AC unit will not shut off

[Ontherun]

I have a 2003 Holiday Rambler outfitted with the Dometic 57915 AC units I replaced the front unit in 2014 and it cools perfectly. But once the cabin temperature reaches a selected temp and the thermostat should be satisfied, it will not turn off, even if I run it up to 90 degree. My unit has 2 units so I have swapped out both the thermostat and the AC control board but neither of these items provided a fix. Any suggestions? Thanx

[joshuajim]

You've had this unit for a considerable time, so it's not a newbie factor. Did you perhaps switch the fan to ON vs AUTO and just the fan keeps running? Did you determine if the unit keeps cooling after it reaches temp or just circulating air?

[Ontherun]

Thank you for responding. Once the AC unit comes on, it continues in the cooling stage until I manually turn it off. I can turn the ac off and the on/auto fan and the Hi/Low fan operate as they should. I can have the temp in the cabin down to 75 and turn the thermostat to 85 and it will not turn off. I have swapped out the thermostat and the control board but it has had zero affect.

[ga80486]

If you push the temp button, what does the thermostat think the temp is?