Coleman 7900-6821 New Thermostat Question

[Radar]

Hello Bob:

My system worked fine with an old 2 wire thermostat and the heater works fine with the new lux 1500 thermostat except the AC is not hooked up. I have all of the wire colors at the thermostat and at the Unit but the rest are not hooked up.

My thermostat now has the red and white wire hooked up and a jumper from RH to RC.

When I want my AC on I switch the unit sw. from HEAT to COOL and all is fine just no thermostat.

I hooked the yellow wire in the thermostat - where does the other end of the yellow wire go on the unit?

The compressor is properly connected to the Grey and Yellow wire for the unit and the system blower works when I switch to COOL.

I tried hooking my yellow wire to the other yellow wire... and then I bought a new transformer because I burnt the primary open. Bummer.... It works fine now like it used too.

I just want to set my cooling on a thermostat.

Any ideas... thanks in advance.

Radar

[onyx]

If all you have connected the thermostat is the red and white wire and none of the other wires are connected to the actual furnace then you will have to leave the thermostat on heat and adjust your temp from there. there is a reversing relay in there that prevents the a/c from working in the cool mode and the ac runs when there is a break in the line and turns off when it has a full 24v. I have an idea ill post later on how to correct this but for now this is how its done. sucks.

[onyx]

oh and remember that when you set the temp in the heat mode you need to set your thermostat one degree above where you want it to be to work right.

[Radar]

Hi Onyx... I do have the red and white wires connected to the lux 1500 and to my coleman HVAC. All of the other colors are available but they are not connected. In the Lux 1500 the jumper is installed between the RH and RC terminals. The thermostat controls my heating fine but when I set my 7900-6821 HVAC panel to cool rather than heat my AC and blower run all of the time and my thermostat has noting to do with it I can disconnect it altogether.

Thank folks... just trying to get my AC to work with a thermostat. Do I move my heating wires in the HVAC cabinet to get around this reversing relay?

Radar