Forum Discussion

LipschitzWrath's avatar
Jul 11, 2017

AC won't run in "Auto" Positions on Thermostat

I thought I'd ask about another problem I was having with my camper as I wait for my local Yamaha dealer to warranty my parallel cable to see if it fixes my other AC problem...

My 2004 5er has a Coleman Mach 7330D3351 thermostat installed in it. These seem pretty standard but for those unfamiliar, this thermostat has two slide switches.

The first one is the "System" switch. Choices are "Cool", "Fan", "Off", and "Heat". This switch seems to work as intended.

The second switch is the "Fan" switch. It has a "High" and "Low" position for "Auto", and the same "High" and "Low" positions for "On".

The issue I'm having is that it seems like the AC doesn't function in either of the "Auto" positions. I'm not talking about difficulty starting or anything like that, I'm talking about running period.

When the fan switch is in either the high or low "Auto" positions, when I switch the mode to cool, *nothing* happens. However, if I flip the fan switch to either of the "On" positions, the A/C immediately fires up and goes to work.

Am I doing something wrong? Is there some sort of time delay that I'm not letting elapse? What should be happening? My gut tells me that the A/C should immediately fire up, and that's definitely not happening.

Assuming there is a problem, what is this indicative of - thermostat failure?

I have tried to contact Coleman Mach but they won't help a mere civilian, they tell me I must take it to a service center (none within 100 miles).

Any help would be appreciated.

16 Replies

  • LipschitzWrath,

    The auto feature only controls the fan. The selector switch must be set to cool or heat for the auto to work.

    Try this:

    1. move thermostat to extremely high
    2. set switch to auto
    3. set selector to cool
    4. gradually move the thermostat setting down until the air conditioner starts.
  • sch911 wrote:
    In Auto have you tried it with the temperature setpoint all the way to cold (55F)?


    Yes, the temperature slider seems to have no effect.
  • Try hitting the thermostat down by two clicks, one click doesn't do it for some reason. And you might think about installing a digital unit instead....
  • In Auto have you tried it with the temperature setpoint all the way to cold (55F)?
  • I now realize that this thread may have been better served if posted in the "Tech Issues".

    Mods: Feel free to move.