Digital thermostat

[esty]

good news...it is running...twisting the green and red together runs the fan on HI...twisting red (+) & white runs fan speed on LO

combine green yellow and red (+) and fan and compressor runs and the ac cools very nicely

the blue wire (-) must go to the ground bus on the charger/converter...now to try the thermostat

we can't run the ac very long because we're doing what we're doing with an 12 ga extension cord, stretched out to the max...when the compressors rests and starts back up, it's flipping the breaker that we have the extension cord plug'd into

thanks again for all the help

[rockfordroo]

Sounds good. You're almost there!

FYI: There's not a lot of difference between lo speed and hi speed Some people like them on low because they are a BIT quieter at night. HOWEVER, during hi humidity conditions, there's a greater chance the AC can freeze up if you're running it on the lo speed. There's a sensor that's supposed to shut off the compressor if it starts to freeze up, but some folks have had problems with that sensor shifting or falling off the fins.

SO: If you decide to use the low speed and have any freezing problems, you should go back to high speed and check the sensor position.

[Coneyguy]

This is just a thought is the AC grounded the way it's supposed to be.?

[rockfordroo]

Originally Posted by Coneyguy

This is just a thought is the AC grounded the way it's supposed to be.?

Did you read post 41? They got it working.

Or are you addressing the breaker tripping?

[Coneyguy]

I missed it, sorry.

[esty]

we got the thermostat on the wall today...we connected it to the HI speed fan...neither of us can tell any difference in noise or air movement between HI and LO fan so, for the reason you stated above we'll leave it on HI until we craft the toggle switch mod

either we didn't give it enough time or it doesn't work on AUTO...turn it to ON and it works, blows and cools as expected...is it just a matter of allowing the t-stat to adjust to the temps before it comes on or is another wire needed on another terminal in the t-stat

[rockfordroo]

In AUTO the fan should turn on when the compressor starts and turn off when the compressor stops. So if it runs in ON, but not in AUTO with the compressor, that sounds like a t-stat problem.

[MacGumbo]

I had my refrigerator out and the original DuoTherm thermostat was on the other side of the "wall" so I decided this was a good time to replace it.

I purchased the Honeywell Pro 3000 Non-Programmable Digital Thermostat from Amazon. I got that one because it has a back light.

Since I was going to use batteries and would have to pull the face off to replace them I reinforced the wall behind with a furring strip. At this time I am only going to run the A/C on low fan so I will not be adding a switch.

The process went quite easy and the A/C is working perfectly.

I will attach pics later.

[MacGumbo]

These are the pics from my previous post...

Pic 1 is the wiring from the old DuoTherm thermostat.
Pic 2 is the new thermostat.
Pic 3 is the insulation board behind the thermostat.
Pic 4 is the wiring of the new thermostat.
W- white Y- yellow G- brown Rc- green (jumped to R)
Note: The red wire is no longer used

[CUTiger80]

Originally Posted by dea49

These are the pics from my previous post...

Pic 1 is the wiring from the old DuoTherm thermostat.
Pic 2 is the new thermostat.
Pic 3 is the insulation board behind the thermostat.
Pic 4 is the wiring of the new thermostat.
W- white Y- yellow G- brown Rc- green (jumped to R)
Note: The red wire is no longer used

dea49, thanks for this post. I have the same setup as you on my 2008 FR Surveyor. I purchased the same thermostat and could not get it to work. I thought that I had a faulty thermostat and sent it back to Amazon. The problem for me was that I connected the red (+7.5V) wire to the R terminal on the Honeywell. After putting everything back as originally installed (with the old Dometic analog t-stat), I measured the voltage on all of the terminals. The COOL (yellow), FUR (white) and HI FAN (blue) all had +12 VDC on them which I thought was odd. By connecting the GND (green) (or common) to the R terminal on the Honeywell t-stat, it was basically working in reverse from most systems. Instead of each system (A/C, Furnace, Fan) looking for +12 VDC to power them, the Dometic system is looking for the COMMON since the +12 VDC is already there. I'm going to have to reorder the t-stat from Amazon and try this again now that you have cleared things up for me. I would be interested in adding the HI/LOW fan switch since there is considerable difference between the noise and the air movement between the two on my unit. Have you considered installing this fan switch?

[MacGumbo]

Originally Posted by CUTiger80

I would be interested in adding the HI/LOW fan switch since there is considerable difference between the noise and the air movement between the two on my unit. Have you considered installing this fan switch?

I did but we run on low all the time because it is quieter. Once I redesigned the airflow ducts from the A/C, sealed the air leaks in the ducts from the tank vents, I get more air out of the system on low than it ever did on high before.

Here is a link to a youtube video adding the fan control switch.

link

[CUTiger80]

So how exactly did you redesign the ductwork? Are yours not all tucked up above the ceiling? (I'm obviously referring to the A/C ducts, not the heat.) I would be interested in knowing more since the ducts at either end of my RV offer very little air flow on the low fan speed setting.
The rear of my unit also includes 2 opposing slide outs and the heat distribution back there is poor as well. The previous owner put in a separate thermostatically controlled receptacle for a small space heater that is plugged directly into the campground pedestal.

[MacGumbo]

Well for starters I accidentally found out that the manufacturer had vented the black and grey tanks right through the left side A/C ducts. My TT has two channels running through the roof down each side to which the manufacturer cuts out holes to place vents into. Anyway, A/C air was pushing down through the holes around the vent pipes all the way out the bottom on top of both tanks. I could feel the cool air rushing out when I reached on top of the tank. That is cool air that is not going to my vents and cooling the inside. I removed the vent caps completely and using expansion foam sealed around the pipe at the bottom of the duct and then at the top before reinstalling the vent caps.

Next while trying to find a leak around the A/C itself I found that the discharge air was being directed directly to the ducts by sheer pressure. The air was buffeting flatly against the aluminum frame and styrofoam insulation creating a large buildup of turbulence. I took the same expansion foam and filled in the whole area at the beginning of the ducts, including filling the hollow aluminum frame. After curing, I took a long straight knife and cut through the cured expansion foam to the open ducts being sure to cut them at angles to assist in a more streamline airflow. In doing so the angled cuts in the foam redirected the air flow smoothly into the ducts.

I now have so much air flowing through all the vents that it cools the whole camper in mere minutes.

I took a couple of pics but without dropping the whole bottom this was the best I could get.

Pic 1 - I covered all metal. Including the support along the top to fix a leak that you can't see because of the foam.
Pic 2 - If you look to the left behind the screw that used to be styrofoam that came out several more inches from the left. I cut it away and slanted it back into the duct.

Sorry I don't have better pics of the actual work.

[CUTiger80]

WOW!! That's amazing that you would have thought to look for those issues. I guess I need to take down the bottom of the A/C unit just to see what is going on. Also may be worthwhile to pull the individual diffusers out to see how well they are sealed to the duct.
Thanks for the info and for posting the photos.

[MacGumbo]

Take your phone or digital camera and take a pic in both directions up in the vent hole. You should be able to see end to end. When I took one I could see the black vent pipe cutting through mine.

[MacGumbo]

Here is a pic looking down the duct. You can see to the left the vent pipe cutting through and the foam I used to seal it. You can also see a 12v wire cutting right through the duct as well. The manufacturer doesn't seem to care anything about doing a professional job.

You can see in the second pic that they cut right into the duct for a ceiling light. Cold air blows out all through the fixture as it is located less than a foot from the A/C unit. If they would have put it 1 inch further to the right the A/C duct would be intact and there would be no air loss.

[CUTiger80]

Thanks for the additional information and the photos. When I get the camper back home, I will check this out on mine to see if I have any obstructions in the duct work.
I did install the Honeywell thermostat this weekend using your wiring suggestions and it worked perfectly. I think that I will hold off on installing the hi/lo fan switch to see if I really need it. Thanks so much for the help!

[bikendan]

Originally Posted by CUTiger80

Thanks for the additional information and the photos. When I get the camper back home, I will check this out on mine to see if I have any obstructions in the duct work.
I did install the Honeywell thermostat this weekend using your wiring suggestions and it worked perfectly. I think that I will hold off on installing the hi/lo fan switch to see if I really need it. Thanks so much for the help!

I have a Honeywell and i never installed the hi/lo switch since I wired it for high only.
Never needed the low setting and the a/c runs better on high.

[CUTiger80]

Dan,
I did just the opposite. I wired mine for the low setting since that is the one that we use the most. The only time that I ever used the high setting in the past was when the trailer had been sitting in the sun for a long time and it was very hot inside. I would leave the system fan on high for about 15 minutes and then turn it down to low for the remainder of the time we were camping.

[gmann32]

Ya know! I wired in the hi-lo switch and can't tell the difference!