Recent Posts

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Technical Support / Generator not cranking when controlled by Xantrex.

« Last post by Chuck Jackson on Today at 04:31:05 PM »

I’m helping a friend set up his Xantrex SW2512 inverter to perform the auto start for the generator. He has a 2005 Beaver Marquis. The generator starts fine with generator switch on the dash.  You are supposed to be able start the generator using the Xantrex controller either by using the auto start function or the ‘On’ button. Neither of them will start the generator. You can hear the generator fuel pump clicking but it never cranks. There is a relay on the Xantrex inverter used for cranking called RY8. This relay has a green light that does illuminate for a few seconds but then goes out. I’m wondering if the relay is bad? Does the green light illuminate with power to the relay or from the relay to the starter?

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Technical Support / Dometic 4 Button Thermostat Troubleshooting Manual

« Last post by Steve Huber Co-Admin on Today at 04:27:51 PM »

The Dometic 4 Button Thermostat Troubleshooting Manual has been added to Coach Assist in the Heating and A/C section.
Steve

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Technical Support / Re: Dometic AC and aqua hot heat problem

« Last post by Steve Huber Co-Admin on Today at 04:07:08 PM »

Adam,
Bear with me on this; You said the AQH is working on electric. I assume (maybe incorrectly) that by working you mean that the AQH responds to the t'stat settings. If so, the wire (signal) from the t'stat is getting to the AQH and since you have a single t'sat and the AQH uses a single t'stat input for both electric and diesel, it's not clear to me why you are looking for the t'stat wire. The connection between the t'stat and the AQH is working.
The light in the Diesel switch is powered by a signal from the AQH so it may be a bad switch or a problem in the AQH itself. The AQH has separate internal control t'stats that sense the boiler fluid temp for diesel and electric functions. If the diesel t'stat is bad it could result in the symptoms you are reporting. See pg 14 of the service manual.
The zone selection problem sure sounds like either a faulty t’stat or that the dip swiches in the t’stat aren’t set correctly.  I’ll email you the manual for the 4 button t’stat in case you don’t have it. (I’ll also add it to Coach Assist).
Steve

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Technical Support / Re: Dometic AC and aqua hot heat problem

« Last post by Adam Hicklin on Today at 01:47:45 PM »

Thanks Steve and Eric.

My mistake.  It’s the 431/12 AQH.(stupid fat fingers)

Steve, I’ll investigate the switch today. The indicator light by the switch has never come on, even when everything was working fine, so it’s never been a help.  I’ll dive in to the switch today.  But all fuses are good and voltage is good.

Eric, thanks for that.  I have the diagram for the 431/12. I have one thermostat in the coach.  With one comm cable to the back ( much like the old phone, 4 wire cable, which comes from the AC.)  The tstat wires from the AQH don’t run directly to the tstat in the coach.  They have to interface somewhere else.  Maybe on the AC board?  Maybe on some buried circuit board somewhere else? But as Steve said, I can get heat to the zone 1, but zone 1 is where the tstat is stuck.  Can’t change off zone 1.

I’ll keep searching.  Keep the suggestions coming!

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Technical Support / Re: Dometic AC and aqua hot heat problem

« Last post by Eric Maclean on Today at 02:49:59 AM »

Adam
Page 59 in the 1996 Patriot wing diagrams should get you what your looking for.

Eric

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Technical Support / Re: No Crank. C12 Cat

« Last post by Keith Moffett on September 12, 2024, 09:23:21 PM »

Not sure of your starting circuit so I’ll leave that to others.  The RVA company is now part of Brazel’s group in Centralia Wa. (800) 417-4559.
Good luck.

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Technical Support / Re: Dometic AC and aqua hot heat problem

« Last post by Steve Huber Co-Admin on September 12, 2024, 01:58:33 PM »

Adam,
The communication between the Tstat and the AQH is the same for both elect and diesel (Fig 18 in the service manual) so if the AQH responds to the tsat setting on electric, it is getting the signal it needs for diesel also. The owners manual for the 431/12 (no 421/12 listed) lists possible causes for the diesel no start symptom. It breaks it into 2 cases depending if the light in the diesel switch comes on or not when the switch is activated. Low battery voltage (10V) can cause the problem in both cases. It the light comes on there are 2 fuses in the AQH that could also be bad, although you indicated you checked them. I'd also check the switch itself and the connectors listed in the owners manual troubleshooting guide. But before that suggest you verify you are getting 12V at both battery sets and to the AQH, if you haven't done so already.
Steve

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Technical Support / Re: Dometic AC and aqua hot heat problem

« Last post by Adam Hicklin on September 12, 2024, 05:13:33 AM »

AQH model 421/12.  I’ve cleaned every connection on comm cables.  Fuses checked on both AC’s and all AQH fuses.  This model AQH has no fault indicator.  I’ve verified all 4 AQH tstats are good (diesel control tstat). Fluid is topped off. 

Joel, on this vintage coach there are 2 AC’s and 3 heating zones inside the coach, controlled by ONE tstat in living room area.  Basement zone is controlled automatically. I can’t figure out how the thermostat communicates with the AQH and heating system. I can’t find any type of control board like that on the AC units with any kind of comm cable.  But they have to communicate somehow.  I have the service manual for the AQH but that gives no indication on how they all communicate.

Appreciate all input.  Unfortunately, there aren’t many people left that know much of this vintage coach.  I’ve talked to a few local techs, but apparently I’m speaking another language. 

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Technical Support / Re: Dometic AC and aqua hot heat problem

« Last post by Joel Ashley on September 12, 2024, 02:30:08 AM »

Our two 5 button Duo-therms have zone buttons, but each thermostat is in the zone it controls, front and bedroom, so the zone button is functionally of no use that I’ve found.  I can’t use the front tstat to run the bedroom AC or exchanger, and vice versa. 

A 3rd zone represents the basement heater, which has its own automatic thermostat that kicks in if the hydronic heat is on and bay temps drop to around 40F.  I’d surmise that a 3rd zone shown on a living area stat could also be there for long coaches that may optionally have a third roof AC. Regardless, I’ve never been sure why the “zone” button is on coaches with multiple tstats, except that it’s simply a standard tstat used regardless of the number of appliances controlled.

But as to Steve’s query, did you check for fault lamps on the AHot control circuit board in the bay, prior to sending the tstat for service?  Usually a low battery, low coolant, or other malady is cause for the system to not even start the firing process, and a fault lamp will light on the board accordingly.  I fret that your tstat remake may have been unnecessary, esp. if the tech was not aware the device can be used in three AC/three exchanger area rigs; and his “fix” may now befoul normal tstat functions if and when a correct appliance diagnosis is engaged.

Joel

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Technical Support / Re: Dometic AC and aqua hot heat problem

« Last post by Steve Huber Co-Admin on September 11, 2024, 04:45:00 PM »

Adam,
If you haven't, suggest you remove the t'stats and clean the phone wire connections with contact cleaner as the connections can build up resistance if unused for a long period of time. I'd also do the same to the control switch at the bottom of the stat. From what you said, I assume the tech replaced the remaining switches so they should be OK. The AQH issue also sounds like a possible bad connection since the electric side is working but the diesel side is dead. The normal issue with the diesel side not running after a long storage period is fuel gumming up in the fuel filter. However, the fan will normally start running until the control board  senses a no fire situation. I would start by checking the AQH control board to see if there is a fault condition indicator lit or if you are getting a start signal from the diesel switch in the coach interior. I don't know what model AQH you have but access to the service manuals for discontinued and current models is located in the HVAC section of Coach Assist on the BAC website. Access it by clicking the www.beaveramb.org at the top of the page. Then log in on the club website, select Technical, then Coach Assist.
Steve