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Mdk0420

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Posted: 05/19/23 09:43pm

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I got my soft start but I am having install issues. If you have any insight there, here is the link: https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30394528/p/1.cfm

It did not solve my issue but its quite possible I got wiring messed up or I'm not doing something correctly. Now the soft start trips with a "Stall" error instead of my generator tripping lol.

I did not run any additional metering tests because it was getting late. I hooked the soft start on, gave it a few runs to try it and it just made my problems worse for the time being because now instead of a chance the generator trips, the soft start has the "Stall" error 100% of the time.

As far as the short cycling goes I'm not sure what protections are on this unit. I did get the model number to it though. It is a Dometic Duo Therm 59516.331 AC unit. It is 13.5k BTUs. Not a very big unit. Whenever I short cycle I do it on purpose shutting down the unit then starting it back up after about 15-30 seconds.

Also note that I did NOT test the 12v battery theory yet. That could still very well be an issue of it forcing a short cycle if the inverter is cutting the thermostat on and off. This will be another thing I test out this weekend. Trips in a week so gotta figure it all out by then lol

JBarca

Radnor, Ohio, USA

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Posted: 05/20/23 06:27am

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Bobbo wrote:

The thermostat SHOULD prevent short cycling.

Assuming Mdk4020 is still on his original older Dometic control board, and T stat from 2002/2003, he might still be on the older bi-metal controls T stats. The mechanical and bi-metal T-stats were not smart enough to create a timing function to prevent short cycling. The older analog T stat may also have had the issue.

Even a new non-ducted AC with mechanical controls has the short-cycle ability issue.

When the electronic T stats came to be, many of them had the compressor timer to prevent short cycling.

John & Cindy

2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
CC, SB, Lariat & FX4 package
21,000 GCWR, 11,000 GVWR
Ford Tow Command
1,700# Reese HP hitch & HP Dual Cam
2 1/2" Towbeast Receiver

2004 Sunline Solaris T310SR
(I wish we were camping!)

Mdk0420

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Posted: 05/20/23 09:17pm

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JBarca wrote:

Bobbo wrote:

The thermostat SHOULD prevent short cycling.

The AC unit is original from what I can tell. I did not look into the thermostat however the unit is dated for 2002. I know for sure that I can short cycle it manually just by flipping it to off and then back to cold. I don't know if there is any logic for when the AC shuts off automatically though. I'm not familiar with these systems at all.

* This post was edited 05/21/23 07:22am by Mdk0420 *

JBarca

Radnor, Ohio, USA

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Posted: 05/21/23 08:38am

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Hi Mdk4020,

I'll respond here in your generator post, so it ties together better.

Here are a few things to help explain the older Brisk Air controls that apply to your 2002 AC system. There are three main parts to the AC system in controls.

1. The roof unit. This is what is in the roof itself. The roof unit has fan and compressor motors, motor capacitors, and a wiring harness with a 6-wire white plastic plug into a control box inside the camper. That is the extent of the controls on the roof. There are no contactors or other control devices up on the roof to start or stop the motors. Motor control comes from the control box.

Look like this. The silver junction box houses the capacitors.
[image]

Inside the capacitor junction box. NOTE: pending the age and vintage of the roof unit, you may or may not have 2 capacitors in this box.
[image]

The wiring diagram from the side of the capacitor box
[image]

NOTE: The little black capacitor is called out at "COMP STARTER" on that wiring diag. This extra smaller capacitor is not always used, it helps the compressor get started by boosting the start voltage as that vintage compressor needs the extra help.

The other capacitor is a split capacitor, part of it for the fan, the other part for the compressor the Mfd ratings are different for each part. This split capacitor comes in a few shapes, round and sometimes white or silver or oval again pending the vintage. Here is the top of a round silver one.
[image]

2. The control box, is a silver metal box inside the camper up in the ceiling where the air intake grill is and the mesh filter. This box is where the fan and motor contactors (relays) are located on a PC board. The 6 wire white plug from the roof unit plugs into this box.

NOTE: There are a few versions of this control box. This picture is from the older analog T stat system.
[image]

At this point, we (nor you) know if you are on the analog or the bi-metal control box. Those are the 2 main types of control boxes; they are wired a little differently and have different control power sources.

The analog control uses 12 VDC from the camper DC system to power up the control board.

The bi-metal controls use 120 VAC to run a transformer on the control box board to create the control voltage to run the AC controls.

Your 2002 camper might be on either of those 2 control boxes. Ideally, you understand what you have for now and future troubleshooting.

3. The T stat. The T stat sends signals to the control box to run the roof unit or not. There are other features the T stat does, but again the analog T stat and the bi-metal T stat are different. We need to know which you have.

This pic is of the analog T stat.
[image]

Behind the cover of the T stat
[image]

The above is more to help you understand how the 3 main parts of the AC controls work. There is more going on with the T stat, the furnace interlocks, and possibly why your genny is having issues, but I need to know if you are on the analog control or the bi-metal.

Each main control part has different part numbers. The roof unit you posted the model number for is only the roof unit. The roof unit works with many different control systems.

The control box has its own part number, and so does the T stat.

I can tell which vintage you have by the looks of the T stat. Please post a pic of your T stat. . If it is like the T stat above in my pic, you are on the analog system. The bi-metal system looks very different. I do not have a pic handy of that T stat.

Now to your Micor air. I'm not sure if you sorted out your wiring issue yet. Here are a few big-picture things.

Here is your wiring diagram from the other post
https://gcdnb.pbrd.co/images/muahNFRxR0uK.jpg

When going with the Micor air, you have to abandon the small black capacitor called COMP STARTER on the wiring diagram.

The color codes can be confusing. These pics from my last Micro Air install may help. This is a newer Dometic Brisk air unit, but the roof unit wiring should align with yours.

Here is the blue compressor tie-in that is calling out. I used a black wire to extend the Micro air black wire
[image]

The Micro air (MA) cable casing is gray; it shows the brown (MA)-to-white (DOM)from the compressor (must be the white from the compressor) and black (my wire)-to-black (MA) connections and the red (MA) plugs into the capacitor red, and the white MA with the yellow connection hood also plugs into the capacitor.
[image]

Here is a link to my Flickr photo site with more pic of the micro air install, which may help.
https://www.flickr.com/photos/camper-johnb/albums/72177720307672421

The Micro air needs the first 5 starts to work right to train (learn) the unit how to optimize the starting profile. There are instructions on how to do this on a genny. See page 26 in the Micro Air instructions. https://www.micro-air.com/support-docume........tion_Guide_for_Dometic_Family_RV_ACs.pdf

Since you had a few messed up starts on the first 5 starts, I'm unsure how to reset the starts. And I'm unsure how the soft-start will react to those messed-up first starts. You may have to call them on Monday on how to reset the learning process to get the system optimized.

I hope this helps, and please let me know about your T stat; I can explain the rest of the AC controls for the future once I know which you have if you want.

Let us know how it goes.

John

Mdk0420

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Posted: 05/21/23 01:15pm

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Great stuff! That's exactly what I'm looking at lol. I had the 2 capacitor setup. I do not have a digital display like yours. Just a few switches that change from on, auto for fan control, temp control and a setting for cool, off and heat.

I got the soft start done correctly and everything is working smoothly now. I now am drawing between 13.5-16amps on the tests I did with a voltage drop only down to 114v. The surge is much lighter now. Even tested it while running the microwave and it still started up.

The other plus on the soft starter is that the micro air that you recommended has a built in 3 minute cycle period so it cannot short cycle my AC anymore either. If I try it just gets an error and then clears after 3 minutes and starts up again (was trying to force a short cycle but doesn't work so the 16amp draw was all I was able to get now).

Note that this was without the battery installed still but because the surge is less, there's still a possibility that the battery being hooked up would help keep the control unit functioning since it would have a good 12v connection. When the surge hits I wouldn't be surprised if it dropped down to under 10v on the DC side.

Unfortunately I already had things apart before testing the battery theory but now that my voltage drops aren't crazy that isn't something I can test without hooking all the old start components back up lol.

Thank you for the recommendation on the soft starter! Worked great and in the end it seems to of solved all of my issues.

* This post was edited 05/21/23 07:40pm by Mdk0420 *

JBarca

Radnor, Ohio, USA

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Posted: 05/22/23 07:08am

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Mdk,

You are welcome, and it sounds like you have everything up and going Great!

Now to your T-stat and what kind you have

Mdk0420 wrote:

Opps...

. OK, let's try this again.

The T-stat shown in this picture is the cream-colored rectangular-shaped bottom device that says, "Duo-Therm by Domitic". This vintage is the analog-style T stat that works with the analog control box. This control box requires a separate 12 VDC source run to the control box to operate the controls. The camper 12-volt DC system provides this. The 120 VAC is fed to that box, but it only powers the motors on the roof unit.
[image]

The digital display above the T-stat with the word (Acu-rite) is a 2, AAA battery-operated remote thermometer. I have the remote sensor inside the fridge to tell what temp the fridge is doing without opening the door. It is 34.7 F inside the refrigerator. The 70.4 F is the ambient temp in the room. This display has nothing to do with the AC unit or the furnace. LOL.... sorry about that; it just came along in the pic.

I hunted down a pic of the vintage before the analog control T-stat. This is called the "Bi-metal" system. This pic shows the T-stat that works with the Bi-metal control box. This bi-metal control box only had 120 VAC come to the control box up in the ceiling. An onboard transformer created the control voltage to work with the T-stat and power the control board to turn the relays on and off to control the roof unit. This system has no short cycle protection; you are supposed to wait and not fiddle with the on/off buttons or the temp slider. In automatic, the system takes care of itself. The two vintages of the system cannot interchange T stat or control boxes. They are specific to the technology of the time.
[image]

OK, now curious as I am "into" the Sunline brand of camper, what T stat is in your 2003 model year camper? And you know what month and year it was manufactured? This info is in the binder manual or the VIN tag on the front left outside of the camper if you can still read the tag. The model years rolled mid-year, sort of like the car industry.

Have a good campout,

John