AB frige Power Plate frosting only at the connection

[fero]

Hello,
I have a Hunter 40.5 1995 (purchased one year ago) equipped with Adler-Barbour frige and freezer with separate compressors and cold plates in separate boxes. I believe both are original with R-134, freezer works perfectly, the frige after working fine last winter seem to have problem. The only frost is on the connector to the cold plate (see pic) the compressor will run non-stop drawing 3.4 to 3.5 A, the cold plate will be around 35F and the connector 24 to 28F. Beer and vegies are cold but it looks to me something is blocking the gas in the connector and Also the compressor won’t stop as the thermostat sensor never sees cold enough. I wonder if someone experienced similar issue and also explanation for the localized frost buildup.
Many thanks

[Peter Mackay]

Hi Fero, from the photo it looks like you have lost refrigerant gas or have a refrigerant restriction. Suggest turning off the unit now until a technician can identify and rectify the problem, replace the filter/ dryer, evacuate and re-gas.

Cheers Pete

[Richard Kollmann]

Originally Posted by fero

Hello,
I have a Hunter 40.5 1995 (purchased one year ago) equipped with Adler-Barbour frige and freezer with separate compressors and cold plates in separate boxes. I believe both are original with R-134, freezer works perfectly, the frige after working fine last winter seem to have problem. The only frost is on the connector to the cold plate (see pic) the compressor will run non-stop drawing 3.4 to 3.5 A, the cold plate will be around 35F and the connector 24 to 28F. Beer and vegies are cold but it looks to me something is blocking the gas in the connector and Also the compressor won’t stop as the thermostat sensor never sees cold enough. I wonder if someone experienced similar issue and also explanation for the localized frost buildup.Attachment 207105
Many thanks

It does not look like you have a genuine Adler Barbour unit. The power plate evaporator looks like AB but the compressor would be a BD50. The amperage of 3.4 to 3.5 would also be too low for AB power plate unless someone removed compressor speed resistor located in thermostat wire about one inch from the mechanical thermostat control box

Chances are there is a refrigerant leak in one of the 4 AeroQuip line connectors. Each one of the line connectors has 4 Orings under tight compression. This type connector rarely leaks refrigerant like other quick connectors. The connector in picture is in suction side low pressure, when compressor is running more than ten minutes pressure in line will be somewhere between 4 and 10 psi.. The other connector in this same low pressure line is at the compressor/condensing unit. The other two connectors are on the high pressure line between plate and compressor. The high pressure side of the system is leak tested with compressor running and then pressure will be from 80 to 115 psi depending on amount of refrigerant lost and ambient temperatures.

When refrigerant slow leaks occur during the off season they are generally in the low pressure side of system because this is when the pressure in the low side of system is the highest with unit turned OFF. The method I recommend for finding small leaks is a 50/50% water and dish washing soap brushed on one suspected leak area at a time. Then using a one inch paint brush stab test area solution with brush tips till foam looks like your fathers shaving cream. It is important the test area extend up the line an inch or two in order to break down the surface tension between line and solution. You can hire a mechanic to use a electronic snifter but he won’t find as small a leak as you will with this method. Before moving to the next suspect area watch area tested for 5 minutes.

If a leak is found to be at an AeroQuip line connector the chances are it can be corrected by tightening slightly the loose area of the four piece connector very carefully. There are 4 separate pieces to this connector, at each end the copper line is soldered to end fitting. When connector is assembled as it is when leak testing there are 4 places where wrenches can be connected.
The procedure for tightening up on either end solder cap is to loosen the center connection a quarter turn using wrench on center large nut and holding its union next to it with another wrench.
With center joint loose enough to rotate either end cap can be tighten or its Oring replaced without twisting or breaking solder joint. WARNING if you do attempt to replace any of the Orings in this connector remove refrigerant first. These are not moving Oringe like other refrigerant connectors so I find slight torque of 1/8 turn tighter will correct these small leaks.

Power plates have copper evaporator coils inside not aluminum so there is no need to add a new filter dryer at this time. If you confirm later there is off and on moisture blocking of refrigerant flow add a new flare nut connected larger filter drier in a convenient spot in high pressure line between condensing unit and inlet to capillary tube control device.

[fero]

Thanks Pete,
I am inclined to think it to be more likely a restriction. I would love to hear from someone who had experienced the same thing and/or from a technician who encountered and corrected this issue. For now I run the frige during the day and shut it down during most of the night.

[Peter Mackay]

Originally Posted by fero

Thanks Pete,
I am inclined to think it to be more likely a restriction. I would love to hear from someone who had experienced the same thing and/or from a technician who encountered and corrected this issue. For now I run the frige during the day and shut it down during most of the night.

Hi Fero,
I have been a refrigeration tech for too long and serviced, repaired and built thousands of systems so I can help you while keeping it simple!

Suggest you add a small amount of refrigerant while the system is running and watch both your amp meter and the cold plate. If it is a gas leak (as I suspect) the amps will rise and there will be a larger area frosting after it runs on for a while.

That will be a good, simple starting point whereas you can determine what the problem is.
After that we can talk you through a remedy.

[fero]

Many thanks Richard and Peter,
I will start with testing as outlined by Richard.
Here is the picture of the compressor.
Just a note on consumption, I cannot confirm but it seams to me that frige amp consumption is about the same as it was last winter. The freezer needs around 4.5 amps.

[flyingfin]

Ice on the refrigerant line is usually indicative of low refrigerant pressure/volume, which results in the shift of gas/liquid/solid phase temperatures. With proper refrigerant pressure the line should be sweating wet, but not freezing over.

[Richard Kollmann]

Originally Posted by fero

Many thanks Richard and Peter,
I will start with testing as outlined by Richard.
Here is the picture of the compressor.
Just a note on consumption, I cannot confirm but it seams to me that frige amp consumption is about the same as it was last winter. The freezer needs around 4.5 amps.Attachment 207298

The new picture of condensing unit tells a much different story in that this is a 20 year old unit with a fixed speed BD3 Danfoss compressor. The BD3 low back pressure only compressor was sold to comply with the clean air act conversion from CFC refrigerant R12 to HCFC 134a.

The normal amperage on this unit with an ambient temperature 70 degrees F and above is 5 amps and slightly less once frost forms over much of power plates surface.

Your low reported operating amperage of 3.4 and frost only at plate fitting confirms loss of refrigerant. I recommend adding R134a labeled refrigerant with no datives very slowly until a stabilized 5 amps is maintained because it is a power plate evaporator. Using frost line superheat methods are a mistake.

This condensing unit picture does show the old AeroQuip large line connectors. The Orings in this connector only retain refrigerant before and during connection, once connected the final refrigerant seal is by a metal to metal seal. If this connector is found to be leaking use two wrenches to tighten it.

[fero]

Many thanks Richard, great input.

[fero]

I finally got a proper hose to fit the Schrader on the compressor (the automotive one, I got first, has a quick connect). Tested for leaks and didn’t find a leak. I added 3 successive shots (waiting about 20 minutes between each) of 4 to 5 seconds of R134a. Unfortunately I see no difference after couple of hours of continuous compressor running. The amps are, I believe around 5 to 5.3 (measured by a clamp ammeter actually was around 5 when I started. The previously reported 3.5 was by monitor shunt so I am not exactly sure which to believe, but tend towards clamp. To get to it I had to dismantle a setee.)
The hose I obtained didn’t have a gauge so I cannot confirm the pressure reading.
One thing I do not understand is that the frost is on the suction connector (as indicated by Richard). From reading various sources the frost is where is liquid refrigerant and where is no frost, only sweating, there is refrigerant in form of gas. The liquid comes from high pressure side, if I am not mistaken.

[Richard Kollmann]

It looks in the picture like you were correct in both cases the problem seams to be a restriction under the large frosted ball. Although I can not explain 3 amps to 5 by adding refrigerant if this is a restriction in liquid line unless system was low on refrigerant to start with and at the same time there is a restriction under the frosted area in picture. Remove frost ball carefully and you will probably find the cap tube and maybe a inlet screen partly restricted. If cap tube is plugged it would normally block all flow. send picture with frost removed. If there is a matching Aero equip connector under the frost there is a valve inside that could cause a restriction.

[fero]

Thanks Richard, will send picture tomorrow without the frost ball, I’ll stop the frige for few hours at night so it will melt by morning.

[fero]

It looks like my issue is a bit confusing. Yesterday evening, some 5 hours after adding refrigerant, I had a pleasant surprise, the cold plate was frosted, as seen on picture

Than at night the frige had long cycles on and off. In the morning, wile it was in off cycle, I could take a picture without frost on connector

I also did the soapy water test on inside connectors quickly without finding a leak.
The cycling continues, I will keep monitoring.

[Richard Kollmann]

Fero what is missing in the picture is the refrigerant flow control device most likely where the blockage is. Most likely this will be a long small capillary tube since the first picture does not show a refrigerant receiver required for a TXV.

The pictures now do not the point where refrigerant begins to vaporize and frost over line this would point out where restricted flow begins. Another picture is required in the area up stream, not shown in these pictures, few minutes after compressor is started.

[fero]

Richard, the frige is now quite full so I have limited access to investigate more closely, the good news is that it works well with probably 80 to 90% of cold plate surface frozen with long roughly 3 hour cycles and nicely cold box. The frost upstream of connector doesn’t go beyond some 2 nches. I was wondering where is the capillary. I think it is some 11/2 ft upstream under the box top in a spiral protection, not a very good picture attached. I have not seen any frost in that area. Going for 2 week sail will keep monitoring. Eventually I’d like to get low pressure reading.