Air condioner climbs to 86 degrees

These latest models rely on a cheap part called a thermister. Older ones used a mercury based cold control. A pc board sends a small amount of power through the thermister to judge the temp. As the temp changes the resistance inside the thermister changes. These el cheapo mexican thermisters are a dime a dozen. They have a quick connect. The thermister must be suspended near the coils but not directly on them or temps will not be judged correctly. Since a thermister is less than $10 bucks i would replace that first before calling someone.