It’s been some time since my last update.
This past week (July 12 to be exact) one of my rooftop AC units decided to stop working. Of course, it was on the hottest day so far of the year.
Like many of you, I travel with an extensive set of tools so I’m able to handle most anything. Thank goodness I’m fairly handy with mechanical, electrical, electronics, plumbing, etc. One of my many jobs during my life was working on medical equipment. I repaired things like beds, laboratory equipment, X-ray machines, patient monitors and other equipment.
The AC unit that acted up is the front one. It ran fine all day. Around 6 PM, the AC unit cycled on, the fan started and a few seconds later I heard a hum as the compressor tried to start and then it kicked out. About 30 seconds later the compressor tried once again with the same result of not starting.
Considering it was late in the day and I was enjoying a cocktail, I decided it could wait until morning. In the meantime, I let the rear unit run and closed off most of the vents in the bedroom/bath area to force the air toward the front. It worked well over night.
The morning arrived and up the ladder I go armed with a screwdriver and a multimeter.
First step is to remove the cover on the AC unit. The photo below shows both AC units.
The discolored area on the rear one is where the small solar panel was mounted. It’s supposed to help keep the house batteries top off. However at a 5-watt rating don’t expect much. Plus mine was dead so I took it off and tossed it.
Here is what the guts look like inside the unit.
This photo shows the access panel to the wiring and the start and run capacitors for the compressor and fan motors.
Here’s the small rat’s nest of wires on the inside.
First thing I decided to do was look for bad connections or obvious problems. None were found.
Next, I ohmed out the compressor to make sure a winding hadn’t opened. Readings were what I would except on the start and run windings. I didn’t write it down but it was about 4 ohms for the start winding and something like 8ish ohms for the run winding.
Here you can see the start capacitor. It’s the black one.
I loosened the screw on the strap that holds that 3 capacitors (Compressor start, Compressor run, and fan run) and removed the start capacitor.
Here I pulled off the start relay. Hard to see in the photo but the small round button on the top of the cap looked like it was bulging out which is an indication of a bad cap.
This photo shows the part number of the start capacitor.
Thinking I had a bad start capacitor, I decided to verify my belief by taking the start cap from the working unit and put it in the nonworking one. Yep, the nonworking unit started up.
I decided to leave the start cap from the rear unit in the front unit. The way we were parked the front of the coach was exposed to direct sun light in the afternoon. Figured this would help keep the coach more comfortable as I continued to work on the AC problem.
We were in the College Park, MD area when this happened staying at the Cherry Hill RV Park. Great park by the way. I checked with the office and they hooked me up with a RV/Marine shop that was only 1 mile away. They had the parts I needed.
Here is the run cap kit I bought from them.
Another view of the cap kit.
Here is what the capacitor looks like removed from the bag. Has the start relay and shinny new wires on it!
Here I’ve hooked it up.
As I was hooking up the start cap to the rear unit (remember I had taken the rear start cap and put it on the front one), I noticed a clear, sticky liquid at the bottom of the compartment holding the capacitors. What ta heck?
I pulled out the large run capacitor. Here is what I found.
Someone in the past tried to ‘fix’ it by using a sealant to plug a hole in the capacitor. The shinny stuff on the left of side of the capacitor is the electrolyte leaking from it.
This photo shows the number of wires hooked up to it.
Let’s take a photo of the part number and run down to the local RV/Marine dealer.
The dealer didn’t have that capacitor in stock but was able to order it for delivery the following day.
Here I show the new capacitor.
After cleaning up the mess from the leak and installing the new run capacitor, I did a test run. Yeah! All is working.
It’s probably just my imagination but I swear the rear unit with the new run start and run capacitor is quieter now.
After the successful test run, I put everything together.
I decided to go ahead and replace the start and run capacitor on the other unit. Figured this was a good idea considering the units are about 14 years old. My experience has been that around 12 years or so these types of capacitors are prone to failure.
With time on my side, I ordered it online and saved a few dollars. It’s a good thing I ordered it as 2 days later the old start capacitor failed! New one to the rescue!
That wraps up this project.
Hope it helps someone should you have the same problem.
Take care,
Dave
Linear Mode
