My Mom refuses to use her AC and its too hot for that.

Acclimation plays a role in heat consequences too. Our family has been in construction for several generations - not only outside in high temperature but working in high temperatures, even on roofs. People who work in this environment adjust to increasing temperatures gradually as weather warms. Except for increased water intake and more smelly work clothes, there's no noticeable impact on productivity until temperatures get high enough to really start impacting the body's ability to cool itself, usually 95+ with high humidity. Humidity is actually a bigger problem than just temperature because humidity defeats sweating to cool the body faster than rising temperatures, which is why fans or a good breeze can really help the body cope.

So older people who like warmer temperature and do not use AC also acclimate to rising summer temperatures gradually and do not seem distressed by temperatures in the upper 80s and even lower 90s. My grandparents never had AC although they did live in a house designed for airflow and cross ventilation. The only time they consented to using any AC at all was during a record heat wave where temperatures were reaching 100 degrees each afternoon and overnight temps were staying in the upper 70s. My uncle purchased a couple of large window AC units and lowered the house temperature into the low 80s during the day and about 75 overnight. Any lower and my grandparents complained it was just too cold.

Until the local authorities start issuing warnings about dangerous heat, your mother will probably cope with the heat. If she has heart or lung problems her tolerance for heat may be lower and she may actually need AC; however, she may not want AC to lower the temperature as much as we would like. I suggest trying to see if she would tolerate AC better if you set the thermostat for a higher temp, maybe 80-86? Along with the dryer air an AC provides that should be low enough to escape heat related health problems.

Is it possible your mother is concerned about the higher electric bill from running the AC? The higher temperature setting (where the AC runs less) might also help with that concern.

It's probably because it makes her too cold, but have you asked her if she's worried about the cost to her electric bill? Also, a dehumidifier can make a room more comfortable without making it feel cold. Cost about $100-$175ish.

Have you asked her doctor for advice about this?

Ah, the rain forest effect.... that is how it felt when walking into my parents house. They were in their 90's. And my Mom would have on long pants, knit top, sweater, knee high socks and shoes, and a scarf around her neck. And there sat Dad in his walking shorts and nothing else. Poor Dad, he would just sweat it out.

If everyone is under the same roof, set the temp to a comfortable level, and close off the vents in the rooms where the parent(s) spend most of their time, leaving the other rooms to be cool.

If she has any arthritis then the cold air cold be painful. I would adjust all of the vents so they are not blowing on her.

My mom thinks 85° is the perfect temperature and she l8ves where it can be 120°. I can't visit her home for more than a few minutes because I cook, she doesn't even break a sweat.

I would look into some good electrolyte tablets, they have more impact then a sugar filled drink and replace many more essential nutrients. She can continue the gatorade if she enjoys it, our bodies flush out the excess.

My mother lived in Independent Living and refused to use her AC. She had high blood pressure and congestive heart failure. I told her that not using the AC was dangerous; her doctor told her the same thing. (She also lived in the NE). She had a stroke (in the summer, no idea if in any way related to the heat; but over the years, we found that she was more often I'll in the hot months). Once she was moved to a nursing home, the AC was not optional and she wore sweaters year round.

I have same problem - my mother refused to get a car with air conditioning until she was about 50! The only thing that has worked is to set the air conditioner to come on when it gets about 75 inside. I'm sitting there sweating and they think it feels fine. You just have to turn it down to where it will keep them from having heat exhaustion! I also had to put the plug into a clear locked box to keep them from yanking the cord out. Electrician said that would really shorten the life of the unit.

We had the same problem with my mom (also many years ago with my Grandmother). We live in middle GA & outside temps go into the mid-high 90’s. Despite our arguing, I must admit they never got dehydrated or had a heat stroke.

When mom became immobile she had a lock box installed over the thermostat & wore they key in a pouch around her neck so her caregivers could not adjust the temp.. Which was set on 85 just for them because I told her she had to “provide safe working conditions” for them.

As we age, our skin thins. She is probably right she doesn't need it because she is cold. Is she in a facility? It is not at all uncommon to see many elderly dressed with sweaters even on the hottest days. They, just plain and simple, get cold easily.