Coleman Mach 8 Run Capacitor

Troubleshooting our Air Conditioner

Troubleshooting our Air Conditioner – I didn’t want to repair the air conditioner, I didn’t want it to break. If you own an RV (or any house) it will break. Here is how I fixed our RV air conditioner that broke as we left Las Vegas (where it worked just fine).

This is not the first time I have dug around inside our air conditioner. RV air conditioners require maintenance, at least once a year just to clean off the heat exchanger. I also installed a Micro Air EasyStart 364 in both our air conditioners early this summer. Here is my post about the EasyStart.

At first, I thought about my install of the EasyStart and perhaps I caused the problem while installing it.

Why did it fail?

I also thought that perhaps the air conditioner broke because I was test running it from the batteries. I knew in the back of my mind, that this couldn’t be the cause — because 90% of my testing was running the front air conditioner, not the back air conditioner… and it was the back air conditioner that broke.

The fear was that perhaps the air conditioner was completely broken never to run again. This happened this spring, to our front air conditioner, which required it to be replaced. The same failure, never to run again, just happened to our friends Bill and Kathy, when they were with us in Utah. Bill heard his air conditioner fail with a loud thunk. They are still trying to find a replacement unit.

Troubleshooting our Air Conditioner

I don’t want anyone to think I am some kind of troubleshooting wizard. You may recall that my furnace also failed earlier, and as I was preparing to take it apart. I fixed it by turning on the gas valve. Sometimes I fix things by plugging them in. Some times I fix things so good, that they can never be fixed again — by anyone.

I didn’t want to get a new air conditioner, nor did I want to live with only one air conditioner, nor did I want to pay for someone else to correct an obvious problem. So according to my normal method, I decided to take it apart to try and fix it. I found the problem while troubleshooting our air conditioner and thankfully it was an easy fix.

Failures

There are only a few components that comprise an air conditioner. If the compressor fails or the freon leaks out, you will probably replace the entire unit. If a fan fails, you can replace the fan. Other than that the problem is electrical and you can fix electrical.

There are only two problems that cause electrical failure. This makes the troubleshooting easy. The problem is a “short”, which will burn a fuse or trip a circuit breaker. Short means short circuit. This means that the electricity has found a path that does not go through the device that it was intended to run.

Not every problem is a short circuit. The second more common problem is an “open” circuit. This means that the pathway is not connected and thus the electricity is not connected to the device.

Coleman Mach 8 Run Capacitor and Terminal Block
Coleman Mach 8 Run Capacitor and Terminal Block

Both shorts and opens are a question of finding the problem. I knew that since I did not trip the circuit breaker, most likely my problem was an unintended open circuit. Of course, you have to be willing to change your mind if you find a burned out fuse.

Wiring

Here is a simplified wiring diagram that Micro Air uses to help people install an easy start. The next picture is also from Micro Air which shows the inside of the junction box. There is also a specific wiring diagram inside the junction box. This picture shows the same thing, without as many lines, so this makes my explanation easier.

EasyStart 364 Wiring Diagram
EasyStart 364 Wiring Diagram this diagram would have been easier to follow if the manual would have identified that the light blue color represented the white wire.
Coleman Mach 8 Air Conditioner Wiring Junction Box
Coleman Mach 8 Air Conditioner Wiring Junction Box

#1 is the white wire from the compressor to the run capacitor. #2 is the red wire from the run capacitor to the compressor. #3 is the PTCR box which is removed when installing an EasyStart. #4 is the red wire from the PTCR which goes to the start capacitor (also removed when installing an EasyStart. #5 is the run capacitor. #6 is the purple wire which switches the power on and off. #7 is the black wire that gets power from the purple wire.

Coleman Mach 8 Run Capacitor and Terminal Block
Coleman Mach 8 Run Capacitor and Terminal Block

Caution capacitors can be dangerous!

Capacitors may have a charge — even if they are not hooked to anything. They can shock you long after they are removed from an electrical circuit. Since this is not a lesson on how to do something, I am not going to tell you how to discharge a capacitor or even how to tell which capacitors may hurt you. This is something I will only warn you about. If you don’t know what you are doing with these things, it is better to stay safe and not monkey with it.

As you can see from my picture below, there is a relay (bottom right corner) not represented in the wiring diagram or the EasyStart photo above. This caused me some concern when I was troubleshooting our air conditioner. A failed relay can cause an unintended open and could have been the source of my problem.

Coleman Mach 8 Run Capacitor
Notice that I pulled the red wire off the terminal block so I could stand up the capacitor to get a good look at it. On the left side of the picture you can see the brown wire spliced to the white wire that is part of the EasyStart installation. The extra black tape on the outside of the connector was put in to make sure that if this free-floating splice contacted anything the wires could not create a short.

Fire

It was after this that I noticed that the other brown wire (second from the left) was burned all the way through at the wire connector and wasn’t touching anything. This was an obvious problem and even if it wasn’t the only problem, this had to be corrected before anything else could be done. Thankfully the wiring diagram from the inside of the junction box showed a brown wire, associated with the relay. Following this brown wire, you could tell that it also damaged the purple wire and the black wire from the easy start.

While troubleshooting our air conditioner I found these burned connections.
While troubleshooting our air conditioner I found these burned connections.

The only question that remained was why did the brown wire burn?

The answer to this is that it was a loose connection between the wire and terminal block. It was loose because of corrosion, or age, or vibrations over time, or possibly because it wasn’t installed correctly. All causes result in increased resistance and this creates heat. In my case, this caused a small fire that disconnected the brown wire and damaged the black and purple. Since I didn’t do anything with the brown wire while installing the EasyStart, this also means that I didn’t cause the problem. (At least I didn’t cause this problem.)

In case you are still wondering, fixing these wires fixed our air conditioner. We are so happy with the result. I would have been very unhappy to have paid a repairman to find and fix such an obvious problem.

Here is the link to the Micro Air EasyStart 364

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