When you are having trouble with your Dometic AC control board, the problem may lie with the control board or it may lie with some other part. It can be expensive and confusing to try and fix this issue yourself.
If the control board is bad, then your only repair would be to replace it. But you need to make sure it is the control board that is faulty. It could also be the relay, bad wiring, and other key parts that make up this system.
To learn more about troubleshooting your Dometic AC control board and other parts, just continue to read our article. It looks into the problem to provide you with the best information possible to help you get this problem solved fast.
You may find that any technician you contact will simply tell you to replace the unit. That is if the control board is the problem and has failed in some way.
That seems to be the only repair we have come across for this air conditioning component. One owner created a test box and when he added a thermostat to his system, he says it runs correctly, so the problem may not lie with the control box.
Replacing this part is not going to be difficult. You just need to find the right outlet or marketplace that sells the one that is compatible with your Dometic AC model.
What we also know is that there are none to a minute amount of people who talk about troubleshooting this component. They do as we will talk about other parts that are connected to this device as they may be the source or reason why your AC unit is not working.
The replacement cost is going to be at $100 or well over $100 depending on the unit you need. You can contact Dometic to see what they say and they may have a replacement part they can send you. Talk to your service department and see what they tell you.
The location may be different from what we report here. That is due to the design of the different models of Dometic AC units. In the case of the 5-button AC unit, the control board is located on the front right of the unit.
It should be right behind the wiring diagram that is placed on the access door. Once you open up that door, you will see a capacitor and some wires blocking your way to the control board.
From there you can do your testing and removal if the controller is bad. Since the control board is inside the AC unit, you may have to get up on a ladder to access it.
That access may depend on where your access doors are. You may have to go on the roof to do this work or pull the AC unit down and work on level ground.
One instruction was to NOT use the voltmeter to make any tests. The reasoning behind this instruction is that this device does not provide you with an accurate reading.
Instead, you need to unplug the 6-pin connector, or whatever size connector you may have, and then get a 115-volt incandescent bulb to do your test. Here are the instructions for this test:
“Using a 115-volt incandescent bulb, check from terminal 5 (white-common) to the other terminals to determine if a particular circuit is completed through the board. If the circuit is completed, the light will illuminate.
- Terminal 1 is a blue wire and is the compressor circuit.
- Terminal 2 is a black wire and is a High Fan circuit.
- Terminal 3 is a yellow wire and is a Medium Fan circuit.
- Terminal 4 is a red wire and is a Low Fan circuit.
- Terminal 5 is a white wire and is Common 115 V.
- Terminal 6 is a green/yellow wire and is casing ground.” (source)
After doing these tests and the AC unit is not working, then you have a different source for your problem.
If this wiring diagram is not matching what you see in your current RV’s air conditioning unit, then we would advise you to contact Dometic to see if they will send you one.
Different air conditioners will have different wiring diagrams. Check your manual as well to see if there is one on its pages. It may not be in the owner’s manual but it could be in a service manual that some companies provide.
Or contact your local Dometic dealer to see what they have available. It is not easy to match up every air conditioner Dometic has made over the years with just one diagram.
According to the information we have come across, it is not hard to either replace the control board or find a new one. But first, how to replace one of these units so you can get your AC unit working again.
1. Replacing the control box
The first step is to shut off the power to your air conditioner. The second step would be to disconnect the wires. Make sure to mark each wire so you know where they go when you are ready to connect them.
The third step would be to disconnect the current control box and pull it out of its position. While you are doing this, you may need to remove the anti-freezing sensor so you can get the control box out without damaging anything.
After you have done all of that, take your replacement unit and put it in the old control box’s place. The fifth step would be to hook the anti-freezing sensor back up and put it in place as well as connect all the wires.
Re-connecting your wires will take the most time. You can take photos of the wires before you disconnect them, etc., and use those photos to guide your work. Some people suggest using end-to-end wire nuts to make your connections but that is up to you
You should use electrical tape as a back up and to make sure there are no opportunities for the wire to cross and create a short.
2. Where to find a control box
When you start looking for a replacement, make sure you have the model and serial numbers of both the control box and the AC unit. This will make it easier to find the right replacement.
We checked Dometic’s website and it does have a list of air conditioner parts and accessories on its web pages. However, there is a little note underneath the description stating it is not available online.
The website has a cart and checkout system but it seems that it is limited use or access to checkout. But that is okay, as you can find these parts at RV Parts Nation but you can expect to pay just under $200 for one model.
Amazon has several models available and the price range is from roughly $75 to well over $100. There are many other locations where you can pick this part up. The prices they charge will vary but they may be close to you so you do not lose any time fixing your AC unit.
The first place to go to would be Dometic’s website. They have a link on their support page where you can find the manual that you need. The link says FAQs, product manuals, and brochures.
Next, you can head over to our go-to manual website to view or download a copy for your records. It may take a little searching but you should be able to find what you need on that website. Just be prepared to pay for any downloading you do.
Then you can always do your own search for a more user-friendly website to get a copy of the manual. Another option would be to contact your local Dometic dealer and see if they hand out copies to customers.
Getting a manual should not be a difficult task as Dometic continues to make its air conditioning models. The YouTube video below should also be of some value to you as it shows step-by-step instructions on how to replace your control box.
Depending on your model of air conditioner, you may find that there is always something going wrong at the worst time possible. When your air conditioner, no matter the model, does not turn on when you need it on, here are some steps to take to locate the problem.
1. Operation- this would be more of a matter of user error than anything else. Different Dometic AC models have different operating instructions and it is easy to make a mistake.
Review those operating instructions for your specific model to make sure you are doing everything right. Keep in mind that the unit won’t turn on if the temperature level is at the set mark on the thermostat.
2. AC Voltage- the correcting voltage operating range is between 103 and 126.5 volts AC. You need to take the reading at the unit’s power supply leads. You will need to do two tests, one when the AC unit is off and one when it is under load.
If the air conditioner is not operating within that range, you will need to find the problem and repair it.
3. DC Voltage- if your unit has a DC supplied power control then you need to test it to see if it is receiving the proper amount of volts. The range for this option is between 10 to 16 VDC.
If your tests indicate otherwise, then you need to track down the problem and make the necessary repairs.
4. Breaker- this may have tripped for any number of reasons. Make sure to check to see that it has not tripped and that power is getting through to your air conditioner.
You can do that by taking an amp reading at the unit AC voltage supply line. If there is no power getting through, then you know where to look for the problem.
5. Wiring- this may seem like a minor component in comparison to everything else but if you have a bad connection, your AC unit will not operate. Check for corrosion, loose connections, and broken wires, and make sure to check the 6-pin connector to make sure it is tight.
6. Fuse- check for continuity first. The fuse may not look like it blew but it may have. Pull it out and do the test. If there is no continuity then the fuse is bad and needs to be replaced.
Also, you can do a DC voltmeter test to see if there is voltage. Put one lead on the fuse end and the other to the ground to see if there is voltage. If only one side has voltage, then the fuse is bad and needs to be replaced.
7. Thermostat- these can malfunction easily and when they do you should not be seeing your air conditioner operate. Use your meters to test the thermostats to see if they are functioning right.
8. Misc.- other components to check would be the cable array, ambient temperature, and the AC power module board.
It is given that electronic components in your RV or trailer will break down. The key is to make sure you have the right tools to diagnose the problem and then replace the failed part or parts.
The drawback to working on this issue yourself is that you may end up replacing more parts than you should and the problem may still continue. Make sure to get expert help when you are not sure what the source of the problem is or what the right fix should be.