Digital Thermostat Installation

[socalroger]

I recently purchased a 2012 Cougar Xlite and am in the process of replacing the Coleman-Mach anolog thermostat with a Honeywell digital unit. I have a specific question about the A/C cooling fan connection:

There is a black and green wire coming from the trailer thermostat wire. If both these wires are connected to the green terminal on the Honeywell, the fan appears to run on high. If either the black or green is connected to the HW, the fan seems to run on low (there doesn't seem to be too much difference).

Question - should both the green and black wires be connected to the HW for high?
If I want to run fan on low (by adding an extra switch) does it matter if either the green or black only is connected?

Thanks,

Roger K.

[bobbecky]

Was the old thermostat used for just the A/C or did it control both A/C and heat? Does the thermostat wiring have six wires? What are the colors of the wires? And one other question, does the new thermostat control the same things as the old one did? (high/low fan, heat. cool) and why are you replacing the thermostat?

[socalroger]

The old analog thermostat was used for both heating and cooling and I'm installing a digital because it controls temps plus/minus one degree rather than the uncomfortable 4 degree swings of analog technology.

The new installation is working fine except I want to add an extra switch for hi/low fan since the Honeywell only has one fan speed. All wires are connected and accounted for other than the correct use of the green and black ac fan wires. See my original post.

[bobbecky]

If the black and green wires are for the two speed fan, then it doesn't matter. You would probably have a single wire from the switch to the new thermostat, and then have the green and black wires connected to the other side of the switch, so in one direction, the green is connected, and the other direction the black is connected. I think this would be called a single pole-double throw switch.