2017 AI GT A/C Question

[Land Stitchy]

Just purchased a hardly used 2017 Interstate GT. First time RV owner but lifetime boater so I have the basic system knowledge. Been going through all the systems and surprisingly everything works as advertised. This forum has been extremely helpful in answering questions but I have finally come to just one issue that I cannot resolve. Read every post that came up in searches on the topic and nothing covers my issue so here is my first cry for help.

AI is plugged in at home so working on 20A service. Turn on the A/C when it is 95 degrees inside. Watching the Power Control System closely after turning on A/C. Nothing else in the coach is turned on. A few amps to run the A/C fan, then the quick surge as the compressor turns on. Then the amps fluctuate from 13 to 23 amps erratically . After two or three times going over 20 amps the system sheds the H/W and A/C as expected. Wait two minutes and it comes back on - as expected. Same erratic fluctuating amp draw. Power Control sheds A/C again. On the third shut down the Power control system turns off altogether and goes dark. Wait 10 minutes and nothing happens so manually turn PCS back on. Start the whole process again. No change.

Of all the manuals that came with the vehicle I cannot find anything on the PCS. So the questions are:
1. Is this normal for the PCS in that it thinks there is a continuous fault and shuts down completely? Complete power off - dark.
2. Do you think there is a problem with the A/C that is causing the amp fluctuation and frequent spikes over 20A? Low Freon or whatever they use now a days?
3. Should I just tell PCS that it is 30A and see what happens? (Pop house breaker?)

AI owners manual pretty thin on information (you all know that) and already read the book on Kindle which doesn't cover this specific topic. So before going to an A/C service guy on a relatively new, but out of warrantee unit I thought I would ask the group.

[FlyFishinRVr]

First, welcome, and congrats on the new (to you) GT.

Am I understanding this right, and you're trying to pull upwards of 23A from a 20A house circuit??? If so, couple things. First, most house circuits are 15A, but even if yours is 20A (I assume you're getting that value from the circuit breaker?), trying to pull 23A from it can result in all manner of "bad things", including what you're experiencing. Second, if I remember my panel correctly, can't you switch it to 30A? If yours is set to 20A, and you're bouncing off 23A, maybe it's trying to intervene and shed the load, and then when it drops below 20A, it tries turning it back on....on and on it goes.

Try this: First, see if switching your panel to 30A service makes a difference. Second, confirm you have nothing, and I mean zero, connected to that house circuit other than the RV. If it's really a 20A breaker and you haven't popped it yet, you might be able to handle the RV's A/C, but I think it's going to be a crap shoot based on grid voltage (i.e. hot days with low grid voltage and you'll be out of luck, mid winter with really good grid voltage and you may be OK).

[Land Stitchy]

Thank you for the reply.

I am not sure of the house breaker rating. I have not tripped the house breaker yet so that is not my current (no pun intended) concern.

I was referring to the Power Control System panel in the vehicle that has two option settings - 20A and 30A. As I understand it should be set to 20A when using a plug adaptor with the shore power cord to plug into a wall socket. It can be left in 30A when shore power is plugged into the appropriate twist lock 30A service.

However, my real question is - should the A/C unit be constantly cycling above 20A? If so this means that I cannot use my A/C on the generator or when plugged into 20A service. That cannot be true. BTW - when I run the A/C on generator the same thing happens, it fluctuates between 13A and 23A draw and the Power Control System shuts it off.

My second question is - the Power Control System turns off completely (panel went dark) after it shed the A/C three times. Is this part of the Power Control System design?

I am hoping that there is only a problem with the A/C that can be fixed. Before I drive over to an A/C place I was looking for some confirmation from the forum.

[InterBlog]

This information may or may not assist the discussion: what does the manufacturer state that your A/C model draws, in terms of amperage?

I can tell you that ours needs 3.5A for the fan and 9.5A for the compressor, for a total of 13A, but we have an older Interstate with a smaller roof A/C (11,000 BTU, and IIRC, the newer ones are something like 15,500 BTU).

[Land Stitchy]

Thanks Rivet,

Will check the documentation that I have but I think it is 11000 BTU. The A/C did operate one single time a few days ago and it stayed at a steady 13 amps without any problems. That matches your experience. I am now suspecting a low gas or capacitor problem.

[AirstreamInc]

Hi Land Stitchy,

Please call our customer service and technical support team at*1 (877) 596-6111, option 2 so we can learn more and help.

Thanks.

[UKDUDE]

I have never seen my AC use more than around 13A in the full Arizona heat! It does seem like you have an AC issue.
Makes no difference whether the generator is running (20A) or plugged into a standard socket at home (15A).
But I would never set the Power Control System to 30A unless I'm absolutely certain I'm connected to a 30A circuit. You risk damaging something!

[Land Stitchy]

Airstream Tech support and friends in the A/C business concur that it is likely a A/C capacitor problem. Scheduling service call with an Dometic pro next week. Will post findings at the conclusion.

[FlyFishinRVr]

Originally Posted by Land Stitchy

Thank you for the reply.

I am not sure of the house breaker rating. I have not tripped the house breaker yet so that is not my current (no pun intended) concern.

I was referring to the Power Control System panel in the vehicle that has two option settings - 20A and 30A. As I understand it should be set to 20A when using a plug adaptor with the shore power cord to plug into a wall socket. It can be left in 30A when shore power is plugged into the appropriate twist lock 30A service.

However, my real question is - should the A/C unit be constantly cycling above 20A? If so this means that I cannot use my A/C on the generator or when plugged into 20A service. That cannot be true. BTW - when I run the A/C on generator the same thing happens, it fluctuates between 13A and 23A draw and the Power Control System shuts it off.

My second question is - the Power Control System turns off completely (panel went dark) after it shed the A/C three times. Is this part of the Power Control System design?

I am hoping that there is only a problem with the A/C that can be fixed. Before I drive over to an A/C place I was looking for some confirmation from the forum.

Your A/C is by Dometic and is 13,500 BTU. According to the specs, in "cooling mode" (i.e. compressor on) it consumes 1731W. Since it's a 115v unit, that means it draws 15A continuous. What we don't know is what does it draw on startup. There are many people who claim their 2500W Onan generator won't start their A/C, which would indicate on startup, the A/C can draw over 22A.

Given this, can your A/C pull 23A on startup? From the numbers and anecdotal evidence from others on the forum, it appears it can when the compressor is starting, but that should be a quick spike and then it should settle down and pull in the 15A range. Is that "normal"? Based on the number of people who have commented about their A/C not starting, I'd say it may be "common", but you'd need to ask Airstream whether it's "normal" (as in "expected").

If I get the chance this weekend, I'll put a current clamp on my A/C circuit and give it a go w/ the genny. Both need to be exercised anyway (I never use either), so it's not much more of a hassle to stick a clamp on the breaker. I bet you it goes over 20A.....

As to the behavior of the Power Control System after 3 attempts to shed the load, that should probably be discussed with Airstream. I see they chimed in already with their contact info, so hopefully they can give you some insights.

[Land Stitchy]

I do see the initial surge on start-up in the 23A range. Then it drops to 13/14A but bounces erratically between 13 and 23A. Changing Amp values roughly every second. The Power Control allows it to go momentarily over 20A three times before it actually detects a fault and sheds the load.

Airstream Tech Support confirms - if the same appliance goes over the 20A or 30A setting and sheds three times the Power Control shuts down completely and will not restart on its own. It goes dark. You can manually restart it by simply pushing the button again. This makes sense since you do not want a high amperage situation to simple cycle and repeat over a long period of time if you are not in the coach to see what is going on and take action.

I did set the Power Control to 30A. The A/C did the same thing - bouncing between 13 and 23 amps and it ran cool for two minutes before I shut it off. Probably wasn't the best idea but I wanted to isolate the problem. I suspect the prior owner was running the A/C at his house 20A without knowing he had a problem. The two times that I looked at the coach before purchase the A/C was running and it was cold inside. I did not know enough about the different systems to notice the bouncing-amp problem in the power control LED read out.

And now back to more important things - replay of today's Pebble Beach golf.

[FlyFishinRVr]

Originally Posted by Land Stitchy

I do see the initial surge on start-up in the 23A range. Then it drops to 13/14A but bounces erratically between 13 and 23A. Changing Amp values roughly every second. The Power Control allows it to go momentarily over 20A three times before it actually detects a fault and sheds the load.

Airstream Tech Support confirms - if the same appliance goes over the 20A or 30A setting and sheds three times the Power Control shuts down completely and will not restart on its own. It goes dark. You can manually restart it by simply pushing the button again. This makes sense since you do not want a high amperage situation to simple cycle and repeat over a long period of time if you are not in the coach to see what is going on and take action.

I did set the Power Control to 30A. The A/C did the same thing - bouncing between 13 and 23 amps and it ran cool for two minutes before I shut it off. Probably wasn't the best idea but I wanted to isolate the problem. I suspect the prior owner was running the A/C at his house 20A without knowing he had a problem. The two times that I looked at the coach before purchase the A/C was running and it was cold inside. I did not know enough about the different systems to notice the bouncing-amp problem in the power control LED read out.

And now back to more important things - replay of today's Pebble Beach golf.

Good to know about how the Power Control System works. Three strikes and you're out!

Setting it to 30A isn't going to hurt anything. At most it will trip the shore breaker.

Best luck with the repair.

[BurntAsphalt]

Originally Posted by Land Stitchy

Airstream Tech support and friends in the A/C business concur that it is likely a A/C capacitor problem. Scheduling service call with an Dometic pro next week. Will post findings at the conclusion.

Ask them to install a soft start capacitor while they are working on it. This gives the AI's electrical system a fighting chance to start the AC since it draws amps close to genset capacity at startup. Not sure why Dometic doesn't include a soft start on AC units going into Class Bs.

[Land Stitchy]

Well, my troubleshooting skills are a bit lacking and I jumped to a conclusion that was not right. Still searching for an answer to my problem but looking in the wrong place. I original reported the Air Conditioning amps on the Power Control Unit were cycling erratically between 13 and 23 amps which shuts down when on generator (20 amps) or with the Power Control Unit set to 20 amps.

I did some more testing tonight and found the exact same problem when running the Microwave or the Hot Water heater. To be clear I am running these units by themselves with not at the same time. So of the three main appliances they all have the same problem and are shut down by the Power Control System. Amps run wildly up and down, changing every second and no pattern, and the power control unit shuts them down after going over 20amps.

So I do not have an air conditioner problem as titled in the original post. I have a Power Control System problem or an overall electrical problem. I do not have the manual on the Power Control Unit. I sent an email tonight to Airstream Tech Support and to Precision Circuits (Power Control System manufacturer) to see what they say.

Always appreciate the feedback from the community. Will post what I find for future searchers. Really hoping it is something dumb or simple since everything else on this 2017 has worked perfectly since our purchase three weeks ago.

[amirm]

Originally Posted by BurntAsphalt

Ask them to install a soft start capacitor while they are working on it. This gives the AI's electrical system a fighting chance to start the AC since it draws amps close to genset capacity at startup. Not sure why Dometic doesn't include a soft start on AC units going into Class Bs.

I added a soft-start cap to mine and it made no difference at all. I was trying to get it to work with my inverter. I tried two different brands to no effect.

[amirm]

Originally Posted by Land Stitchy

I do not have the manual on the Power Control Unit. I sent an email tonight to Airstream Tech Support and to Precision Circuits (Power Control System manufacturer) to see what they say.

I had to do a ton of searching to find the manual for them. But I have it now in three different files. See the enclosed zip file.

To troubleshoot what is going you need an AC clamp meter. Open the breaker panel and measure the current going through the wire that is looped through the PCS. It should agree with what it is saying. Also make sure there is only one loop through it and not more.

Edit: zip file didn't work. So I enclosed the three PDFs separately.

[InterBlog]

Originally Posted by Land Stitchy

Well, my troubleshooting skills are a bit lacking and I jumped to a conclusion that was not right. ...

I did some more testing tonight and found the exact same problem when running the Microwave or the Hot Water heater.

... Amps run wildly up and down, changing every second and no pattern, and the power control unit shuts them down after going over 20amps.

.....

Actually I'd say that your troubleshooting skills were quite good, for the simple reason that you kept iterating without prejudice (in other words, without remaining married to your initial conclusion, a mistake that many people would make). None of us gets it right straight out of the blocks. Perseverance is the name of this game.

Focus on this statement of yours for a moment: "Amps run wildly up and down, changing every second and no pattern"

Now, go to this thread and look at the table I pasted at the end of the entry. What do you see? Amps running wild with no pattern, other than they were clearly going up and down.

In our case, that was being caused by a burned-out circuit trace. You have different equipment in your rig than we did at that time, but it's possible that an analogous failure may have occurred, causing a similar effect. That's what I'd look into next, if I were you.

[Land Stitchy]

Thank you for the last two responses. Very helpful.

I followed Amirm's suggestion and borrowed the proper test meter from a friend in the electronics business. Opened the main panel under the driver aft bench and hooked the coil around the neutral wire. Before connecting I noted only one neutral wire running through the Power Control System "doughnut" which is exactly what your schematic showed. No signs of loose wires or other visual problems.

Ran the Air conditioner and bingo - the Fluke meter wrapped around the neutral at the breaker panel shows a steady 13 amps with no fluctuation while the Power Control System panel LED showed the same erratic fluctuations. Same results when running the electric hot water heater. This seems to eliminate power coming in or the appliance itself.

I put in a call to Precision Circuits (manufacturer of the Power Control System) and talked to a very helpful person in technical support. He was not familiar with the symptoms that I described. He though that the "doughnut" located in the breaker panel was not likely to fail. He thought it might be a problem with the main PCS panel up forward. I removed the panel and checked all connections - no problem. He will ship out a new panel tomorrow with the promise that I would send back the old one for analysis.

Probably won't see the replacement panel until mid next week. I will check back in and document the results.

[Titus]

Do you hear the compressor cycling on and off when the amps are varying wildly? If so, might it be a bad thermostat and/or loose thermostat wire that is causing the compressor to cycle? House A/C units have a timer to prevent rapid cycling, but the Dometic may not. Or maybe it does but is broken. We go briefly over 20A but then it quickly settles down to < 20 A.

Also, not all 30A plugs are twist lock. I have never seen one at a campground that is a twist lock on the power pedestal like there is on the Airstream end.

[Land Stitchy]

I think this is Case Closed.

I got a new panel yesterday (referring to the Power Control panel behind the driver seat) from Precision Circuits. 4 screws, two quick connect electrical connections to plug in and ran the system. Air conditioner at high fan speed ran a steady 15 amps with no fluctuations. Running as expected without any power shedding. Same results with the hot water heater. Still need to test the systems on generator but it appears to be a clear resolution to the original problem - there was a fault with the power control panel.

Credit to Precision Circuits, the manufacturer of the Power Control System, for having an excellent technical support person on the phone and sending me a new power control panel without many questions. I am returning the old panel so they can diagnose it.

Thanks to everyone on this forum that took the time to provided valuable troubleshooting feedback.

[InterBlog]

Originally Posted by Land Stitchy

... I am returning the old panel so they can diagnose it. ....

I'm glad this got resolved for you, and do let us know what they diagnose. If it was, in fact, a burned-out circuit, it's one more thing that people can put on their mental watch list for troubleshooting purposes.