Forum
Too Much
Refrigerant
- Too Much Refrigerant in Small Capillary tube System
- Twelve volt units with Too much refrigerants and finding leaks
- Improperly serviced
- Servicing BD (Variable speed compressor)Too much refrigerant?
- Too much Refrigerant Now what do I Do?
- Servicing BD35 Another overcharged system
- Return Line Icing Too Much Refrigerant
- Too Much Refrigerant in Small Capillary tube System
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With the complete system
warm and turned off and the refrigerant overcharged there will
be more than 50 psi in the complete system.
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Apply the liquid mixture to
one location at a time. Use brush tips to stab the fitting. This
will break the surface tension. Continue stabbing on the mixture
until a foam is generated that looks like shaving cream.
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Watch that fitting for two
to three minutes before moving to the next fitting.
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With the compressor stopped
for at least 5 minutes, depress the servicing port, valve core
located at the top of the compressor, NOT at the line service
valves, for 3 seconds allowing the refrigerant to escape, then,
replace the sealing cap over the valve.
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Start the compressor, if the
amperage drops quickly below 8 amps, the compressor should run.
I have an Adler Barbour with a BD50 compressor on one of my test
stand and AB’s small bin evaporator at a controlled temperature
of 80 + 1˚F Start amperage after one minute is 6.5 amps. If your
system’s evaporator is colder than 80˚, amperage may be less. If
warmer than 80˚ the amperage may be slightly higher than 6.5
Amps.
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If the compressor stops
again because thr amperage is above 7.5 amps or you receive a 3
flash LED signal, repeat item 1. and 2, but this time release
the gas for only 2 seconds. The compressor must be turned off
for 5 minutes each time before releasing refrigerant and the
leak proof cap must be installed tight when NOT releasing gas.
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Repeat steps until the
compressor runs without stopping even if amperage is still above
6.5 amps. Final fine tuning will depend on visual frost
formation on the evaporator’s surface area and no frost on the
return line and no amperage. as it will decrease as the plate
temperature drops. There also may be an error in your amperage
reading.
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With unit turned off, bleed
off refrigerant for one second then wait five minutes and turn
on power.
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Run unit long enough to form
frost line and repeat the above process until frost line is
retracted to within a few inches of evaporator. For pressures to
equalize it is important to wait 5 minutes each time before
starting compressor.
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Once overload condition is
removed let unit run for one hour. Now check frost line on
evaporator. With the correct refrigerant charge, the complete
evaporator will have a thin layer of frost on 100% of its
surface but no frost on line returning toward compressor.
Common complaints,
refrigeration technician added too much refrigerant. Poor performance and frost
on refrigerant line returning to compressor
Things to remember if
refrigerant level is in question:
• Do not connect gauges needlessly always perform non destructive testing first.
• Purge
gauge set.
• The box
and complete system must be warm when adjusting refrigerant charge.
• Adjusting
refrigerant charge when evaporator is cold may not produce good efficiency.
• Don’t
connect refrigerant gauges when compressor is running, it is a good way to
contaminate refrigerant
Action recommended:
1.
Stop compressor and remove a very, very small amount of refrigerant. Run system
15 minutes, then check frost line it should not extend on un-insulated line more
than a few inches outside refrigerated box in cold weather, in warm weather only
condensation should be present outside the box. If there is still too much frost
stop compressor and repeat process. When operating properly there must be a
layer of ice forming over 90% of evaporator’s surface. If too much refrigerant
is removed there will be an area of the evaporator without frost.
2.
Once the system is operating OK set the thermostat to full cold for at least 12
hours. If at the end of this test run evaporator has lost its frost and
evaporator is cold with only condensation on it there is moisture in the
refrigerant.
3.
If letting out refrigerant did not solve the performance problem or system
freezes up due to moisture, a refrigeration vacuum pump will be required to
remove air, moisture or incorrect gases.
I don’t like to connect gauges to a system until I have proven that the
refrigerant is the problem. Make sure there is adequate airflow through the
condenser. If your evaporator is a thin aluminum plate and not an Adler Barbour
Power Plate the frost line will indicate if the refrigerant charge is correct.
When there is sufficient refrigerant there will be frost covering 90% of the
evaporator’s surface and no bare spots. One half an ounce too much refrigerant
on a small cap tube system could double the daily amp-hrs consumed, see chart on
page 56 in 12/24 volt book.
You will
find answers to your questions on connecting 134a refrigerant to standard gauge
set on page 57 under Pre-servicing Information. Acme Fitting also pictured page
57 on compressor suction service port.
Adler Barbour’s new super cold machine with BD 50 compressor has the same
components as the cold machine except the super unit has a small supplemental
water condenser on liquid pressure line. Servicing a DB50 with a capillary tube
expansion device is the same as servicing your old BD compressor except with
134a there is a small pressure difference. If you do need to add refrigerant
follow the steps listed on page 58 and 59 to the letter and you will end up with
an efficient system.
2.
Twelve volt units with
Too much refrigerants and finding leaks
A frequent problem that
occurs when servicing a 12/24 volt small refrigeration unit is that you or a
service tech has added too much refrigerant to the system. While the unit is
overcharged, check to see if there is frost on the return line and a 3 LED
signal. This will confirm that too much refrigerant has been added. The first
thing that you must do is to check for any leaks that might have been overlooked
prior to servicing.
First
check for any leaks: The areas to
check for leaks on AB Cold Machines are: mechanical line connections, the three
refrigerant service connection leak proof caps and line connections at the power
plate, if you have one, instead of a standard aluminum evaporator.
By using a one inch paint
brush and a 50/50 mixture of liquid soap and water you will be able to find
leaks as small as a ½ ounce per six months if you follow these instructions:
If one of the serving caps
or line connectors are leaking, use two wrenches to tighten but never tighten
any tighter than what it takes to stop the leak. Some of the power plates have O
rings as seals so in order to stop a leak there, it may be necessary to remove
the refrigerant and replace the O ring seal.
To correct an overload -
indicated by frost on the return line and confirmed by three LED flashes, do the
following:
After two or more hours
running time the evaporator’s surface area should be covered 95 to 100% covered
with a thin layer of frost with no frost on the return line outside of the
refrigerated area on the line towards compressor.
After 40 years in the tool
and die business, I have switched professions to Marine canvas and Marine
Refrigeration. Just today I was asked to charge an older AB system and found the
compressor much warmer than I liked. I found the low side at 16 psi and
compressor amperage at 7.6 equalized pressure on this system was 40 psi
I bled the system down to
7-8 psi and normal ranges prevailed.
My question may be more
ethical than technical but this system was apparently charged by someone who
didn't know where they were heading. Would it be prudent to advise the customer
to pay for a recovery and deep vacuum with recharge to eliminate the possibility
of air from lines they may not have bled properly . I don't know how many times
they may have opened the system.
Answer: I hear of at
least two systems a week that have been serviced incorrectly. The first thing to
determine is why it was necessary in the first place to tamper with refrigerant
level. In many cases poor or no cooling performance relates an electrical
problem with boat wiring or Danfoss compressor and not refrigerant volume. Once
the decision is made to connect gauges to one of these small systems the door is
open to major contamination problems. If refrigerant was truly needed then there
is a leak and it needs to be found before evacuating and re-servicing. In the
last twenty years I never charged for a service call to add refrigerant to one
of these systems if I could not confirm and repair the leak.
4. Servicing BD (Variable
speed compressor)Too much refrigerant ?
This older
unit is destined for service. It cools my 8cft freezer box, and I have installed
a new CU-200 and vd -162 in the refrigerator portion- which is approximately
12-14 cuft with 4" insulation. For the fridge, I bought the evaporator new, but
the compressor deck was 1 year old and had been used for that period. I removed
the old couplings and soldered on new, also soldered on a new filter/dryer and
then vacuumed the unit and charged it to the max it would hold with 134a. I then
vacuumed it again and recharged to the max it would accept (65 psi) with 134a
again. At that point I connected the unit to the evaporator per the
instructions.
Right now, at the
coldest thermostat setting, (traditional non-digital thermostat) the unit cycles
on for 5 minutes and off for 12. This keeps the box at or just under 40˚. I
would prefer 35˚ or less. I wonder if I need to change the amount of refrigerant
or adjust the thermostat. The compressor deck ambient temp is around 85˚ (inside
the cabinet where it is installed).The total charge was around 58 psi in the
compressor deck before I connected the evaporator. Please let me know the ideal
run/rest times for the compressor and how much charge pressure should be in the
system.
Answer:
5. Too much Refrigerant
Now what do I Do?
The unit I
have is a cu-200 from 2006. It is a BD50. The thermostat capillary tube is
correctly installed and the refrigerant tube frosts back about 5 feet. When it
exits the box, there is no frost line, only inside the box.
I am also quite
positive I have overcharged the system, but I would like to know the correct
operating pressures on suction and return, or just system pressure to get a
ballpark figure on how much refrigerant this system needs. When the thermostat
capillary tube was not installed on the evaporator the unit ran continuously
with no faults indicated on the control unit led.
Answer:
Five ft of frost on the
return line would indicate too much refrigerant on that manufacturer’s
condensing unit and evaporator. Refrigerant volume is very critical on a
refrigerator that incorporates a capillary tube expansion device and there is
very little room for error if energy efficiency is important. To pre-charge your
system, to a specific volume by weight is not possible for you to do. The only
way to service your unit is by suction pressure, frost line or amperage.
Assuming there are no restrictions in any connections you made in tubing
(soldering small tubes together can cause blockage}, and refrigerant is 134a.
Here is what to do to relieve the over-charged condition:
6. Servicing BD35 Another
overcharged system
First, thanks for all
your help and such a great web site. Both your books have been a great help.
I am trying to charge a
new bd35 with an old box evaporator and oversized condenser per my last post.
Ambient temperature is 80, pre-start pressure is 84psi, low motor speed.
After three minutes, I
reach a low side pressure of 8, high side 110. Within 5 minutes, the low
pressure moves back up to 15psi and stays there.
I get frost over the
entire evaporator with an outside box temperature where the lines go in of 14
degrees.
Your book and prior
posts suggest that I should get to 6-8 psi and then after the box cools, the
pressure should continue to go down. My pressure drops to 8 then back to 15.
Any suggestions,
Thanks again for all of
the valuable help.
Answer:
The correct
procedure was to start up a warm system and let it run 10
minutes then adjust 134a refrigerant suction pressure to 6 to 8
psi in the next five minutes. From then on pressure will drop as
the evaporator cools and no more adjustments are made.
At 15
psi the evaporator will not get cold enough and power
consumption will be twice normal. If you warm the system up,
then reduce the suction pressure to 6-8, in a time window
between 10 to 15 minutes the refrigerant level will be correct.
I would
expect at 80˚ ambient and 2000 rpm the amp draw of a BD35 will
be less than 3 amps.
___
7.
Return Line Icing
Too Much Refrigerant
Why do I have frost on my
refrigerant line all the way back to compressor?
Answer: Adler Barbour and other
similar ice box conversion units supply a three foot piece of
insulated tubing to use on the lines just outside the box. In
moderate temperatures and humidity three feet of insulation
should be enough to prevent moisture on the lines outside the
box. There is one condition that will produce frosting on the
return line and extend the compressor running time, and that is
too much refrigerant in the system. The factory refrigerant
charge will not cause this condition but if the system was field
serviced with refrigerant that could cause the problem you
describe.