Furnace blows air through AC?

Redrider007

Well-known member
2015 bighorn dometic thermostats lcd. When I turn furnace on the air blows out of my ac units in bedroom and living room. Nothing out of floor vents- what am I missing here?
 

danemayer

Well-known member
If the fan is set to high or low, the A/C fan will run continuously. Cycle the thermostat to FAN mode and press the + or - button to change the fan setting to AUTO.

If your living room thermostat is set to FURNACE/HEAT mode, and the thermostat set point is set higher than ambient temp, the furnace blower should start within a few seconds. After about 20 seconds, it should attempt to ignite the burner.

If the furnace blower doesn't run at all, cycle the thermostat to OFF and press the + or - key to see what the ambient temperature is at the thermostat.
 

Redrider007

Well-known member
inside temp is 76- set fan to auto and temp to 90- ac fan stopped running but no furnace running with eather thermostat in bedroom or living room
 

Jim.Allison

Well-known member
Exact same thing happened to me, I followed danemayer's instruction and to my surprise, I can now enjoy heat in my rig and never hear the AC fan.

2015 bighorn dometic thermostats lcd. When I turn furnace on the air blows out of my ac units in bedroom and living room. Nothing out of floor vents- what am I missing here?
 

Randor

Active Member
If the fan is set to high or low, the A/C fan will run continuously. Cycle the thermostat to FAN mode and press the + or - button to change the fan setting to AUTO.

If your living room thermostat is set to FURNACE/HEAT mode, and the thermostat set point is set higher than ambient temp, the furnace blower should start within a few seconds. After about 20 seconds, it should attempt to ignite the burner.

If the furnace blower doesn't run at all, cycle the thermostat to OFF and press the + or - key to see what the ambient temperature is at the thermostat.

Dan - that worked for mine as well as far as shutting off the A/C fan in the living room. My furnace is controlled with the bedroom thermostat.
 

pegmikef

Well-known member
If the fan is set to high or low, the A/C fan will run continuously. Cycle the thermostat to FAN mode and press the + or - button to change the fan setting to AUTO.

This has to be one of the most common omissions on PDIs when dealers are supposedly teaching folks to use their equipment.

Ironically, when I checked in at the KOA in Texas last night the lady saw my Big Horn and said that is what she had been living in for four years. I briefed her on the club and forum and told her if she had any problems or need to know how to do something to check it out . . . you guessed it, after four years her a/c fan runs when her furnace is on. We fixed that!
 
Top