an elderly friend has an older model White Rodgers thermostat with 2 switches at the top ... the letters are worn off ... we don't know what the switches do ... (left one appears to turn on either cold or hot) ... have no idea what the right one is for. She's 88 years of age, and often has the heat turned on in the middle of summer. Can you advise me how to know the model #, etc.? Thank you.