Phantom A/C - Montana Owners Club

gjetzen · 06-02-2014, 01:08 AM

Good morning Montana Nation! I have an older Montana (2005) and am having a problem with the A/C. Yesterday I decided to do some spring cleaning so I plugged in the shore line and opened it up and went about my cleaning. It was a cool morning so I opened up some windows. The remote thermostat said it was 71 degrees inside. When I was finished I just left the trailer open and went inside my house. A few hours later about 3pm I thought that I heard a fan running and went to check where the noise was coming from and discovered that the fan for the A/C unit was running. Thinking that I must have bumped the manual override switch I went inside the trailer to turn it off, but what I found was weird. Nothing was turned on! I grabbed the remote to try to turn it off, no response from remote. I tried the manual override no response there either, so I hit the reset button on the remote and that is when I noticed the temp, it read 99 degrees. It didn't feel like 99 inside the trailer but I guess it could have been. When I hit the reset on the remote it started to respond The manual control would at least beep but that was about it still no other response so I turned the circuit off. I came back later in the day and turned the circuit back on the fan started to run, grabbed the remote hit the on/off button and this time the A/C compressor turned on and the green light on the manual control lit up. The A/C cooled the interior down pretty fast and the compressor cycled off but the fan stayed running, so I turned the circuit off again. This is where I'm at this morning. The A/C unit is a Dometic duo-therm with a wall mounted manual override switch and a hand held remote. It seems to me that there was a lot of complaints about this system and that the main controller inside the unit was the culprit. I seem to also remember that there was a thread on this site about how to diagnose and bypass this controller and wire a house thermostat in. Any help up can give would be greatly appreciated. I thank everyone in advance for your help.

racerjoe · 06-02-2014, 01:42 AM

you are right, if it is not on manual to keep the fan running, the remote system has probably taken over!! These were nightmares to say the least. They would do anything they wanted to do. Ours was the furnace,sometimes it would not shut down without pulling the fuses. Duotherm did make a replacement for these,you would need to get the control box that is inside the filter area and a new thermostat. It is a wired system, all wiring is there,just a replacement. works well. I don't think you can change out just the t-stat without replacing the control unit also. Get your model and serial number off off the air conditioner,pull down filter and the numbers will be in there, contact duotherm to see about replacement parts.

capn chris · 06-02-2014, 03:57 AM

On my '05, the remote had a little door/compartment on the lower part of the remote that popped open to set for fan, cooling, heat, etc. symbols. Have you checked there to see if the fan setting may have been selected? Just an idea.

gjetzen · 06-02-2014, 06:15 AM

capn chris unit is turned off. Symbols are displayed for time, temp fan speed and mode. Remote and manual override not responding. A/c fan runs all by itself.

gjetzen · 06-02-2014, 06:20 AM

Need to hear from OZZ. I think he was the original thread poster.

rgn · 06-02-2014, 04:27 PM

i HAVE A 2005 329 5 RK MONTANA . MY AC AND REMOTE STOPPED WORKING.I HAD TO RE PLACE THE REMOTE AND CIRCUIE BOARD WITH A NEW STYLE BECAUSE YOU COULD NO LONGER GET PARTS. IT WAS NO CHEAP.$$$$$$$$$

**Carl n Susan** · 06-02-2014, 06:55 PM

Here is something I posted back in 2011. If the damn Search function was working this would have been easier to find. The 34 page discussion was not started by Ozz. It started in 2005 and Ozz didn't join the MOC until 2006. I have no idea if the parts are still available.

=========================================

The infamous Remote Control Thermostat installed in the 2005 -2006 model Montanas was a great idea gone wrong. They were notorious for their erratic set points (+/- 10 degrees was common) and their propensity to turn on the heater and the A/C at the same time.

The solution is to replace the Remote Thermostat with the Climate Control Center (CCC) thermostat. Montana and Dometic usually did this for no charge back in the day. I suspect you will have to buy it yourself today for about $200. The change over isn't too difficult.

Everything you ever wanted to know about this topic (Part Numbers, installation instructions, photos, etc.) can be found in by clicking on the following link to a 34 page discussion on this POS.

http://www.montanaowners.com/forums/showthread.php?t=8145

woodtic · 06-03-2014, 03:38 AM

Quote:

quote:Originally posted by Carl n Susan

Here is something I posted back in 2011. If the damn Search function was working this would have been easier to find. The 34 page discussion was not started by Ozz. It started in 2005 and Ozz didn't join the MOC until 2006. I have no idea if the parts are still available.

=========================================

The infamous Remote Control Thermostat installed in the 2005 -2006 model Montanas was a great idea gone wrong. They were notorious for their erratic set points (+/- 10 degrees was common) and their propensity to turn on the heater and the A/C at the same time.

The solution is to replace the Remote Thermostat with the Climate Control Center (CCC) thermostat. Montana and Dometic usually did this for no charge back in the day. I suspect you will have to buy it yourself today for about $200. The change over isn't too difficult.

Everything you ever wanted to know about this topic (Part Numbers, installation instructions, photos, etc.) can be found in by clicking on the following link to a 34 page discussion on this POS.

http://www.montanaowners.com/forums/showthread.php?t=8145

This is a perfect example of why this forum is the best....
Some of the people here are willing to put out that kind of effort and dedication into helping others. Simply outstanding..

I salute you all....

gjetzen · 06-03-2014, 05:19 AM

Carl n Susan Thanks for the info just what I was looking for. I knew that there was a thread for this I just could not find it. OK so here is what I have right now. The A/C fan will not shut off or change speeds. Remote/wall mounted over ride will not control fan but will turn the A/C compressor on. I am assuming that everything is controlled by the module in the A/C unit behind the filter. Called Dometic this morning and was told that there is two ways to repair. Digital single zone thermostat which include a new control board, will control 1 A/C unit and 1 furnace,@ $98.00 or Comfort Control II and a new control board @ $248.00 which will control any combination of 4 heating/cooling units and is rj11 compatible. I can't see me putting on another A/C unit but the Comfort Control II is a plug and play unit. Any suggestions?

gjetzen · 06-03-2014, 05:50 AM

I have one other question. I stated earlier that I "assumed" that the control module is what controls the A/C fan and we all know what the first three letters of assume are. Is there any thing else that I could be missing?

**Carl n Susan** · 06-03-2014, 10:11 AM

Personally, I believe the CCC is overkill for a rig with a single A/C. I would likely go with the $98 digital thermostat. *BUT* only if it can use the existing RJ11 type phone wire and plug. Pulling another control wire to the A/C unit from the thermostat is likely to be an all day (and night) adventure. The CCC was a popular solution, albeit more expensive, because it could use the existing wire.

As for the question, will replacing the thermostat fix the problem? I don't know. I have read where the CCC occasionally looses its brains and you have to pull the fuse from inside and do the magic "reset" dance on the keypad to restore it to normal mode. But that is pretty rare. The CCC will allow you to set different temps for different time periods if that makes a difference.

It is hard to believe you had the infamous remote thermostat for this long. Ours was a problem from day one (in 2005).

gjetzen · 06-03-2014, 11:10 AM

Carl N Susan This is what I know for sure, If I disconnect the rj11 connector at the wall mounted sensor/override switch the fan stays running. If I disconnect the rj11 connector at the control module behind the A/C filter, the fan stays running. This to me would eliminate any problem with the override switch and possible short in the rj11 cable. When I disconnect the big 6 pole white connector at the control module the fan stops. That to me isolates the control module somewhat. I don't know what's between the white connector and the fan. On the $98.00 digital thermostat it is not rj11 compatible but I figure that the rj11 wire was good enough to carry a signal from the old system it should be good enough for the new one. The rj11 cable is 4 individual color coded wires inside a sheath, there is enough extra cable on each end (about 2 feet) that I can cut off 6-8 inches and save the ends in case I have to go back to a rj11 style wiring set up. But I am torn because we have been spending a lot of time in Florida in the fall and was talking about a second A/C unit. But the trailer is almost 10 years old and I guess we could go for the less expensive A/C unit with the controls on the air distribution panel. Thanks again for all your help and advise.

**Carl n Susan** · 06-03-2014, 05:41 PM

The addition of another A/C to a 2005 and using a CCC to control it, will involve installing another temperature sensor in the bedroom plus control wires to the second A/C. Montana didn't anticipate using a CCC in 2005 and the wiring isn't there. Not to say it couldn't be done. But everyone I know who added a second A/C in the bedroom just use the controls on the unit itself.

gjetzen · 06-08-2014, 01:22 AM

Update: Purchased a new A/C controller kit online from Dyer RV parts on Wednesday, it arrived on Saturday. I purchased a Dometic # 3313189.015, it was $84.00. This kit is for a single zone climate control w/o heat strip or heat pump meaning it will handle 2 devices, 1 A/C unit and 1 furnace. It includes a digital thermostat, control module, freeze control probe and some assorted installation hardware. While Dometic claims that this is the direct replacement for the infamous infared digital remote control for a single zone it is wired totally different. All of the wiring connectors except 1 are different and it is not rj11 compatible for thermostat wiring.

Setting the old and new controllers side by side you will need to study the wiring diagrams of each to see what is different about the two, what is the same and then there is the issue of the rj11. It took me about 1/2 hour to figure it all out. I cut the connectors off of the rj11 (both ends) and reused that wiring bundle for the thermostat wiring. you will use 3 out of the 4 wires for that. It took about another 45 minutes to wire everything together. I was told by Dometic that this controller package would come with installation instructions, it did not and there is nothing online from Dometic either. I guess they figure you are supposed to be smarter than a plastic box. There is however instruction for thermostat set up and operation.

Now comes the moment of truth, I hook up the battery and plug in the shore line go inside the trailer flip the switch for the breaker and.....silence. No A/C fan running, nothing smoking YEAH! I read the operating manual and hit the go button set the temp and let the A/C have at it. Everything cycles fine unit cools off. Now for the furnace. Set the thermostat high 81 degrees let it cycle through. Everything seen to work as Dometic claimed it would.

Now it's Sunday and I going out and try it all over again and set up the thermostat to my specs instead of the factory specs. I'm excited!

racerjoe · 06-10-2014, 11:33 AM

The dometic help people are very good if there is a start up problem. when I switched mine over they helped me right on the phone to clear up wiring issues. Have had no issues since change over

gjetzen · 06-10-2014, 01:52 PM

racerjoe, have had no problems with the operation of the new controller and thermostat. The only thing that I was a little concerned about was the fact that the wiring from the old controller to the new controller was different. There was supposed to be a installation guide/manual to aide in installing the new controller, but mine didn't come with one. I did call Dometic but it was late afternoon on a Saturday and no one was available to answer my questions and there is no documentation online for this controller and thermostat kit. It took me about 1/2 hour of studying both wiring diagrams of the new and old controller to figure out what I needed to do. All is fine. Sunday I just fine tuned the thermostat to my temp setting instead of the factory preset.

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