Lance 1181 and Honeywell Thermostat

[wannabegone]

Hello, I'm sure the answer to my question is here somewhere but I have been unable to find the information. I am attempting to install a Honeywell RTHL2510C 7 day programmable thermostat in my 2008 Lance 1181. I installed a 5-2 programmable Honeywell thermostat in my travel trailer that works great. The Lance currently has the Atwood digital thermostat that is hard to get the selector in the right mode. After seeing the price of the Atwood I decided that if the Honeywell is good enough for the house and the TT its good enough for for the TC.

I pulled the Atwood thermostat off the wall and inspected the wiring, over all everything looked normal other than 2 extra wires my TT didn't have. Red, White, Green, Yellow, small Blue and a large Blue/White. The small blue wire was easily solved, the a\c has a 2 speed blower motor the Green is the high speed and the small Blue is the low speed. I decided to hook up the thermostat leaving the large Blue/Wire disconnected. Once hooked up the A/C operated normally, I used the Green high speed lead. The heat does not work.

I pulled out the Lance manual and found the Atwood wiring diagram. I found according to the Atwood wiring diagram the White wire is the system 12v ground and the Blue/White wire listed as a ground to the furnace. so being the risk taker I am I removed the White wire and installed the Blue/White wire in it's place, still no furnace. Next I surfed the internet to try and find out what each terminal of the Honeywell does. I came up with was Red-power, Yellow-cooling, White-heat, Green-fan and Blue-usually always common. So again the daredevil I am I hooked the White to the B terminal, no dice the heat still doesn't work.

At this point due to my wild and crazy diagnostics I reinstalled the Atwood thermostat, luckily all works properly A/C and heat. I brought my good volt meter home from work and if I have time on Friday after the turkey wears off I'm going to see what each terminal on each thermostat does. That is unless someone here has the fix that'll allow me to quickly move on to my next project.....
Thanks in advance

[wannabegone]

I swapped the thermostats out and did a few test. Again the a/c unit is operating normally with the Honeywell thermostat but still no heat. I have White/12DCV (-) to B, Green/fan high to G, Yellow/compressor to Y and Red/12DCV (+) to R. With the B/W wire disconnected I connected the DVM to 12VDC+ and checked the White wire for 12VDC- DVM 13.3V with the heat off, when the heat is on 6.47V, heat off 13.3V. I checked other system grounds and the voltage is 13.3V heat on or off. I am using a separate circuit from the furnace or a/c to connect the + side of the meter to. I tested the W/heat terminal with the heat off, 0V heat on 6.47V it is the same in gas or electric heat mode I also checked the O terminal 0V when the heat is on and 13.3V when off and the NOT USED terminal which was 0V heat on or off. I connected the Blue/White wire to the W terminal and repeated the test, heat off 13.3V on 6.47V but the voltage is steady. I tested resistance between terminal B and W of the Honeywell 0L heat off 5.87M ohms when on. The Atwood terminal 1 and 8 0L with heat off or on.

I'm not sure exactly what is happening when the Atwood thermostat is telling the furnace to come on but it looks like the Honeywell doesn't donit the same way.

[wannabegone]

So looking atvthe information I've got in front on me it looks like the a/c unit is a RVP Products 9000 series and the furnace is a Atwood 8500-IV 2 stage series furnace.

According to the wiring diagram I found on the furnace paper work the furnace should have a + and - to or from the thermostat and + and - 12VDC from the battery or converter. With the rain so far today I have not pulled the exterior furnace cover. So far I have found the Blue/White wire to be grounded all of the time and terminal 8 of the thermostat where the Blue/White wire connects to be some type of resistor or something. When the B/W wire is connected and the system off DVM connected between 12+ and terminal 8 of the thermostat 13.3V with the thermostat switched to heat and the furnace commanded the voltage is continually fluctuating from 3V to 8V. With the B/W wire disconnected when off DVM connected between 12+ and terminal 8 1.46V on 2.56V.

The Honeywell thermostat is going to be a little more difficult to get this information due to the design but hopeful I'll be able to post that shortly.

[wannabegone]

westend this crossed my mind but since the White is listed in the wiring diagram as a system ground, negative circuit on the 12v system, and the Blue/White as a furnace ground I don't this that will work either, beside I touched the wires together and nothing happened. I don't remember if I had the switch to heat or not though.

Chris I'm going to check the A/C and Furnace models when I get out to the TC, since it is raining looks like it'll be sooner than expected. According to Lance's wiring diagram there are no connection between the a/c unit and the furnace. Actually the only diagram I have of the 2 shows the Blue/White wire as (-) to the thermostat and a Blue wire (+) to nowhere stating "not used" meaning I need to find the furnace model to find a diagram as to how it is wired became in a 12v system it either + or - are missing nothing iis work. I'm also hoping the DVM will ahead some light on how the thermostats work.

[Chris_Bryant]

What air conditioner is this controlling? Coleman switches +12 volt, and the furnace is directly controlled by the thermostat, analog DuoTherm switches grounds, and the furnace is hooked to the air conditioner.

[westend]

It sounds to me like you need both the blue/white wire and the white wire connected to ground. You state that you were connecting one of those at a time to ground.