Recent Posts

1

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!

2

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

3

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.

4

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

5

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. 

6

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

7

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

8

Technical Support / Dometic AC and aqua hot heat problem

« Last post by Adam Hicklin on September 11, 2024, 02:04:28 PM »

Hoping for some insight.  Coach sat for about 6 months.  Went to fire up the AC and couldn’t change the zone (zone indicator was not visible) on the Dometic 4 button thermostat.  Other indicators were visible and could be cycled through but AC or heat would not come on.  4 button tstat is problematic so sent it out to be repaired.  Repair tech said when he hooked it up, it seemed to work fine, although he couldn’t figure out why it had 3 zones with a 2 AC system.  Explained the Aqua Hot heating but he didn’t quite understand. He changed the buttons anyway.  Got it back and now it will run zone 1 both heat and AC but the zone indicator still is not visible and it won’t cycle through the other zones.  I’ve checked all fuses although there must be another board for Zone 3 (heat only zone) somewhere.  I can’t figure out how and where that is connected to tstat. Front AC has 2 communication wires hooked in the ports, rear has one, and of course there is the wire that hooks up the tstat.  Aqua Hot is working on the electric side, but not diesel. Diesel side is completely dead.  No humming, buzzing or burner fan  activation. Completely dead.  When the coach was parked, all was working perfectly.  Can’t help but think it’s all related somehow.  Thanks in advance. 

9

Technical Support / Re: Master List of Exterior and Interior Lights for LED Conversions

« Last post by Steve Huber Co-Admin on September 07, 2024, 01:02:22 PM »

Devin,
The majority of owners who upgraded to LEDs removed the existing bulbs and found a replacement on Amazon, etc. Due to the wide variety of available LEDs and the advancement in their design over the years since their introduction, there is probably no standardization or master list by coach model. I converted my 3 coaches to complete LED (except for head & tail lamps) and used differing units on each except for the overhead puck lights (see my ad on the FOR SALE board). That said, there is information on what LEDs members used in various applications available on the Forum. It can be found by doing a Search for LEDs or the specific application/location you are interested in.
Steve

10

Technical Support / Master List of Exterior and Interior Lights for LED Conversions

« Last post by Devin Ginther on September 05, 2024, 05:57:13 PM »

Greetings,

I'm fairly new to the group and hope to be a contributor on the technical side of things.   As an engineer, I'm always into finding better solutions and working around problems.  Been working on cars, trucks, motorcycles, boats and woodworking my entire life so fairly handy.  Plus, we own the Texas Urban Sawmill down here and do quite a bit of very high-end custom furniture work and installs.   So addressing any type of interior woodwork is a piece of cake.   

We recently brought back our 1999 Marquis Jasper from Florida.  Basically owned by a single owner its entire life with a long list of maintenance records.  So I have no major "repair" work other than located a few potential leaks and eventually replacing the slide seals.   

Right now, I'm trying to do a complete LED conversation across both the interior and exterior lighting.   The previous owner, addressed probably 80% of the interior lights already.   So my immediate focus is all the exterior lighting.  I'm also redoing all the lap seams which includes re-sealing all the rear upper red running lights so it is a roof and exterior lighting effort.       

Does anyone know of a reference document or thread(s) that discuss all the exterior lights?   I'm not sure when the headlights and rear lights changed but I would like to create an excel sheet that is easy for people to reference.   

I'm good on the front low & head beams (1A1 and 2A1 enclosure type).   

1) I'm having a hard time identifying the side docking lights.  The exposed light physically measures 5.5" long x 3.25" tall.  I have found the Grote Mini LED work lights (#63610) but this includes the cover plate.  This weekend I will try to pull out the docking lights to see if I can find an original part #.   Thought I would ask here 1st. 

https://www.grote.com/white-light/work-lighting/trilliant-mini-led-whitelight-work-lights/63610/

2) Are new lenses or enclosures available for our rear turn and brake lights?   

3) Are new lenses or enclosures available for the front left & right amber turn signals?   Again, I'm hoping to convert them to more modern LEDs with enclosures that might be a better cosmetic match for the front 1A1 and 2A1 LED headlights that I'm retrofitting.

4) Fog lights.  I've measured the recessed molded enclosure on the front bumper.   Looks like 7-1/2" wide x 4-3/4" tall is the absolute maximum size to retrofit LED fog lights.   If anyone has done this and has suggested or references to their replacement fog lights, much appreciate if you can provide.   

End of day, I love the big rigs that are all LED-d out on the highways.  Not to mention the added safety factor of being highly visible and having front beams that REALLY provide excellent visibility.   Oh and I'm definitely adding relays to the Hi and Low beam circuits to ensure that see the full 12V.   

I'm putting all of this in a master LED spread sheet that I will share the club.   Take me a few more weeks to compile everything as I go from light to light.....