
Voltage 13.7V DC
Thermostat is jump
Spill over fan to refrigerator close.
Insured thermostat was not touching evaporator.
I connected my temperature sensor to the Evap at start and read temperature.
 
Did a vacuum twice for around 10 hours each time and it is still not working properly.
 
During the weekend I started with the unit working and drawing about 3.4 Amps, the freezer was at +1C, the temperature started to drop and after 10 minutes it was at -20.4C.  It stayed there for about 1 minute then it started to go back up to -4.4 then it went down to -18.7C. When back to -2.4 and stayed there for a while before going down to -18.4 and again very quickly went back to -1.8.
 
I can not get the Evap to stay at about the same temperature.  It fluctuates constantly and it seems that the compressor stops working although there is a jumper between terminals C and T
 
Why would the compressor cycle on and off like that.
 
I guy came over yesterday and added more R134a to a point that after 45 minutes the low side vacuum was still reading 10 PSIG.  We stopped the unit and restarted is 2 minutes later and I noticed that the LED was flashing 3 times, meaning the  pressure was too high which I thought would happen because there was too much gas in the unit.  So we removed some gas.

I removed the unit completely and he took it to his shop to replace the dryer. 

Last Friday evening I re-installed the unit an on Saturday I evacuate the system with my vacuum pump  for 16 hours non-stop.
Saturday evening I stated recharging the system slowly.


Initially there the temperature dropped very slowly:
3.5C
1.0C
-0.4C
-1.2C
-3.2C at 9:30
-4.7C at 9:33
-5.8C at 9:37
-6.2C at 9:40
-7.5C at 9:42
-6.7C at 10:00 (Evap temp rose instead of keeping going down)
-9.8C at 10:25
-10.9C at 10:50 (at that point the temperature stayed there for a short period before going back up)
0.0C at 11:15
-9.3C at ?
+0.6C at ?
-6.2C at ?
-1.2C at ?
-10.8C at ?
+0.9C at ?
-10.1C at 11:35
+0.8C at 11:40
-9.8C at 11:42
+0.6C at 11:44
-11.3C at 11:57
+1.9C at 00:03
-10.8C at 00:09
+2.7C at 00:16
-9.5C at 00:22
+1.1C at 00:28
-10.6C at 00:37
+0.1C at 00:45

Time to go to bed! Please note that I added R134a very slowly and not every time the unit was cycling up and down.

-16.1C at 6:26AM
-1.8C at 6:30 AM
-3.0C at &:05 AM
-16.6C at 9:40AM
-5.0C at 9:46AM
-3.2C at 9:51 AM
-14.8C at 8:58AM
-0.9C at 10:09AM
-12.4C at 10:13AM
+0.1C at 10:30AM
 
I think that at this time I reached a point where adding gas made things worse and the evap temp would not drop past -4.0C.
I stopped the unit for 30 minutes and removed some gas.  I restarted the unit and the same pattern repeated itself, up and down with a low around -9.0C

I had problem with the unit 4 years ago and by doing a good vacuum and adding gas slowly I got the evap to -24C and staying at that temp.  Today, I can not get the a stable evap temp, it goes up and down like a yoyo! IMG4 shows you the evap installed on my Beneteau 361 year 2000.

The problem is that the compressor is not running all the time.  I noticed that when the temperature is going down the unit is pulling around 3.5Amps then suddenly, the temperature starts to go up and the unit is only drawing around 2.2Amps.  I think that this is way off since in the past when the unit was working properly it would start at around 9Amps and drop to an operating current staying around 5 to 5.5Amps! 

Two years ago, in spring,  when my boat was out of the water before being re-launch, there was a lightning strike on the marina electrical circuit and I was connected to that circuit.  Two Raymarine instrument were damaged and I also had to replace the cooling fan on my Adler-Barbour unit.  The unit worked well until last August were I started having cooling problems. 

Could the Control Module be at fault, causing the compressor to stop and start?

Could the evap be blocked?  I can hear gurgling in the evap.   

I hope you can help me out with the steps needed to get my unit working properly.  I can not go very far with a unit working continuously!  It will drain my batteries in no time.
 
Where can I find an evap of 11in by 40 in?

Sorry for the long mesage and thanks in advance for the help.

Richard

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Re: Dansfoss db35 cycle constantly
« Reply #1 on: May 27, 2013, 09:04:00 pm »

There are two possibilities incorrect refrigerant charge or a problem inside AB's stainless steel box.  To eliminate the circuits inside this box that have created problems for many others I need you to put a jumper wire around the stainless box positive power circuit.  But first make sure the boats power fuse or circuit breaker for this refrigerator is no larger than 15 amps because you will be bypassing 15 amp fuse protection inside stainless box.

With refrigerator power off connect jumper to large plus terminal on stainless box along with existing boat power wire. Now connect other end of jumper to large plus on Danfoss control module along with present wire there. This means there are two wires on each large plus terminal sending boat power to both boxes bypassing circuit board inside stainless box. Now power up unit and see if problem is solved. With other jumper between C and T evaporator temperature should be stable and keep getting colder as long as compressor runs.



suttonski

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Re: Dansfoss db35 cycle constantly
« Reply #2 on: May 28, 2013, 12:04:03 am »
Richard, thank you very much for the testing procedure. I will go to my sailboat this week and try this.  Just to make sure, when you are referring to the stainless box you are referring to the box shown in the attached picture(IMG5).  What is the purpose of that stainless box? I was looking at Frigoboat and noticed that they don't have that box. 

On the stainless box we have 12V DC power supply from the breaker panel and on the same connectors power for the spill over fan from the freezer to the refrigerator.  We also have power for the condenser cooling fan.  Couldn't all these connections be done on the Danfoss Controller Module?

Last fall I bought a Merlin speed controller that I wanted to install on the Danfoss but with my current problem it is still in the bag.

Please note that the R134a that I am using comes from Autozone and contains leak sealer.  Could that be a problem?  Can I easily buy R134a without leak sealer? IMG2 shows were I have attached my temperature sensor.
Thanks again for the support.
Georges
 

Richard

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Re: Dansfoss db35 cycle constantly
« Reply #3 on: May 28, 2013, 05:50:20 pm »

Yes your picture is of stainless box that you are to bypass power circuit inside. Purpose of box on CU`100 models was to incorporate a relay inside to handle current of additional fans and mount troubleshooting LED. It also helps to sell another troublesome electronic gadget thermostat.

If your problem is inside stainless box its limited to power wire solder connections and all other functions will work as they will be fed by both ends of bypass wire.

Refrigerant flow where you have taped thermometer at times is not stable so move probe off and away from refrigerant tube.

134a with leak sealer was a mistake, there are two types one that seals rubber seal by increasing there size. The other seals both rubber and leaks in metal. Once AB’s new connectors are tight refrigerant is sealed in by metal to metal seals. There are no rubber seals in their thin plate evaporator systems. There is a chance that the additional oil and leak sealant you added will plug refrigerant flow. I know on way to correct this situation if it is truly going to cause difficulties.

Troubleshooting is the process of elimination, if bypassing box does not produce results refrigerant volume and flow are in question. Work done by refrigerant can be measured by amperage and low side pressure. If you can measure one or both every ten minutes during a test refrigerant flow performance can be measured. One of my test stands has the same setup as yours BD50 compressor and thin plate evaporator. It would help if we new the size of compressor speed resistor in thermostat wire. If the paper decal P/N is still on thermostat the last numbers are resistor size 1500 would indicate max speed 3500 rpm.
I will also need approximate ambient temperature inside boat where compressor is located.


suttonski

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Re: Dansfoss db35 cycle constantly
« Reply #4 on: May 28, 2013, 06:16:32 pm »
Hi Richard,  Thank you very much for helping me on this.  I will proceed with the power supply to the compressor and stainless steel box  as per your recommendation.  Would it be better to do another vacuum again for 12 to 16 hours to get ride of the R134a with sealer and replace with regular R134a before or should go ahead with the test and see what's going to happen.

Richard, are you the author of 12 & 24 Volt refrigeration Book?  Last night I wanted to buy the book and  it did not work out because I wanted it shipped to my marina in Plattsburgh, NY, and my billing address is in Canada.

Thanks again for the support.
Georges

Richard

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Re: Dansfoss db35 cycle constantly
« Reply #5 on: May 29, 2013, 07:13:25 am »
All the leak sealers I tested the sealant is in the oil and now it is in compressor oil and can not be removed by vacuuming.

I will email you about my 12/24 volt book.



























































suttonski

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Re: Dansfoss db35 cycle constantly
« Reply #6 on: June 03, 2013, 11:58:51 pm »
Hi Richard,
I did exactly what you said and I got the compressor to work continuously but I was not sure if the system was clean because I tried so many things before.  So I decided to start fresh and did a vacuum for 5 hours. I then started to fill in the system slowly (R134a without any leaks sealer) and use my clamp meter to monitor the amps used by the system and an electronic balance to measure the amount of R134a injected in the ssytem.  The voltage was always around 13.8V but the amps never got over 3.02 when I checked the amps with my Mastervolt system shunt the reading was about 3.3amps.  Last weekend was very hot and humid and I started with a freezer 27C!

I have prepared an excel document with my observations showing the evap temp, time, amps, R134a weigh and PSI. I also decided to read the evap temp, at multiple locations,  using a laser temp reader.  Maybe it would better if I e-mailed these information with drawings showing what I got.  I use kitchen electronic balance to measure the amount of R134a injected in the system, but I am not sure of the accuracy of this device. 

Four years ago I had problem with this system and I finally got the evap to drop to about -22 Celsius (vacuum around -2" Hg) but the Adler-Barbour Technical Manual that I was given by Dometic indicates that I should have the following temp after 160 minutes:
-16/-14 F at evap start  (-26/-25 C)
-12/-9 F at evap midway  (-24/-22 C)
-13/-11 at evap end (-25/-24)
with a PSI of -2 to -3 ``Hg
with no line frost outside the box.
I am not sure which way is the start and which is the end because there is only one tube coming into the box.
I can send you the Technical Manual that I have.

The minimum I got was -18.8C and the vacuum was always around 5 or 6.

I had to come back from the marina Sunday afternoon but I left the unit on with very ventilation.  I will go back maybe Wednesday night and would appreciate your input on the best way to get the evap temp down.

I bought your book (sent you a money order last Friday) and I am looking forward to some very interesting reading.
I want to fix this for optimum performance and be autonomous  because I am planning a long trip to the Bahamas, Carribean, and probably Baja California.
Thank you very much for your patience and support.
Georges





Richard

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Re: Dansfoss db35 cycle constantly
« Reply #7 on: June 04, 2013, 03:12:35 pm »
I received your Email and looked at your figures as you try to set evaporator superheat. Adler Barbour’s Textbook super heat setting for professionals is not what I recommend. The method I use is in my book and web site is also from Adler some 20 years ago. The pages are not numbered in AB Manual but scan farther till you get to 134a Service Data Sheet.

To use this chart: Pick your evaporator and adjust refrigerant volume to suction pressure in a time window 10 to 20 minutes after starting with a warm box.  Then do not tamper with refrigerant again. I do not know what ambient temperature is where you are now but warmer climates will raise pressures and cooler temps will lower them. As long as evaporator frost covers 85% or more of evaporator and no frost is on line returning toward compressor refrigerant level is good. If the present air temp is 70 degree F and boat is moved to a much colder climate frost on a two ft section of line outside box is going to be normal.

suttonski

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Re: Dansfoss db35 cycle constantly
« Reply #8 on: June 04, 2013, 06:39:42 pm »
Hi,
Thank you very much for the info.  My sailboat is currently on Lake Champlain near Plattsburgh, NY and last weekend when I tried to adjust the AB system the outside temperature was in the lower 80s with a lot of humidity.  I am looking forward to reading your book.  How come the compressor and fan dont draw more than 3.6amps?

Thanks
Georges 

Richard

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Re: Dansfoss db35 cycle constantly
« Reply #9 on: June 05, 2013, 10:57:23 am »
The BD50 is standard on AB CU100 systems if yours has a BD35 compressor 2.4 amps at minimum speed is normal. At max speed BD35 will draw 4.4 amps. These figures vary depending on many other conditions ambient air, condenser and evaporator temperature, superheat setting and cap tube size.

suttonski

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Re: Dansfoss db35 cycle constantly
« Reply #10 on: June 10, 2013, 12:49:12 pm »
Hi Richard, I let my compressor on last week and when I got back to my sailboat last Friday the freezer was at -20C and the evap was around -22C but only 75% had frost.  The last section had no frost at all. The gauges were connected with the small gas tank and the vacuum was about -10.  I thought that I was missing a little bit of gas but my wife prefered that I did not touch it.  Experience is the sum of our mistakes.

1) I disconnected the hose to the compressor without stopping the unit first and waiting for a positive pressure.
2) Saturday morning I decided to add a little bit of gas and made sure that the hose was full before connecting it, but again, because of lack of experience I connected the "/$% hose without stopping the unit.
Off course this just blew the system,the temperature started rising and I was back to square one.
3) I stopped the unit and waited for 30 minutes
4) I connected my vacuum pump and ran it for 4 hours.
5) Insured gas was in the hose
5) Started the compressor
6) A dded gas slowly
7) Sunday the system was again reading -20C and the evap was frosted completely.
8) I stopped the unit and waited 30 minutes before disconnecting the hose
9) I noticed that the cap that goes on the vacuum port did not have any o-ring so I put one in.
10) I reconnected the thermostat, and increased the jumper wire size (the one you suggested to bypass the stainless box)
11) Started the unit
12) 5 hours later the evap was only at -2 or -3.  The unit was not performing well at all!
13) Stopped the unit and waited to check the pressure, it was always negative.
14) I thought I was missing some gas so I started the unit and added gas but the pressure would not go up at all. (BIG MISTAKE)
15) I noticed that the compressor was a lot noisier than normal and I thought there was now too much gas in the system.
16) I stopped the system. Pressure was always negative.
17 ) I don't know why but I decided to heat the evap with an air dryer and bingo, the pressure went sky high.

I think that I have some humidity in the system and that it freeze blocking the flow to the evap( my interpretation)
I will have to start over again but I would like to find out how long do I need to run the vacuum pump to get ride of everything?  If I heat the evap with an air dryer will this help remove the humidity-air from the system?

I noticed that when I screw in completly the adapter to connect to the quick connect from my blue hose that there is gas coming out of the system.  If I back off the adapter by 1/4 turn there is no gas coming out but this is certainly not good.

I haven't receive your book yet but I will be going back to the marina probably tomorrow evening to do the vacuum.  I want to do everything right this time.   Can I use the gauges and connect the vacuum hose to it?  In the past I was connecting directly a hose (red) to the vacuum pump and that was it.  Can I see something if I use the gauges for the vacuum?  How can I add gas the first time?  If I leave the blue valve open the pressure will become equal but won't I have too much gas in the system?  I only need 120gr apparently.

I think that after this I will be much more knowledgeable and won't ever make the same mistakes.  I will be ready for my trip South.

Thank you so much for your understanding and support.  No easy to find someone in this field.

Kind Regards,
Georges
« Last Edit: June 10, 2013, 12:59:24 pm by suttonski »

Richard

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Re: Dansfoss db35 cycle constantly
« Reply #11 on: June 10, 2013, 07:04:24 pm »
I must also have to start over an evaporator temp of -20C (-4 F) may be all you will ever get. What evaporator temperature are you looking for?

The mixed up information you are providing is of no value to you are me if you keep playing with refrigerant level. If there was ice blockage frost on plate will disappear and suction pressure would be in a very deep vacuum.

Follow my directions this time. Let complete system warm up to ambient temperatures this includes inside box and record temperature.
COMPRESSOR MUST REMAIN OFF Now remove refrigerant and add refrigerant till low press stays stable at 60 psi, if necessary to raise pressure set refrigerant bottle in warm water Not Hot Water. COMPRESSOR IS STILL OFF. Remove gauge set and install sealing caps on service ports.  Now turn compressor on for several hours and then record where you see frost and where you do not see frost. Describe in detail. Post findings. Turn unit off for many hours. When you come back to the boat run compressor again till frost areas are equal to previous test. and again report findings. In Detail. DO NOT TOUCH REFRIGERANT LEVEL OR CONNECT GAUGES. Tell I tell you to.

suttonski

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Re: Dansfoss db35 cycle constantly
« Reply #12 on: June 10, 2013, 07:45:16 pm »
Hi Richard, Thank you very much for the procedure, I will follow it precisely.  I was not looking for a lower temperature I was just going with the indication that the evaporator should be 85% frosted.

I will start your procedure tomorrow evening.  You indicate that I have to remove refrigerant and then add refrigerant till low pressure is stable at 60PSI.   I assume you want me to run my vacuum pump to remove everything that is in the system.  If yes, how long do you suggest I ran my vacuum pump? I can do this for 14 hours maybe 24 if you think that it is necessary for a very good vacuum.
Thanks
Georges

Richard

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Re: Dansfoss db35 cycle constantly
« Reply #13 on: June 10, 2013, 08:04:46 pm »
If you start this test with a warm box  and system is say 21 to 26 degree C (70 to 80 F) 60 psi static will be close but do not worry about temperature just record its warm timperature. You can not solve a problem until a base line is established.

If you think air got into system then remove refrigerant and vacuum for 15 minutes.

suttonski

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Re: Dansfoss db35 cycle constantly
« Reply #14 on: June 13, 2013, 12:23:57 pm »
Hi Richard,  I went to my sailboat Tuesday and wanted to make sure that I started with a clean system so I did a vacuum for 12 hours. 
In the morning, the freezer was at +22C and the evap was also at +22C.
I did exactly what you said:
My small R134a tank was connected to the yellow hose and I opened the blue hose to get air out and I made sure that R134a gas was coming out.
I connected to blue hose to the low pressure port.
I opened the blue knob and I let the pressure stabilize.
In a short time the pressure was stable at 55PSI.
I put the R134a can in warm water and the pressure increased to 60PSI.
I closed everything and disconnected the hose.
I put the cap on the low pressure port
I started the compressor and waited 2 hours.
After 2 hours the freezer was still at +22C and the evap was at the same temperature.
Since I had to come back to work, I stopped the system and I left it that way, did not do anything else.

According to the tag attached to my AB system the unit (compressor and evap) were loaded with 120gr of R134a at the plant.  A stable pressure at 60PSI does not mean that I have the right amount of gas in the system right?
Thanks
Georges