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Old 08-30-2020, 03:08 PM   #1
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Brand: Thor Motor Coach
State: Maryland
Posts: 9
THOR #17635
AC woes

First post here asking for assistance, so I guess this is my introduction. Sorry in advance for the long post but I had tried to do as much research and testing before actually posting something.

Background.... We bought a used 2018 Thor Aria in December of 2019. This unit has two of the AirXcel Mach 10 15K BTU Heat Pumps. While heading to camp the other week, both appeared to have failed at the same exact time. We were able to tolerate it with leaving the windows open and having some fans run but now I need to fix them.

After troubleshooting, it appears I have two different problems.

The unit in the front, upon turning it on, the fan works, the compressor tries to start, buzzes for a few seconds, then stops. After another 15 seconds give or take it repeats. I would expect this to have been a capacitor problem but after changing them, even though visually they appear ok, the problem persists. There is high pressure relay switch that I am going to try next. In the event that neither of these work, I am assuming it means my compressor is locked up and that the entire unit will need to be replaced.

The unit in the rear, upon turning it on. the fan works and the compressor actually does start. The issue is that it is not blowing cold air. The tube going to the evaporator coil is cool to the touch, not cold. I am assuming there is a freon leak and it is just not cooling enough to blow air. Since these are sealed units, again, it appears the entire unit will need to be replaced.

So, here we are in 2020, crazy times, and everybody is out camping. As a result, it appears that there are shortages where the air conditioners/heat pumps are out of stock.

On to my questions...

-Do the above scenarios I have described make sense? Is there something else I could test or replace?

-I believe I can replace these units myself. If so, should I strive to get the same model? Dometic has units and I have read in other places that you can keep the same thermostats, control panel, etc. I have the Firefly control panel system. Other people/places have said the wiring won't match and I would need to replace other components like the thermostat.

-There is a newer model AirXcel unit, Mach 15, but it is air conditioner only. You can buy an optional heating element. Different than a heat pump but still provides heat. I also have an electric fireplace and propane furnace. Would there really be a benefit to replacing with a heat pump or would an AC with heating element be fine?

-If I replace the unit with an AC with heating element, any idea if that would work with the existing system/wiring? Vague question here I know but figured I would ask.

Thanks in advance for reading all of this. I look forward to any input.
-Bill

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Old 09-01-2020, 08:06 PM   #2
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THOR #17635
Wow, 2 days and no responses. I am assuming then that I have kind of answered my questions in that I will need to replace the existing units. It is unfortunate timing right now as apparently due to all the extra camping going on this year most all AC's/Heat Pumps are back ordered and manufacturing can not make them for some reason. Still trying to get a hold of AirXcel again but all I get is voice mail boxes or statements saying they are closed when I call when they should not be.

Skipping the scenarios, does anyone have any information or references to installing other brand systems using existing Firefly controllers and issues that may cause?

Thanks.
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Old 09-01-2020, 08:41 PM   #3
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THOR #20289
Well your diagnosis of both failures seems correct, although the compressor not starting could be due to a voltage problem, perhaps due to a small shore power cord or a bad shore power outlet. Check the voltage at the A/C power terminals when it tries to start. The high inrush current will definitely drop the voltage but anything more than 5 volts is a problem.

The other unit does sound like low freon, but you will probably spend a decent fraction of a new unit's cost to service it.

I don't have any suggestions on replacements.
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Old 09-01-2020, 11:16 PM   #4
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with both seemingly 'failing' at the exact same time, points more toward a POWER issue, not an air conditioner issue.

WHERE and WHAT SIZE power source are you plugged into for power?
Does it do the exact same when running the GENERATOR?
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Old 09-01-2020, 11:17 PM   #5
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THOR #11781
You'll have a hard time finding someone to service roof top A/C units. They are designed to be replaced upon failure not serviced. Sure, you may find the parts to do it yourself and you may find a service company willing to work on them, but the cost will probably be close or equal to the price of new units. The new units will have some warranty and the repairs will probably not.
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Old 09-01-2020, 11:45 PM   #6
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THOR #12726
have you ever run the a/c systems on the 15amp adapter? if so being under powered might have burned up the compressor,rear a/c check the air filter and check the roof top unit condensor/evaporator make sure they are clean and not plugged up, If you have to replace them I would go with one with a heat pump I use my motor home in the winter and run the heat pumps off the generator as the engine heat wont warm anything past the drivers seat.
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Old 09-02-2020, 12:02 AM   #7
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Model: 2020 Magnitude SV34
State: Florida
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THOR #12751
Quote:
Originally Posted by BillHill View Post
Wow, 2 days and no responses. I am assuming then that I have kind of answered my questions in that I will need to replace the existing units. It is unfortunate timing right now as apparently due to all the extra camping going on this year most all AC's/Heat Pumps are back ordered and manufacturing can not make them for some reason. Still trying to get a hold of AirXcel again but all I get is voice mail boxes or statements saying they are closed when I call when they should not be.

Skipping the scenarios, does anyone have any information or references to installing other brand systems using existing Firefly controllers and issues that may cause?

Thanks.
Do you have the Firefly Multiplex system in your coach that controls the A/C units? If so, let me know and I will post about issues I had that were related to the Firefly system.

I'm not sure it is the same problem you are experiencing given your descriptions of the two units but I will be happy to share my experience if you have the Firefly system and how it was resolved.
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Old 09-02-2020, 12:55 AM   #8
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Originally Posted by TurnerFam View Post
with both seemingly 'failing' at the exact same time, points more toward a POWER issue, not an air conditioner issue.

WHERE and WHAT SIZE power source are you plugged into for power?
Does it do the exact same when running the GENERATOR?
Thanks for responding. I always use 50 amp when plugging in. I have never actually tried 30 amp and only once have used 15 amp just to test it. It does the same thing regardless of shore power or generator. It is interesting actually as I can hear the generator surge when the compressor attempts to kick on when I do try it on generator. When plugged in I am using the power cord that is attached to the system and I also use a surge protector.

Now that I am more confident that they are 2 different problems. My guess is that the one system has had a leak and just finally got low enough to notice when coupled with the fact that the other was not working. Since it appears to be locked compressor on one and low freon on the other it appears to more just bad timing than anything.

After speaking to someone this evening about it I am going to see if I can either get someone to install a tap and try to repair the leak and fix recharge it. Otherwise I can borrow the gauges from someone else and give it a shot myself. Since I can't get any replacement right now due to the shortages it might be my only option for the near term.
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Old 09-02-2020, 12:57 AM   #9
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THOR #17635
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Originally Posted by Judge View Post
Do you have the Firefly Multiplex system in your coach that controls the A/C units? If so, let me know and I will post about issues I had that were related to the Firefly system.

I'm not sure it is the same problem you are experiencing given your descriptions of the two units but I will be happy to share my experience if you have the Firefly system and how it was resolved.

Yes sir, I have the Firefly Vegatouch Spectrum system. The system itself appears fine but any insight into previous problems you have experienced might be helpful. The only thing I have seen as an issue so far regarding the Firefly is the iPhone app. When starting it sometimes it says sensor error when trying to get the information for the current temperature. Never see that issue directly off the panel so I assume it is just the app.
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Old 09-02-2020, 10:43 AM   #10
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Originally Posted by BillHill View Post
Yes sir, I have the Firefly Vegatouch Spectrum system. The system itself appears fine but any insight into previous problems you have experienced might be helpful. The only thing I have seen as an issue so far regarding the Firefly is the iPhone app. When starting it sometimes it says sensor error when trying to get the information for the current temperature. Never see that issue directly off the panel so I assume it is just the app.
So I don't have the Vegatouch model in my 2020 Magnitude but there are common components with the Firefly multiplex system so I will share my experience.

On one hand, it is strange that you are having issues with both A/C units (as was my case) and the common denominator is the Firefly system controls both.

You problems sound different than mine but it is worth giving you another data point. Back in March and April I started having issues with both A/C units. The system would be running ok but then I would start experiencing one of the following different scenarios:

- The fans would run but the compressors would not even though the panel was calling for cooling.

- The compressors would run but the fans would not.

- When one of the above issues would occur, the control panel would not turn off the A/C units or the fans.

The only way I could recover was to shut down the 12V to the coach to turn off the FireFly system and cause it to reboot. Then things would work ok for a bit and then the problems would start again. After troubleshooting with Firefly, it was determined I had a bad G7a main board. I had it replaced under warranty. Rebooting the system temporarily fixed the issue every time. Since I had the mainboard replaced, I have not had any more problems and we have used the A/C a lot.

It would be easy for you to shut down the 12V on your coach and reboot the system to see if it has any effect..... I am going to guess it won't but it is worth a try.

Since you coach was used when you bought it you don't have a full history. To me it does sound like different issues with each unit. The other common denominator in this case (as has been mentioned) is power.

The coach could have experienced a power surge causing damage to both units if they were running and a surge protector wasn't being used.

With the unit running but not cooling well, it might be worth climbing on the roof to make sure the condensor is clean and not obstructed. I know the coach is only a couple years old but depending on where it was used and how it was stored, the condensor may be very dirty and causing airflow restrictions that are killing its performance.

While you are up there, you can look to see of the condensor fan is running on the other unit is running and if it is only the compressor not starting.

I assume you have tried just running only one unit at a time... that could help determine if you have an issue with your power source and the units are not getting enough voltage to run properly. A voltage issue would be amplified when trying to run both units at the same time.
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Old 09-02-2020, 08:01 PM   #11
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Brand: Thor Motor Coach
State: Maryland
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THOR #17635
Quote:
Originally Posted by Judge View Post
So I don't have the Vegatouch model in my 2020 Magnitude but there are common components with the Firefly multiplex system so I will share my experience.

On one hand, it is strange that you are having issues with both A/C units (as was my case) and the common denominator is the Firefly system controls both.

You problems sound different than mine but it is worth giving you another data point. Back in March and April I started having issues with both A/C units. The system would be running ok but then I would start experiencing one of the following different scenarios:

- The fans would run but the compressors would not even though the panel was calling for cooling.

- The compressors would run but the fans would not.

- When one of the above issues would occur, the control panel would not turn off the A/C units or the fans.

The only way I could recover was to shut down the 12V to the coach to turn off the FireFly system and cause it to reboot. Then things would work ok for a bit and then the problems would start again. After troubleshooting with Firefly, it was determined I had a bad G7a main board. I had it replaced under warranty. Rebooting the system temporarily fixed the issue every time. Since I had the mainboard replaced, I have not had any more problems and we have used the A/C a lot.

It would be easy for you to shut down the 12V on your coach and reboot the system to see if it has any effect..... I am going to guess it won't but it is worth a try.

Since you coach was used when you bought it you don't have a full history. To me it does sound like different issues with each unit. The other common denominator in this case (as has been mentioned) is power.

The coach could have experienced a power surge causing damage to both units if they were running and a surge protector wasn't being used.

With the unit running but not cooling well, it might be worth climbing on the roof to make sure the condensor is clean and not obstructed. I know the coach is only a couple years old but depending on where it was used and how it was stored, the condensor may be very dirty and causing airflow restrictions that are killing its performance.

While you are up there, you can look to see of the condensor fan is running on the other unit is running and if it is only the compressor not starting.

I assume you have tried just running only one unit at a time... that could help determine if you have an issue with your power source and the units are not getting enough voltage to run properly. A voltage issue would be amplified when trying to run both units at the same time.
Thanks. It can't hurt to try the reset for sure. I had just read the Firefly documentation and on one of the last pages there is a section about resetting the PMM in a similar fashion.

I have tried running only one unit at a time, same issues. Also I have been on top certainly and made sure everything is cleared out. Wasn't dirty but surprisingly did have little pieces of styrofoam stuck in there, just bad craftsmanship.

I appreciate all the help. At this point, my next post on this is likely to be I just replaced them or got them recharged but if something different takes place such as one of the resets I will certainly post that as well for other's reference.
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Old 03-28-2021, 01:48 PM   #12
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Brand: Thor Motor Coach
State: Maryland
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THOR #17635
The day finally came. For anyone still following or interested in this or maybe even in the future needs information, both AC units were bad.

After the Covid-19 backorder delay was resolved, I purchased 2 new units from camping world and had them shipped to me. They weigh about 80 pounds each so I rented a boom forklift to get them into position to transfer them down off the RV and then the new ones back on.

Removal was simple. Turn off the breakers, remove the cowl, remove 3 long screws from the existing unit that fastens the system to the roof. Inside is some sort of power module that is fastened to the unit with 2 bolts. Remove that and then pull the air temp sensor from the fins.

Putting the new ones back on, I had to drill a hole in the bottom of the unit, for some reason they did not already have the hole there. Bold the power module back in and reinsert the temp sensor back into the fins. Line up the new unit with the existing holes, put the cover back on.

All in all was simple once going so don't let it intimidate you if yours go out also. I am sure I saved a ton of time and a bunch of money from having to get them installed by a dealer.
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