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Author |
Date Posted |
Forum
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RE: Refreg freezing
Thermistor
The thermistor is a thermal resistor that changes resistance depending on its temperature. It clips onto the fins inside the refrigerator and communicates temperature changes to the appropriate circuit board by the change in its resistance. Normally when a thermistor goes bad it has a very high resistance and causes over cooling.
Dometic Thermistor To test the Dometic thermistor, disconnect it from the main (lower) circuit board and place the other end (sensor end) into a glass of ice water. After a few minutes you should be able to get a resistance reading of 7,000 to 10,000 ohms between the two terminals of the connector. If the resistance isn't close to those numbers, it is bad.
Norcold Thermistor On Norcold models up to, but not including the 900 series model, the thermistor should have a reading of around 40,000 ohms between the terminals of the connector when the sensor end is place into a glass of ice water
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Rob's
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08/28/10 06:27pm |
Tech Issues
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RE: Holding tank sensors
This Video might help Horst Miracle Probes Demonstration
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Rob's
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08/12/10 03:27pm |
Tech Issues
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RE: Cardinal Slideout Seal
There is lots of good info here
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Rob's
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08/11/10 06:13am |
Tech Issues
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RE: Troubleshooting gas fridge, heater, water heater
I would check to see if I had 12VDC to all appliances given the fact everything that doesn’t work requires an igniter that has 12VDC
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Rob's
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08/10/10 07:00pm |
Tech Issues
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RE: Dimming lights and refrigerator/freezer not working
If you have a Norcold Second Generation DC Operation
Check Here
If not I can post Dometic for you
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Rob's
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08/10/10 11:32am |
Tech Issues
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Horst Miracle Probes
Has anyone tried Horst Miracle Probes? and how do they work?
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Rob's
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08/08/10 06:06am |
Tech Issues
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RE: Refrigerator condenser bad?
It sounds like the cooling unit to me.
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Rob's
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08/06/10 03:31pm |
Tech Issues
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RE: Refrigerator problem
It sounds like the cooling unit to me.
Cooling Unit Diagnosis
The cooling unit, or coils, of an ammonia absorption refrigerator is the heart of the refrigerator--it does the actual cooling. Everything else on the refrigerator either supports the cooling unit, or is an accessory. No matter how simple or complicated the controls of the refrigerator are, all cooling units require the same three things to operate:
The unit has to be level
The unit has to have adequate ventilation
The unit has to have CORRECT heat
A fourth issue is raised if the cooling unit has recently been changed. The cooling unit has to have been properly installed into the refrigerator.
If the three above requirements are provided to the cooling unit, it should work and should work well. If it doesn't work well, then it is a bad cooling unit. It's really that simple. (Also, failure to meet the three requirements above when the refrigerator is in operation can cause permanent damage to the cooling unit.) Of course, don't overlook mitigating circumstances such as a main door that seals very poorly, which would cause a good cooling unit to look bad because of warm air continuously entering the box.
Also, if the cooling unit seems to work poorly only during warm weather, it's possible that one of the requirements above is in a border line state. In other words, the venting, for example, may be adequate for mild weather, but not adequate for warm weather. A cooling unit could also be border line, but it would be prudent to look elsewhere first.
Testing the cooling unit
First of all, if the cooling unit cools properly on one heat source (i.e. gas or electric) and not the other, then the cooling unit, with only a few exceptions, is good and the problem lies in the heat source that is not functioning properly.
Secondly, there are obvious signs of a bad cooling unit.
If you smell ammonia in or around the refrigerator, and you haven't recently used ammonia for cleaning, the cooling unit is bad. No further testing is necessary.
If sodium chromate is present on the outside of the cooling unit, the cooling unit is bad. Sodium chromate is a yellowish-greenish powder in solution inside the cooling unit. If sodium chromate is outside the cooling unit, the cooling unit has a hole in it.
If you hear a relatively loud gurgling or percolating sound when the refrigerator is in operation (being heated), it is a sign of a bad cooling unit. The key words here are "relatively loud". A good cooling unit percolates when in operation, and if you get close enough and listen carefully enough, you can hear it percolate. However, if you hear noise a few feet away, it is a sign that the cooling unit has lost pressure and is bad.
Testing the cooling unit is simply insuring that the three necessary requirements for the operation of a cooling unit (level, ventilation, correct heat) are met. Do whatever it takes to meet these requirements. If you suspect a venting problem, pull the refrigerator and set it on the floor. In fact, pulling the refrigerator and setting it on a level floor meets two of the requirements and leaves only one, correct heat, to worry about. Always test the refrigerator on the electric heat source, unless you are unable to because you have a gas only refrigerator. The reason for testing on the electric side is if the electric heat element gets hot, you can be better than 95% sure that you have correct heat, whereas even a poor gas flame will produce heat. To insure that the heat element is getting hot, you can touch the insulation pack (a rectangular or round sheet metal container filled with insulation located directly above the propane burner) to see if it is warm after about a half hour of operation. CAUTION: touch the pack lightly at first; it is possible under certain conditions for the pack to get super hot and burn you. If the insulation pack does not get warm, you have an electrical problem that needs to be corrected before continuing. If an electrical problem is not the electric heat element itself and/or you want to insure that some other electrical component (such as a thermostat) is not interrupting the heat element, you can hot wire the heat element for better testing conditions. The only weak link in this testing procedure is the less than 5% of the time that a working heat element is not producing the correct heat. See hot wiring for information on verifying the output of the heat element.
After you have provided the cooling unit with its three requirements, allow plenty of time for the cooling unit to function. You should see signs of cooling in the freezer after about two hours. Allow six to eight hours, or even over night, for an empty refrigerator to come down to temperature. The ammonia absorption style of refrigeration is slower than the compressor style in terms of initially bringing the refrigerator down to temperature. However, once the desired temperature is reached, there should be no problem in maintaining that temperature.
If you have done everything in this section up to this point and the cooling unit does not work or does not work well, the cooling unit is bad and will need to be rebuilt or replaced.
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Rob's
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08/02/10 06:30pm |
Tech Issues
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RE: Where is my converter - I've looked and looked
Follow your shore cord at 1 end it plugs into 110V and the other end it hard wires into your converter.
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Rob's
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08/02/10 10:30am |
Tech Issues
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RE: Dometic RM3663 Fridge Problems
Doug your right for the norm, but this model of Dometic has its board problems.
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Rob's
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08/01/10 07:05pm |
Tech Issues
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RE: Dometic RM3663 Fridge Problems
If you read your orignal post
"I have bypassed the control board and fed 12v to the solenoid and the flame burns continuously, though the fridge doesn't appear to get cold (though I've only done this for 30 min since if the flame were to go out, I could accumulate a dangerous amount of gas that could possibly explode if ignited)."
That tells me its the board.....It takes longer than 30 min to cool down an RV Refrigerator
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Rob's
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08/01/10 06:43pm |
Tech Issues
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RE: Domestic fridge install
Dometic® RV Refrigeration Replacement Chart
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Rob's
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08/01/10 12:32pm |
Tech Issues
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RE: Dometic RM3663 Fridge Problems
The cause is the circuit board. In fact, the circuit boards on these models are somewhat notorious for having a problem with the thermocouple circuit, resulting in an erratic check light problem. We have been replacing these boards with an after market board, the Dinosaur brand with very good success. It has a 3 year warranty and a special thermocouple circuit.
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Rob's
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08/01/10 12:17pm |
Tech Issues
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RE: Dometic Refrigerator Problem
Troubleshooting Basically, troubleshooting the main circuit board entails a knowledge of what should happen when and testing the input and output of the various connections on the board. If you suspect a communication problem between the main board and the eyebrow board, you can check the voltages at plug P1. If you suspect a cable problem between the two, you can check for voltages at P1 and at the eyebrow. Twelve volt goes to the eyebrow from P1, pin 4 and returns through pins 1 and 3 in P1 when the eyebrow switch is depressed to the "On" position. Knowing this and making corresponding tests at the eyebrow would test the cable between them. There is no test for the brown wire (pin 6, communication link). However, from experience, the eyebrow boards seldom fail. In a toss up, go for the lower, main board.
http://rvmobile.com/Tech/Trouble/Images/P1.gif height=100 width=99
Pin Number.....Wire Color..........Reading
1....................Green................12 volt +, when eyebrow switch on
2....................Open.................Open
3....................Black................12 volt +, when eyebrow switch on
4....................Orange or White..12 volt +
5....................Red..................12 volt -
6....................Brown................Communication link
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Rob's
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08/01/10 05:38am |
Tech Issues
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RE: making fridge colder
If fans or other measures are required to operate your RV refrigerator then most likely you have a failing cooling unit.
Cooling Unit Diagnosis
The cooling unit, or coils, of an ammonia absorption refrigerator is the heart of the refrigerator--it does the actual cooling. Everything else on the refrigerator either supports the cooling unit, or is an accessory. No matter how simple or complicated the controls of the refrigerator are, all cooling units require the same three things to operate:
• The unit has to be level
• The unit has to have adequate ventilation
• The unit has to have CORRECT heat
• A fourth issue is raised if the cooling unit has recently been changed. The cooling unit has to have been properly installed into the refrigerator.
If the three above requirements are provided to the cooling unit, it should work and should work well. If it doesn't work well, then it is a bad cooling unit. It's really that simple. (Also, failure to meet the three requirements above when the refrigerator is in operation can cause permanent damage to the cooling unit.) Of course, don't overlook mitigating circumstances such as a main door that seals very poorly, which would cause a good cooling unit to look bad because of warm air continuously entering the box.
Also, if the cooling unit seems to work poorly only during warm weather, it's possible that one of the requirements above is in a border line state. In other words, the venting, for example, may be adequate for mild weather, but not adequate for warm weather. A cooling unit could also be border line, but it would be prudent to look elsewhere first.
Testing the cooling unit
First of all, if the cooling unit cools properly on one heat source (i.e. gas or electric) and not the other, then the cooling unit, with only a few exceptions, is good and the problem lies in the heat source that is not functioning properly.
Secondly, there are obvious signs of a bad cooling unit.
• If you smell ammonia in or around the refrigerator, and you haven't recently used ammonia for cleaning, the cooling unit is bad. No further testing is necessary.
• If sodium chromate is present on the outside of the cooling unit, the cooling unit is bad. Sodium chromate is a yellowish-greenish powder in solution inside the cooling unit. If sodium chromate is outside the cooling unit, the cooling unit has a hole in it.
• If you hear a relatively loud gurgling or percolating sound when the refrigerator is in operation (being heated), it is a sign of a bad cooling unit. The key words here are "relatively loud". A good cooling unit percolates when in operation, and if you get close enough and listen carefully enough, you can hear it percolate. However, if you hear noise a few feet away, it is a sign that the cooling unit has lost pressure and is bad.
Testing the cooling unit is simply insuring that the three necessary requirements for the operation of a cooling unit (level, ventilation, correct heat) are met. Do whatever it takes to meet these requirements. If you suspect a venting problem, pull the refrigerator and set it on the floor. In fact, pulling the refrigerator and setting it on a level floor meets two of the requirements and leaves only one, correct heat, to worry about. Always test the refrigerator on the electric heat source, unless you are unable to because you have a gas only refrigerator. The reason for testing on the electric side is if the electric heat element gets hot, you can be better than 95% sure that you have correct heat, whereas even a poor gas flame will produce heat. To insure that the heat element is getting hot, you can touch the insulation pack (a rectangular or round sheet metal container filled with insulation located directly above the propane burner) to see if it is warm after about a half hour of operation. CAUTION: touch the pack lightly at first; it is possible under certain conditions for the pack to get super hot and burn you. If the insulation pack does not get warm, you have an electrical problem that needs to be corrected before continuing. If an electrical problem is not the electric heat element itself and/or you want to insure that some other electrical component (such as a thermostat) is not interrupting the heat element, you can hot wire the heat element for better testing conditions. The only weak link in this testing procedure is the less than 5% of the time that a working heat element is not producing the correct heat.
After you have provided the cooling unit with its three requirements, allow plenty of time for the cooling unit to function. You should see signs of cooling in the freezer after about two hours. Allow six to eight hours, or even over night, for an empty refrigerator to come down to temperature. The ammonia absorption style of refrigeration is slower than the compressor style in terms of initially bringing the refrigerator down to temperature. However, once the desired temperature is reached, there should be no problem in maintaining that temperature.
If you have done everything in this section up to this point and the cooling unit does not work or does not work well, the cooling unit is bad and will need to be rebuilt or replaced.
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Rob's
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07/30/10 08:14am |
Tech Issues
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RE: Norcold 682 Refrigerator
600 Series Power Supply Board
The Power Supply Board controls and activates all of the heat sources (AC, DC, and gas) of the refrigerator. It requires 12 volt power at all times for the refrigerator to work on any heat source. The Power Supply Board takes its settings from the eyebrow board and proceeds accordingly. It has the job of determining if AC is present, for example, and switching to gas if it's not. It provides voltage to the Ignition Control Module when gas is selected, and sends voltage directly to the 12 volt element and 120 volt element, when those heat sources are selected. The board shown below is for a 3 way model of the 600 series. The 2 way version would not use terminals J2 and J5, nor the 20 amp fuse.
One thing to note on this board is that the two blue wires leaving the board at the top complete a circuit through the On/Off Humidity switch. If you were to disconnect the two wires from their connectors on the wire harness going up the back of the refrigerator, and then connect the two wires together, you would by-pass the On/Off Humidity switch. If the switch was bad, this would allow the refrigerator to work. In fact, the single door models, like the 6053, don't have the On/Off Humidity switch and come from the factory with the two blue wires connected together.
http://rvmobile.com/Tech/Trouble/Images/682power.gif height=351 width=100
Wiring Code for Circuit Board
1 Interior light (-)
2 DC heat element (-)
3 12 volt (-) to battery
4 12 volt (+) to battery
5 DC heat element (+)
6 AC heat element
7 AC heat element
8 AC in neutral
9 AC in hot
Troubleshooting the Power Supply Board is a matter of testing what should come in and go out of the board. See the table above for information on that. Also, the fuses on the board should be tested. To access the fuses, the cover has to come off the board. Unplug the refrigerator, then disconnect all the wires going to terminals on the board. Pull the cover, then reconnect the wires for testing if necessary. This is also a good time to inspect the board for burned spots.
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Rob's
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07/28/10 12:34pm |
Tech Issues
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RE: Help
If the DSI board appears to be working correctly, but the flame is not lighting, be sure there is no air in the line and the manual gas valve at the back of the refrigerator is not in the off position. Remember there is a Trial for Ignition Period, after which the board will go into lock out. If propane has not reached the burner in this amount of time, the board will do its job and shut down. Sometimes, if air is present in the propane system, you will have to turn the refrigerator off (for about 10 seconds) and back on to recycle the board's sequence of operation. You may have to do this several times to purge the air from the propane line.
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Rob's
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07/28/10 08:04am |
Tech Issues
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RE: Dometic Refrigerator Problem
Dometic Electronic System (second generation)
The second generation Dometic electronic system is a completely revamped system that made some dramatic changes compared to the first generation system. The eyebrow circuit board is more than a set of glorified switches. It has its own micro processor and communicates with the lower circuit board. The thermostat is replaced with a thermistor. The lower circuit board (main) activates the appropriate heat sources and has a micro processor to communicate with the eyebrow board. There are also some important changes to the gas control system in the second generation system.
The graphic below represents a generic version of the second generation electronics system. You can find the specific model numbers of the refrigerators included in this generation below. Also, the wiring shown here is the later wiring. Later models came standard with this wiring, and many older models were updated to this wiring with a wire harness kit, usually installed with a new circuit board (after the original one failed). The older wiring can be seen here. The wiring difference is in the thermocouple and gas control parts.
http://rvmobile.com/Tech/Trouble/Images/2807tronics.gif height=400 width=203
As mentioned, the graphic above is generic, representing more than one model. Some are AES (Automatic Energy Selector), all can select between AC and gas (depending on the availability of AC) or set to gas only. Some are two way (gas and AC) and some are three way (gas, AC, and DC). Most have a temperature control, but some are pre-set and have no way to change the temperature setting. There are several variations of the eyebrow boards and main boards. Although Dometic uses numerous lower (main) circuit boards for the various models, at least one after-market manufacturer has managed to make one board that fits all models very successfully.
The main circuit board requires 12 volt to it for the refrigerator to operate on any heat source. In general, operation is started by the user pushing the power button "On" at the eyebrow. Depending on the eyebrow and the settings, a signal is sent to the lower (main) board telling it what mode to operate in. If "Auto" is selected, for example, the lower board knows to use AC (120 volt), if available, to heat the cooling unit. If AC is not available, the lower board knows to try to light the gas flame for the heat source. On models with a temperature control on the eyebrow, the setting initially starts at three. The user can adjust the setting up or down from there. A thermistor mounted inside the refrigerator on the fins in the lower box communicates the temperature to the lower (main) board by its varying resistance.
Standby Mode The main circuit board has two ways of coping with the failure of other system components:
1. If the eyebrow board becomes non-functional, the main board will go to Auto mode and select the best available heat source, with AC and Gas having priority. The temperature of the unit will be kept in the middle position. This depends a little on why the eyebrow board is non-functional. If the eyebrow were disconnected, for example, the refrigerator would not work.
2. If the temperature sensing system fails, the board would cause the refrigerator to cool continuously in the mode selected by the eyebrow. In other words, the refrigerator will not shut down as long as power is available. Usually the thermistor needs to be changed when this happens.
Models included in the Dometic second generation electronics: S1521, S1531, S1621, S1631, S1821, S1831, RM2607, RM2611, RM2612, RM2620, RM2652, RM2807, RM2811, RM2812, RM2820, RM2852, RM3607, RM3662, RM3663, RM3807, RM3862, RM3863, RM4872, RM4873, RM7030, RM7130, RM7732, RM7832, and NDR1062.
Rob
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Rob's
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07/22/10 09:43pm |
Tech Issues
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RE: Gray water tank
What make and model# is your board??
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Rob's
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07/21/10 07:40pm |
Tech Issues
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RE: Norcold N821 Poor Cooling
Given that you tested on 2 heat sources I would suspect the cooling unit. I would still bench test on electric before changing the cooling unit.
Cooling Unit Diagnosis
The cooling unit, or coils, of an ammonia absorption refrigerator is the heart of the refrigerator--it does the actual cooling. Everything else on the refrigerator either supports the cooling unit, or is an accessory. No matter how simple or complicated the controls of the refrigerator are, all cooling units require the same three things to operate:
The unit has to be level
The unit has to have adequate ventilation
The unit has to have CORRECT heat
If the three above requirements are provided to the cooling unit, it should work and should work well. If it doesn't work well, then it is a bad cooling unit. It's really that simple. (Also, failure to meet the three requirements above when the refrigerator is in operation can cause permanent damage to the cooling unit.) Of course, don't overlook mitigating circumstances such as a main door that seals very poorly, which would cause a good cooling unit to look bad because of warm air continuously entering the box.
Also, if the cooling unit seems to work poorly only during warm weather, it's possible that one of the requirements above is in a border line state. In other words, the venting, for example, may be adequate for mild weather, but not adequate for warm weather. A cooling unit could also be border line, but it would be prudent to look elsewhere first.
Testing the cooling unit
First of all, if the cooling unit cools properly on one heat source (i.e. gas or electric) and not the other, then the cooling unit, with only a few exceptions, is good and the problem lies in the heat source that is not functioning properly.
Secondly, there are obvious signs of a bad cooling unit.
If you smell ammonia in or around the refrigerator, and you haven't recently used ammonia for cleaning, the cooling unit is bad. No further testing is necessary.
If sodium chromate is present on the outside of the cooling unit, the cooling unit is bad. Sodium chromate is a yellowish-greenish powder in solution inside the cooling unit. If sodium chromate is outside the cooling unit, the cooling unit has a hole in it.
If you hear a relatively loud gurgling or percolating sound when the refrigerator is in operation (being heated), it is a sign of a bad cooling unit. The key words here are "relatively loud". A good cooling unit percolates when in operation, and if you get close enough and listen carefully enough, you can hear it percolate. However, if you hear noise a few feet away, it is a sign that the cooling unit has lost pressure and is bad.
Testing the cooling unit is simply insuring that the three necessary requirements for the operation of a cooling unit (level, ventilation, correct heat) are met. Do whatever it takes to meet these requirements. If you suspect a venting problem, pull the refrigerator and set it on the floor. In fact, pulling the refrigerator and setting it on a level floor meets two of the requirements and leaves only one, correct heat, to worry about. Always test the refrigerator on the electric heat source, unless you are unable to because you have a gas only refrigerator. The reason for testing on the electric side is if the electric heat element gets hot, you can be better than 95% sure that you have correct heat, whereas even a poor gas flame will produce heat. To insure that the heat element is getting hot, you can touch the insulation pack (a rectangular or round sheet metal container filled with insulation located directly above the propane burner) to see if it is warm after about a half hour of operation. CAUTION: touch the pack lightly at first; it is possible under certain conditions for the pack to get super hot and burn you. If the insulation pack does not get warm, you have an electrical problem that needs to be corrected before continuing. If an electrical problem is not the electric heat element itself and/or you want to insure that some other electrical component (such as a thermostat) is not interrupting the heat element, you can hot wire the heat element for better testing conditions. The only weak link in this testing procedure is the less than 5% of the time that a working heat element is not producing the correct heat.
After you have provided the cooling unit with its three requirements, allow plenty of time for the cooling unit to function. You should see signs of cooling in the freezer after about two hours. Allow six to eight hours, or even over night, for an empty refrigerator to come down to temperature. The ammonia absorption style of refrigeration is slower than the compressor style in terms of initially bringing the refrigerator down to temperature. However, once the desired temperature is reached, there should be no problem in maintaining that temperature.
If you have done everything in this section up to this point and the cooling unit does not work or does not work well, the cooling unit is bad and will need to be rebuilt or replaced.
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Rob's
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07/20/10 06:00am |
Tech Issues
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