Both air conditioners won’t come on

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Both air conditioners won’t come on

July 27, 2021, 10:06:16 pm

Help!! So in the hottest of days in BC I plugged the coach into 50 amp and everything is powered up. Went to turn on the air conditioner and the panel showed as the pic shows and the air conditioners do not come on. What I see on the panel is that the zone 1 and zone 2 indicators on the comfort control are not showing. Are there fuses that I am missing or what should I be looking at. ??

Re: Both air conditioners won’t come on

Reply #1 – July 27, 2021, 10:18:13 pm

Peter I'm not an AC expert but one of mine would not come on and I replaced the large capacitor that is in the AC electrical box on the roof
Been working fine since then
Chris

Re: Both air conditioners won’t come on

Reply #2 – July 27, 2021, 10:36:51 pm

I believe there is a small fuse, 5 amp I think, maybe smaller, under the AC cover. Check that. Power to the thermostat comes from the AC.

Re: Both air conditioners won’t come on

Reply #3 – July 27, 2021, 10:49:24 pm

Roger
You mean on the roof or pulling the inside cover off? As you can see the zone 1 and zone 2 does not come up on the duotherm although the rest of the info is there

Re: Both air conditioners won’t come on

Reply #4 – July 27, 2021, 10:53:38 pm

Peter, no picture. I recall the fuse was up on the roof under the cover. There is a circuit board which might be under a metal cover. Be sure to open the circuit breaker before sticking your fingers in there. It has been a long time since I was in there and the ACs have been replaced.

Re: Both air conditioners won’t come on

Reply #5 – July 27, 2021, 10:55:22 pm

Pic of duotherm. Not no zone listed that was at bottom

Re: Both air conditioners won’t come on

Reply #6 – July 27, 2021, 11:03:03 pm

Lights are on, may not be fuses. Communication cables look like a 6 wire phone line. Plug and in-plug. These are accessible from the inside.

Re: Both air conditioners won’t come on

Reply #7 – July 27, 2021, 11:08:39 pm

Are these 6 wire unit in the duotherm. Not sure

Re: Both air conditioners won’t come on

Reply #8 – July 27, 2021, 11:12:44 pm

Ok tried unplug and reply tele cable. No joy

Re: Both air conditioners won’t come on

Reply #9 – July 27, 2021, 11:39:13 pm

Quote from: Chris m lang – July 27, 2021, 10:18:13 pm

Peter I'm not an AC expert but one of mine would not come on and I replaced the large capacitor that is in the AC electrical box on the roof
Been working fine since then
Chris

Chris by your prior post I had pre purchased both capacitors for both my unit. Loaded them out before I could install and last week forward unit stopped starting and blowing hot. It did still display zone one and two. Replaced all four capacitors in units and ran fine since.
By the way got the opportunity to relearn a old lesson capacitors hold a charge. I figured they had not been ran for 12 hours they should be discharged. To my surprised the bad unit capacitor bit me pretty hard. So always short out capacitors with a jumper lead before handing ⚡️
Scott

Re: Both air conditioners won’t come on

Reply #10 – July 28, 2021, 12:03:05 am

Chris
Still a bit confused as the duotherm lights up show the temp and actually in-checking only goes from fan to cool on the duotherm. It does not change to furnace at all. What next?? Again maybe I should add that I tried the Aqua hot and it does not come either. Hell of a way to a start a trip

Re: Both air conditioners won’t come on

Reply #11 – July 28, 2021, 07:17:06 am

I would try the following, may need a reset:

Try cleaning the contacts. You may have to reset the control after re-installing.

Here is the reset sequence for the 4 button t-stat:

If AC or heat is non functional, confirm the following:
Data Cable is correctly wired.
Fuse is good in power module board.
Confirm 12VDC.
Verify DIP switch settings.

1. Turn control ON to insure annunciator data and light are present.
2. Press MODE switch to activate light.
3. Simultaneously press the BOTTOM TWO BUTTONS (temp up and temp down) and HOLD.
4. While holding these two buttons, PRESS the MODE button once and release.
5. Release the two held buttons.
6. Depress the MODE button again.
7. At this time, the light should extinguish and the mode should indicate OFF. If not, repeat steps 2 through 6.
8. Retest system insuring that all functions are present and operational.
9. If system is still non-functional, remove Comfort Control Center and install a new control.

Re: Both air conditioners won’t come on

Reply #12 – July 28, 2021, 07:30:38 am

I reported the same problem a while back.
I asked where the power to the control came from, as it would not light up.
I checked the fuse on the unit, and it seemed good.
We were in Mexico, at the time, and I had no clue of how to proceed.
I disconnected the phone wires at the front ac unit, and the control lit up again, and work fine...
until now
How do you check for 12 vdc?
How do you verify dip settings ?
and what do the capacitors look like? How do you know they are bad? How do you discharge them? Where do you purchase them?
Right now we have no heat or ac.
Gotta fix it

Re: Both air conditioners won’t come on

Reply #13 – July 28, 2021, 07:57:17 am

Memory is not as good as it use to be but I think the AC get 12v from the coach. Then the AC sends the 12v to the thermostat. I had a problem once and I had to go and find the 12V circuit breaker that was in the compartment under a cover and pull the wire off and then put back on in order to get the thermostats to start working correctly. I am not sure if I had tried the salesman switch then or not or even knew about the salesman switch then.

Re: Both air conditioners won’t come on

Reply #14 – July 28, 2021, 09:06:51 am

Glenn I got the capacitors off Amazon
Read the voltage and microfarrid ( spelling)
On capacitor to order they were about $10 each
Sorry can't help more we are remote and not good internet
Chris

Re: Both air conditioners won’t come on

Reply #15 – July 28, 2021, 09:24:22 am

https://www.supplyhouse.com/Hartland-Controls-CAP-20-10-440R-20-10-MFD-Round-Dual-Motor-Run-Capacitor-370-440V
https://www.supplyhouse.com/MARS-11963-108-130-MFD-Round-Start-Capacitor-330V
This was for 2001 units. They are a bit larger and higher voltage, that is okay.
To short out take and jumper leads and jump across connections.
The two wire just plugs in either way, not marked
The 20-10 cap has three connections the C goes to common/neutral white wires, the fan to fan and the others to the last post.
Short out new capacitors before handling. They are located under the main cap and on the passenger coach right there is a 6"x6" panel with two 5/16 head screws. Caps are mounted on a panel that also has two 5/16 screws holding it down and the two capacitors are mounted with a strap with two more screws. Note position, large capacitor towards rear. Power disconnected and I recommend coach powered down. IMO should be changed every 5-10 years in the desert heat. #1 cause of ac not working. Cheaper than a service call.
Scott

Re: Both air conditioners won’t come on

Reply #16 – July 29, 2021, 01:12:50 am

Thanks for all the responses. I tried the reset cleaning the contacts and can not find any fuse to check. Can anyone advise where it may be. It is NOT in the AC unit on the roof. Tried to find a replacement 4 button replacement here in western Canada but they do not make a 4 button unit any more. Any one have one? The five button conversion would not be here for 10 days to two weeks. Doesn't help with the hat now!
If I do have install the five button conversion, is it an easy DYI project?

Re: Both air conditioners won’t come on

Reply #17 – July 29, 2021, 11:00:59 am

if you are changing to the 5 button thermostat, each unit will need a replacement
circuit board. the info is on the dometic site.

Re: Both air conditioners won’t come on

Reply #18 – July 29, 2021, 11:07:36 am

If you can get Dometic to give you the information you can jumper wires at the thermostat to get the air to run just not gong to turn off without disconnecting the wires.

Re: Both air conditioners won’t come on

Reply #19 – July 29, 2021, 11:30:18 am

If you think it's the controller, another option may be to replace it with an aftermarket unit. Here's the one I've been eyeing...

EasyTouch RV™ Thermostat – Micro-Air, Inc.

They make a direct replacement for the 4 button controller that just plugs in.

Re: Both air conditioners won’t come on

Reply #20 – July 29, 2021, 12:14:54 pm

Your Canadian location might be an issue, but perhaps check with Jim Frerichs as a repair option... Dometic 4 button thermostat repair

Re: Both air conditioners won’t come on

Reply #21 – July 29, 2021, 03:34:51 pm

So I experimented and started disconnecting wires etc and found that if I disconnected the phone cable connecting the two AC units ( I think...) the main AC runs, just not the bedroom AC. A temporary fix I m sure and I don't know if the AC will run all the time but it does cool us until we can get it looked at

Re: Both air conditioners won’t come on

Reply #22 – July 29, 2021, 03:49:35 pm

Peter, Good job of detective work.

Maybe get a 6 wire phone cable with connectors, it should be easy to find, make sure the ends are oriented the same as the original. Flat cables usually have a ridge on one side for orientation. Connect the two ACs, if they work it is most likely a connector at one end of the OEM cable or the other or the cable itself.

If there is enough slack cut off the old plugs and crimp on new ones, one end at a time and reconnect. Pay close attention to the orientation of the cable and the plug, one end is likely different from the other. If it doesn't fix it then a new cable is needed.

You may be able to use the old flat cable to pull a stout string through and then use that to pull the new 6 wire cable without a connector and then connect a new connector at the pulled end.

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