I decided to do the Hunter 42999B conversion on my TT as the Duo-Therm thermostat was like all the others.I have a Dometic Duo-Therm 13,500 roof air, and I THINK an Attwood furnace (if need be I can remove cover to check).Here's what I did:red wire was on Duo-Therm +7.5 terminal, I didn't use ityellow wire was on Duo-Therm cool terminal, to Y on Hunterwhite wire was on Duo-Therm furnace terminal, to W on Hunterblue wire was on Duo-Therm hi fan terminal, temp not usedorange wire was on Duo-Therm fan terminal, to G on Huntergreen wire was on Duo-Therm gnd terminal, to RC on HunterI left the jumper from RC to RW in the HunterAlso, the small switch is set for HGI have the furnace working properly, but when trying A/C all I get is the compressor running, no blower fan. Also, there is no fan when the manual fan position is switched on, either.This seems so simple a conversion, can't believe it's not working right.

Did you add the SPST mini switch? You need it in the system to make the AC fan work correctly. AC fan is normal high speed.

I've run mine without the switch. First on the high fan wire, and then the low fan wire, which I liked better. OP, I don't have the info to help you troubleshoot it, sorry.

ok I gotta ask, why are people changing the stats?

Only need to add a switch if you want low and hi air conditioner fan speed. I run mine on low (orange wire connected) and like it just fine that way.I don't see anything in your post that reflects incorrect wiring. Perhaps your next step should be to check for voltage on the orange wire.Here's a good set of instructions to double check your work: CLICKY FOR HUNTER T-STAT

midnightsadie wrote:ok I gotta ask, why are people changing the stats?Because the analog t-stats over shoot set point by 2-5 degreesThe swap is to a digital t-stat which controls to set point +-1 degreeOP.....I did the swap without using a mini switch but I wired it to use high fan speed (low fan didn't more enough air for me)

Hunter thermostsat conversion problem | Good Sam Community

donn0128
Explorer II
Dec 10, 2013
Did you add the SPST mini switch? You need it in the system to make the AC fan work correctly. AC fan is normal high speed.
Snowman9000
Explorer
Dec 10, 2013
I've run mine without the switch. First on the high fan wire, and then the low fan wire, which I liked better. OP, I don't have the info to help you troubleshoot it, sorry.
midnightsadie
Explorer II
Dec 10, 2013
ok I gotta ask, why are people changing the stats?
Mont_G_J
Explorer
Dec 10, 2013
Only need to add a switch if you want low and hi air conditioner fan speed. I run mine on low (orange wire connected) and like it just fine that way.

I don't see anything in your post that reflects incorrect wiring. Perhaps your next step should be to check for voltage on the orange wire.

Here's a good set of instructions to double check your work: CLICKY FOR HUNTER T-STAT
Old-Biscuit
Explorer III
Dec 11, 2013
midnightsadie wrote:
ok I gotta ask, why are people changing the stats?

Because the analog t-stats over shoot set point by 2-5 degrees
The swap is to a digital t-stat which controls to set point +-1 degree

OP.....
I did the swap without using a mini switch but I wired it to use high fan speed (low fan didn't more enough air for me)
Chris_Bryant
Explorer II
Dec 11, 2013
To the OP- the wiring looks good- try jumping between green and orange to see if you get low fan then. The only oddity is that DuoTherm uses orange to energize the fan and blue to switch between high and low- so even though blue is listed as high fan, you must ground both blue and orange to get high fan.
Keith_Smith
Explorer
Dec 11, 2013
I had the same problem last summer when I replaced my Duotherm thermostat with a Hunter. What I didn't realize at the time was that new thermostats have a built in delay to protect the compressors during situations where powers will go off and right back on( like during a thunderstorm). It takes 2 1/2 to 3 minutes for the AC to be triggered to come on. Originally, I thought I had a bad thermostat when the AC didn't come on. I took the Hunter back to Lowes and got a second one with the same result. I went to the house disgusted and when I came out an hour later the AC was running. I turned it completely off. I resorted to calling Hunter and the tech politely explained this to me. Embarrassingly, it was on page 25 of the manual. I went back to the trailer, turned it back on and waited a few minutes and it powered right up. Worked normal after that.
trailrider
Explorer
Dec 11, 2013
Good point but the OP said he hears the compressor running so he is past the time delay feature.
Chris_Bryant
Explorer II
Dec 11, 2013
Just to clarify, the analog DuoTherm units (no longer available), switch grounds to activate the relays in the rooftop unit. Coleman /RVP units switch +12 volts to activate relays. Also, as I said, the orange wire turns the fan on, the blue toggles between high and low. If you just ground the blue, you will not get any fan operation.
wmoses
Explorer
Dec 12, 2013
midnightsadie wrote:
ok I gotta ask, why are people changing the stats?

When I change mine it will be for two reasons - more precise temperature control and also I want to be able to have it automatically switch down to a night setting to conserve on electricity and to be quieter.