Neither Dometic Duotherm AC is working - 03 HR Endeavor - help!

[baloo]

We purchased this low miles 2003 Holiday Rambler Endeavor 38PST back in December, and never checked the AC due to the winter season, although they supposedly worked. It had been sitting maybe for one year, although it was plugged into house current at the dealership.

It has front and rear Duotherm Dometic 13,500 BTU AC units. (I do not know if they are heat pumps or not -- how do you tell?)

When I went to turn on the AC now that it is summer and we're wanting to start using the MH, the AC units will not turn on. I get an "EE" message on the thermostat. Here is what I have found and done so far -- to no avail:

1) The thermostat reads "EE". When I try to reset per usual instructions, it momentarily flashes "FF", but when the two buttons are released, it goes back to "EE."

2) A mobile technician said it was the thermostat. We replaced the thermostat -- NO CHANGE.

3) There is measurable 12V DC power at both units.

4) There is measurable 110V AC current at both units using the generator (7.5KW).

5) The RJ-11 lines from thermostat to front AC and from front AC to rear AC are all good (per the line tester).

6) Per Dometic 800-number Help Desk, the on-line tech said it was the control boxes on the units. I purchased two new control boxes (BTW, best prices, by far, are on EBay -- $72.50 incl shipping!!). HOWEVER, replacing the control boxes did nothing! The thermostat still reads "EE" even after trying to reset.

WHAT ELSE CAN IT BE??
It has to be something simple, right?
What am I overlooking?
What should I test next?

Can the dip switches somehow be incorrect, or would this not affect at least one of them running?
Can low Freon cause them to not run?

Thanks for any help. Reached frustration saturation point.

[Barlow46]

Let's start with some basic information.
How many thermostats? (sounds like one only from your description of RJ11 lines)
Do the fans run when you turn on "fans only"?
Where did you get your "reset" instructions for the thermostat?
Did you try turning off both your house and chassis battery switches for a few minutes and then turn them back on?
Do you have an inverter with "auto-start" for your generator and if so, did you check to see if the settings on the inverter may be causing the problem?

I would start by turning off all battery switches, inverter switch, thermostat setting "off", disconnect and reconnect all RJ-11 lines and the turn them back on in sequence starting with the battery disconnects. Let us know what you see after trying this.

Edit: I doubt that both units would go bad at the same time and be out of freon. Those are sealed systems and usually go 10 years and more.

[Dr4Film]

Attached are some manuals that may help you determine your problem and the solution.

The first one for the Dometic Penguin Low Profile A/C may tell you how to determine whether you have heat pumps or not.

Good luck with your trouble-shooting.

Dr4Film ----- Richard

[baloo]

Originally Posted by barlow46

let's start with some basic information.
How many thermostats? (sounds like one only from your description of rj11 lines) yes, one -- controls front and rear somehow,

do the fans run when you turn on "fans only"? No -- nothing happens; only the "ee" code on the thermostat.

Where did you get your "reset" instructions for the thermostat? They came with the thermostat, and were the same as reported on this website -- "hold down the first and the fifth buttons while turning on the thermostat.

Did you try turning off both your house and chassis battery switches for a few minutes and then turn them back on? No, i did not do that. Explain the logic?? Remember, i replaced the control boxes as well as the thermostat, so that would seem to equate to a system reset, nyet?

Do you have an inverter with "auto-start" for your generator and if so, did you check to see if the settings on the inverter may be causing the problem?
This may be something, because i do not understand it. How can i check the inverter settings?

I would start by turning off all battery switches, inverter switch, thermostat setting "off", disconnect and reconnect all rj-11 lines and the turn them back on in sequence starting with the battery disconnects. Let us know what you see after trying this.
Will try tomorrow. This truly sounds like mumbo-jumbo to a novice like me, and i'd like to hear the science behind it, just for my own enlightenment. It must have something to do with resetting everything, although i would think that completely replacing the thermostat and the control boards would already have accomplished a system reset. But, in the world of electronics and computers, i'm aware of black magic.

Edit: I doubt that both units would go bad at the same time and be out of freon. Those are sealed systems and usually go 10 years and more.

please see my responses in caps next to your questions. Thanks for your suggestions. Will try the "complete shut down" tomorrow.
Can you tell me something about the dip switches and how they work?

[baloo]

Originally Posted by Dr4Film

Attached are some manuals that may help you determine your problem and the solution.

The first one for the Dometic Penguin Low Profile A/C may tell you how to determine whether you have heat pumps or not.

Good luck with your trouble-shooting.

Dr4Film ----- Richard

Thank you. I will download and read the files tomorrow!

[baloo]

Originally Posted by baloo

please see my responses in caps next to your questions.

Looks like ALL CAPS does not translate on this website....

[Les Stallings]

Originally Posted by Barlow46

Those are sealed systems and usually go 10 years and more.

They certainly don't last that long in my section of the country. I'm happy to get 5 years out of the front or middle air conditioner and lucky to get 6 years out of the rear air conditioner.

[Barlow46]

Originally Posted by baloo

Looks like ALL CAPS does not translate on this website....

I think you can use either bold or underline if you choose.

I will let someone more knowledgeable than me explain the "science" behind a complete reset. When I am troubleshooting something, I always try to start with the basics instead of looking for complicated trouble (if that makes sense). For the last three years of my work career, I worked as a tech specialist (entry level at best) and all the guys that had a lot of experience always asked the simple questions..."is it plugged in?", "Is it turned on"?, etc. Most of the time the answer was a simple reset for whatever reason. Using my TV digital box as an example, I can turn it off and then back on and it does not solve my problem but when I unplug it and it resets....problem solved.

[Barlow46]

Originally Posted by Les Stallings

They certainly don't last that long in my section of the country. I'm happy to get 5 years out of the front or middle air conditioner and lucky to get 6 years out of the rear air conditioner.

Les, I have had units here in FL (all dometic) and have never had one go bad. The oldest I am aware of is/was in my 1996 HR fifth wheel and it is still going strong. I have two in my present 2002 HR fifth wheel and both are running 10 months out of the year as the unit is on a semi-permament lot and both are still going strong. On my present 05 dynasty, all three have worked flawlessly (both heat and a/c). I do change the filters on a regular basis and even in the off months, start them up at least once a month. Guess I am just lucky....going to find me some wood to knock on.

Les, what caused the failure of your units?

[baloo]

Originally Posted by Barlow46

I think you can use either bold or underline if you choose.

I will let someone more knowledgeable than me explain the "science" behind a complete reset. When I am troubleshooting something, I always try to start with the basics instead of looking for complicated trouble (if that makes sense). For the last three years of my work career, I worked as a tech specialist (entry level at best) and all the guys that had a lot of experience always asked the simple questions..."is it plugged in?", "Is it turned on"?, etc. Most of the time the answer was a simple reset for whatever reason. Using my TV digital box as an example, I can turn it off and then back on and it does not solve my problem but when I unplug it and it resets....problem solved.

I'm thinking that you are correct. It must be something very basic and simple, and I will be doing the "duh" smack on the forehead when I find it.

[Barlow46]

Originally Posted by baloo

I'm thinking that you are correct. It must be something very basic and simple, and I will be doing the "duh" smack on the forehead when I find it.

Let's hope so but if not, there are plenty of knowledgeable folks on this website who can guide you through it if it gets complicated.

[Les Stallings]

Originally Posted by Barlow46

Les, what caused the failure of your units?

I believe that inactivity causes a higher rate of failure. I can say for certain that over a dozen of my friends never get 10 years out of roof air conditioners, especially the front one that works hard keeping the windshield area cool.

For rigs that are not used in the heat pump mode in the winter and routinely stored, I'm guessing the seals dry out and results in a loss of refrigerant. Rigs without heat pumps will obviously not be used in the winter. Rigs with AquaHot may not use the heat pumps all that much either.

Since you are in Florida and use your air conditioners almost year around, you may have a better chance at a longer life.

On our 02 Dynasty I had to replace the front AC/HP unit when it was just over 4 years old and the rear AC/Hp unit in another year and a half.

On our 06 Signature I bought it with a bad front AC/HP unit when it was 5 years old. The following year (year 6) the middle AC/HP unit was replaced and this year (year 7) the rear AC/HP was replaced.

The failures on the 02 Dynasty was due to lose of refrigerant and the failures on the 06 Signature were due to heavy electrical surges on unit start-up due to failing compressor motors - probably due to compressor seizing up.

[Gearhead383]

Baloo, your 03 Endeavor had heat pumps as standard equipment from the factory. There was no other option offered.
-Ron

[baloo]

Originally Posted by Gearhead383

Baloo, your 03 Endeavor had heat pumps as standard equipment from the factory. There was no other option offered.
-Ron

Thanks for that information, R&L.