Can anyone advise if there are other breakers for the 2 AC units besides the ones at the foot of the bed, and if so where are they?
I would say that's it. There wouldn't be any reason for more.
The 12VDC control voltage comes off a self resetting breaker in the dash behind the kick panel in front of the passengers seat.
Mike
Ok...I am just doing some investigation about why my CC2 thermostat (4 button) does not show zone 2 and the rear AC does not work. When I disconnect the rear AC from the front, the front AC works (on gen power)
I have discussed this with many on site here.
This happened last summer, and NOW I suspect it is because I started both AC units while on 15 amp power and
may have "browned" out my rear AC (????) Is this possible ?? My AC units are the 620315.321 Duo Therm Units
-I have purchased the 5 button upgrade kit including both control boards, but have not installed it yet, due to
me troubleshooting totally before installation of the unit.
-I have checked the data line between the AC units and ran an outside cord between to confirm it was not a cable.
So, I am trying to trouble shoot everything before I pay the big bucks to have someone look at it.
That sounds like someone has messed with the dip switches up in the rear A/C unit and the Tstat don't know that you have a rear A/C unit.
Mike
If you had only 15a going to coach and tried both AC's the breaker that is outside the coach that is connected to the outlet you were plugged into would have tripped before you damaged the unit due to brown out. But, never say never.
Turbojack
Are you talking about the breakers at the foot of the bed or the front of the passenger feet?
It would/should have tripped the 15 amp breaker that fed the plug where your RV was/is plugged in. If it was to trip one of the breakers at the foot of the bed that circuit would have been overloaded, one A/C unit per breaker. This would have no effect on the DC voltage breaker that is in the dash.
Mike
What Mike said!
Each AC unit has a dedicated 120V circuit going to the breaker box at the bed. The AC's need 12DC in order to operate the control of the AC's The front AC has a circuit board that has a phone wire going to the thermostat. There should be 12 V DC at the front Circuit board which you should have since the front one works. There should also be 12VDC to the rear circuit board. Put a volt meter there and check to make sure you have 12 volts DC.
If everything has power the first thing I would do is kill the power going to the circuit boards, wait a few minutes and then reapply power. When it boots back up that might fix the problem of not seeing the rear AC unit.
You might verify that the data cable you tried is pinned out the same as the existing one. Not all cables are pinned the same.
So can I kill the power to the breaker boards by turning off the salesman switch. Sorry, not as electrical a guy as I thought!! Open up the front passenger panel and located(I think) the ac breaker. But it is only one breaker...I suspect for both units?
1. No. that buss that has about 4 breakers are fed all the time from/through a manual reset breaker in the basement behind the fiberglass cover. IIRC that is called the dash memory buss. Seems like the breaker is the 2nd or 3rd one from the bottom on the left side of those breakers in the basement.
2. This is the steeep learning curve all of us tinkers have been through. You are doing fine just don't be afraid to ask.
3. On that buss it seems like you need to look for breaker 51, 52 or 53 but these are auto reset.
3a. Your choice is to either take off the wire on on the breaker listed in #3 or trip the one in the basement that feeds this buss in #1
4. Yes
Mike
On edit: The IT department head run down an electronic print B-2197 that should be close for your coach and it list breaker #52 feeds the 2 AC units with 12vdc. BUT double check your prints to be sure.
Mike
I was fiddling around with the wires( phone cables ) again and now the thermostat does not light up or function at all,nor either AC. I did find the schematic 2197 and found breaker 52 on it which says AC and steps so I will try that tomorrow
So.... If that works to light up the thermostat is there any value in trying the 5 button upgrade kit I have?? This is frustrating the crap out of me and I really don't want or spend big coach bucks at arc repair shop!!!
Peter,
With you fiddling with the wire and losing power, it sure sounds like you have a bad spot in the phone cable or cable end. Until you find out why you are losing power to the Tstat there ain't no need to change out to another Tstat. There is no need to pay a shop to learn on your coach so YOU keep at this and don't get over flustered. Walk away, take a break, and go back at this looking at it from a different angle.
Mike
Mike,
You might also test for 12VDC in the thermostat's phone plug. Try all combinations of the contacts though usually the red and black are for 12 volts.
The plastic dividers usually are in the way, so you no need paper clips or straight pins held against the meter probes to touch the phone plug contacts.
It also is quite possible that the off-on switch is corroded and/or too loose inside. This is what I repair or replace along with replacing the worn out push buttons.
Jim Frerichs
2002 U320 42'
3zero8four4zero51five4
Mike/Jim/Turbojack
I found the #52 breaker at the front dash, disconnected the 2 wires attached, waited a few minutes and then re connected. No joy. I purchased 4 new 4 pin telephone couplers and installed them
The front phone cable from the thermostat is silver in Color coming out of the thermostat. There are two silver cables in the front AC which are joined together by a coupler. There are two black phone cables joined by a coupler at the front ac as well. I did notice one of the black cables has the the little "click" tab off of it but I pushed it in securely. The pic attached show the fron ac with all the cables attached. The right silver cable was detached which is how the unit fired up the front ac as stated before. I have sprayed all the connectors with contact cleaner. The second photo shows the rear ac with one silver cable coupled with a black cable. The second coupler has a black cable plugged into it by nothing connected to the other side
LOST for words here......
I guess I should ask...would an AC RV specialist be able to diagnose the issues quickly?? Any idea of costs. I am in Canada so the prices of course will differ.
Additional pics of the rear ac and thermostat
You are doing great!!!!
Very good chance you are going to pay someone to learn how the system works and how to trouble shoot the problem. I would say about 20% chance you will find someone that can do a better job then you are doing.
Now with that said.
Go up on the roof, Remove the covers and then remove the metal (I believe) cover to get access to the circuit boards. First check and make sure everything is plugged in tight. Look the circuit board over and verify that there are no burnt spots on the boards. (front and rear AC's While you are up there, take pictures like you have done. I am thinking the phone wires are plugged into the circuit boards. While you are looking at the board you may be able to see where the 12V DC is connected to them and verify that the rear board has 12 volts.
Turbojack
Now that you mention it, I was up on the roof and looking at the rear ac with the cover off. The two black phone connectors are connected on the circuit board and I noticed one of the connectors was a little loose from the circuit. I did not think too much about it but maybe maybe that is the reason?? But does that explain the no power at the thermostat? Almost tempted to install the 5 button thermostat and both new circuit boards ( which was my intention anyway) to see if that remedies the issue. Laughed about what you said about the cost of having it done. Again, thanks for all the suggestions...like I said this is brand new scary territory for me!
Peter,
I had a similar issue like you a couple of years ago. Had both A/C's on High Cold and plugged in to a 30 amp circuit ( I know, brain lapse). Everything was fine for a short while, then both A/C's quit working. I could unplug the 5 button T-Stat and reset and all would work again, for about a minute, then go dead. I assumed I fried the T-Stat, so replaced it. Worked for about 5 minutes, then all dead again.
I got on the roof and removed the covers and unplugged the circuit boards, then reset, same result, all good for about 5 minutes, then dead.
Got a new circuit board for the front A/C, hooked it all up................Been working great for 3 years now !
If I remember correctly, paid about $80 for the T-Stat and $110 for the circuit board. My plan was to replace parts one a time until it worked. For $200 and a little !@&%! language, I got it working. Figure I was still way ahead money wise than calling a service, plus I can be pretty stubborn sometimes. :headwall:
Something else, if I believe that those circuits boards have some fuses on them. May be worth a look.
Beginning to think I should start by changing to the 5 button thermostat and 2 new circuit boards and go from there
Just a WAG but are you sure the couplers are okay? I've never seen this type of coupler.
The coupler are standard phone couplers. There were the exact ones on there before the issues started
The Dometic couplers are not the same as a phone connector. They look alike but internally are different. You will need to check the 3 amp fuse in the upper circuit board in both ac's. I have fixed these issues by using contact cleaner on the cable ends and also inside the couplers. The Dometic cables are data not phone cables so they are not interchangeable. You may have blown the 3 amp fuses in the upper circuit boards. Put everything back together as original and start from there. You might have to look up how to reboot the thermostat so that it will recognize all parts of the system. You should be able to find how to do that on the internet.
Remind me please.. to work on the ac on the roof, disconnect the #52 connections for 12 v on the passenger side dash , disconnect shore power and switch ac breakers off at foot of bed??? Correct or am I missing something?
Peter,
If the breakers for the A/C units are off at the foot of the bed you can leave the shore power alone. If you unplug shore power it is just like belt and suspenders so if it makes you more at ease unplug. Yes removing a wire off breaker 52 will kill the 12VDC to the A/C system.
Mike
Absolutely frustrated.
Unplugged the 15 amp shore power...disconnected 12volt at passenger dash ( was tied with step cover)...turned off both ac breaker at foot of bed.
Then went on roof and installed the new circuit boards for both AC unit which came with the 5 button thermostat as a complete upgrade kit. This part did not go too bad
Then went into coach and started the generator ( I only have 15 amp shore power and wanted to fire up both AC's if possible )
I then re connected the 12 volt power and put both AC 120 breakers back on
I then plugged in the 5 button thermostat and went through the initial reset required.
NOTHING....no power to the thermostat at all. I unplugged the thermostat and replugged it..nothing
Frustrated I went on the roof and noticed the front AC fuse had blown. Tried to replace it and it kept blowing. Went down and disconnected the 12v power and replaced the fuse. It held. Then I connected the 12 volt power and it blew again!!
Don't have a clue.... Any idea why the fuse keeps blowing when the 12 volt is connected??? I am sure the circuit boards were done correctly and the data cables were put back to the same configuration as I stated at the beginning of the post ( see pics)
Idea???? Help!!!
PS. I even unplugged the thermostat at at the wall and the fuse blew when I connected 12 volt....I have not changed any wiring at all to cause a short!
I know this blurb is long, but I will ask something else. Put the dip switches on circuit boards to: front ac. heat strip on furnace on.
Rear ac. Zone 2 on. Furnace on. Are these settings correct??
Just phoned Dometic....what a waste of time....
Peter,
You have a direct short to ground. Sure sounds like you either have a broken wire in the communication cable or a bad connector shorting to ground. When you take the 12vdc away and the fuse holds there is no flow of electricity so the fuse holds. When you reconnect the 12vdc the electricity starts to flow (amps) and with a direct short it will be more amps than the fuse is rated. The hard thing is finding the short and fixing, this may also correct the intermittent loss of power to Tstat that you have been having.
Mike
Ok so if I substitute the data cable from the wall thermostat with another run through the coach to the front AC will that be an indicator?
Peter,
The short answer is Yes. That is how I would troubleshoot a bad cable.
Now you need to be sure that the wires in the plugs are the same as the OEM ones as sometimes they are different depending on the application. Wire could be set up like wire 1, 2, 3, 4 goes to 1, 2, 3, 4 on the other end, Or does the wires swap to 1, 3, 2, 4 on the other end?
Mike
I sure hope turboj will chime in on this as he has a lot better ability to explain what I am trying to convey on the wiring of the communication cable ends.
Mike
So correct me if I am wrong but the power to the front AC comes from the data cable that is connected to the thermostat and runs to the front AC right? So if the front AC fuse keeps blowing it HAS to be that cable right?
Unfortunately I am spent for the day and won't be able to check/diagnose anything till tomorrow, but ANY help will be appreciated ( and maybe save me tons of dollars)
The 12 volts in the front A/C does not come from the data cable. 12 volts from the front A/C powers the thermostat.
The front AC board has 12 v going to it from the coach. This 12 volts powers from the coach is what powers the board and the thermostat as craneman said above. The 12 volt power from the front control board powers the rear AC circuit board via the phone wire. You could have both breakers turned off at the bed for the AC's and the thermostat would still have power to it since it is coming form the coach 12 volt system.
Go to page 27 and it shows you how it is wired up.
http://myrvworks.com/wp-content/uploads/2019/04/Duo-Therm-4-Button-CCC-Diagnostics-Service-Manual.pdf
Disconnect both data cables. Reinstall fuse. repower up with 12 volts. Does fuse hold or blow? If it did not blow try plugging in 1 data cable at a time to see if fuse blows. If it blows while attaching one of the data cables the problem could be the data cable has short.
Look at the data cable receptacles (not the data cable, ends on board or thermostat). Check and make sure the little pins did not get crossed and is touching one of the other pins.
Turbojack
I will give your suggestion a shot tomorrow. This cat and mouse game is certainly mildly entertaining but definitely frustrating!!
Need to look on the board and also the couplings to make sure a pin is not misaligned and are crossed..
Home Depot has a RJ11 tester where you can test your cables to make sure they are good
http://www.homedepot.com/p/Klein-Tools-LAN-Explorer-Data-Cable-Tester-with-Remote-VDV526-100/309925931?source=shoppingads&locale=en-US&&mtc=Shopping-RM-F_DYNM-G-D27-027_011_TOOLS_ACC-KLEIN_TOOLS-NA-NA-SMART-NA-RMP-MK495473330_9016864402_FY22_1927_RM2&cm_mmc=Shopping-RM-F_DYNM-G-D27-027_011_TOOLS_ACC-KLEIN_TOOLS-NA-NA-SMART-NA-RMP-MK495473330_9016864402_FY22_1927_RM2-71700000083602792-58700007073070013-92700063677501837&gclid=Cj0KCQjwpImTBhCmARIsAKr58czrOddIVjR-RFXClTpxrPpUU0TFKKg3iRweQL4H129F7thVAFhOfKkaAitAEALw_wcB&gclsrc=aw.ds
If you get the tester you could test the cable from the circuit board all the way to the thermostat or from circuit board to circuit board. That way you would also be testing the couplings to make sure that is not your problem.
So I have an update
I installed the 5 button thermostat and the 2 new circuit boards
As I said before that resulted in fuses blowing on the front AC unit. I followed what was suggested (including buying the meter to check cables) I did check some cables and got some continuity between some and re booted the thermostat and it came on. My dip switches are set in the Ac units as follows:
Ac 1. Heat strip. On. Furnace on. All other switches off
AC 2. Heat strip on. Furnace on. Zone 2 on. All other switches off
I got the front AC on ( exactly how I started this topic and the new thermostat shows zone 1 now but NO zone 2. Front AC and furnace etc works but no rear AC. I checked fuse in rear AC. It was good. New circuit board was wired correctly. Cables look ok.
Frustrated again!!
Is the rear circuit board dip switches correct?? Any suggestions why the 5 button won't recognize zone 2 or power up the AC??
Suggestions??? Pic one. Front ac
Pic 2 rear ac
Pic 3. Thermostat
Zone one circuit board
Also look at the tiny 4 springs in the black jacks. If any are bent or out of their dividers, that would allow for very poor connections.
Jim
2002 U420 42'
Do you have heat strips? If not then that should be turned off. # 2 zone switch should be turned on and furnace on. It is a communication problem between the front ac and the rear ac take a data cable direct from the front to the rear bypassing the cable in the roof and then reboot the thermostat not the correct term but it is to let the thermostat reset and recognize both ac's. I am pretty sure it is in the communication.