How do you convince an elderly person (who is always cold) to turn on air conditioning in summer?

I have been through this and would notice it when I would visit my Mother. The elderly are much colder than we are.
As I read your question, I see that it is her house. So, you are probably out of luck. No one likes to be cold. There are stand alone room A/Cs and if you pay the difference in the electric bill, that might work. (It is 113 degrees, here, today.)

I try to remember how I would like to be treated if the shoe is ever on the other foot. I don't understand old age but older people do understand those younger than they are, after all, they have been there already. I don't really believe aging people really want others to be uncomfortable, so they must really be cold and that is more miserable than younger people being hot.

I'm not that young and I am menopausal so I have hot flashes while I'm the homes of those more aged than me, (I', 60.) and I understand that being so hot is hard. I help aging people by cleaning their homes so I am constantly moving and get very, very warm. My solution is to take a small towel and get it wet with cold water, wring it out and wrap it around my neck. I'm sure there are cool wraps that you can purchase that do the trick better, or ice packs that you can drape around your neck that cool you down without harming your skin. But for a quick immediate solution the towel trick workes well on the spot.

I have so much respect for the aged that they often do offer to turn down the heat for me out of returned respect and I always refuse. I suffer for them and believe they deserve no less than that. And I just keep getting more respect for that, too. It's amazing, but it works. Just get that towel out, get it wet and wrap it around your neck. Your clothes get damp, too, which also cools you off. And those folks love you for it. Nothing beats being loved.

I had my mother's doctor tell her what the ac thermostat should be set to. I could never live with my mother. If she's "nursing home material" according to her doctors, consider what that means. She needs 3 shifts of caregivers. One person cannot do that job, dear.

I disagree that we're supposed to suffer for our elders in this manner...I see no logic in suffering to the point of getting sick and having to go to the hospital just because my mother wants the temperature to be in to the 80's inside in the summer time(or any time for that matter),,You're foolish to put yourself through that misery..My mother stays cold all the time.she's 92 years old and has been living with me since march of 2016.I put extra blankets over her and even bring out the winter jacket if necessary but I won't continue to sweat profusely in my own apartment for the sake of my mother's comfort when I can keep her warm by covering her and her wearing thick c0lothing.TO SUFFER TO THE POINT OF 24/7 SUFFERING absurd and you're slowly going to ,make yourself sick iby remaining so hot so much of the time.this is not healthy!!! you understand?

This is one of the worst problems to me. I can never understand why older people feel that everyone else has to roast so that they don't have to use a throw or dress warmer. It makes me madder than anything else, because if I can't sleep or work because I'm too hot, I can't stay here. The only thing I have found that works is pointing out that I have the thermostat set on 80. (This keeps the house cooler, because our thermostat is off.) 80 degrees sounds very reasonable, so my mother doesn't protest much.

The thermostat wars can be terrible. Sometimes she is too hot when I'm comfortable, so I end up freezing. Or some mornings she turns on the heat when it is already warm. I am firm with her, though, about not having the house too hot. I wouldn't be able to stay if she insisted, because it would make me sick to be hot all the time.

its hard because its her house. unless you are the one paying the electric bill not much you can do. Now at my house the thermostat is set at 72 and stays there because i live in south texas where its 94 today with 100% humidity and a heat index of 102 . i am not going to sweat for anyone. i get hot i get grouchy. there is a blanket on her chair and a jacket next to her chair. there is also a nice comfy chair outside on the front porch where she can sweat to death if she wants. the best thing i ever bought for this house is the new electronic thermostat. she wont touch it because she dosent know how to use. it. if not, set the tempature to where you want and Take the thermostat off the wall so she cant change it. i had to do that with my son he hated the air conditioner.

The "thermostat wars" are a problem at my mother's house, which is one of the many reasons I don't live with her. When I was living there, I bought a very nice window air conditioner for my bedroom, and it's still there for when I stay overnight. When I'm there, I spend as much time in that room (or outside the house) as possible. When I cook for her, I crank up the central air, and she has the choice to either bundle up or go hungry. And yes it is annoying, dripping sweat while I'm changing her bedding, for example. And my mother is not nearly as bad as many others in terms of cold sensitivity. One idea is this: if you can do it, close the air vents in the room she's sitting in (I assume she sits most of the time in the same spot like my mother does) and open them in the rest of the house, keeping as many door shut as possible so the chill doesn't enter her space. And reverse in winter - open windows in the other rooms to let the cold air in when she has the heat cranked up high.

I'm not sure how old you are. Are you her caretaker? Does she rely on you to be there so that she can live in her home? If so, then I would approach it differently than if she is capable of living on her own. Because, if you are an adult, you could move out. So, you pretty much have to play by her rules and preferences.

I think I would discuss it with her and see if you can come to a middle ground. First buy digital thermometers for the rooms you go into the most. See if some of the rooms are cooler. Try to arrange it so that most of the AC cool air is reaching you. As someone else said, close the vents to her rooms. AND I would consider a standing portable AC unit. I can be moved from room to room. It has a hose that can be placed in any window. They are affordable too.

During the night, you could use the portable AC. I would get the average for electric bills from the past and agree to pay for any mount that is greater. It shouldn't be that much more.

If you are going to be around for the future to help care for your grandmother, I would think she would want to make the house an enjoyable place for you to be.

Another tip I learned. If you are hot and she won't turn on AC. Place a large tub of ice in front of a fan. Sit in front of it and it creates a nice cool breeze. At least for a little while.

The nursing home I visit keeps the temp at 74 in the winter and in Summer many residents refuse a window unit until the room hits 80. So try a middle setting, about 77 or just set the unit to de-humidify if it has that option.

The problem is you can't convince I constantly cold person to turn on the AC during summer, I personally would just go turn it on myself if it was dangerously hot in that area. Some people don't realize how dangerously hot an area gets during the summer, and heat stroke claims many lives each summer. Sometimes you just have to take matters into your own and is an override someone who may not be in a position to make very competent decisions when everyone else knows the dangers of summer heat and heat stroke. 

My elderly friend who since died was always cold toward the end due to lack of circulation which was due to lack of exercise. I didn't know how lazy he really was until they put him into a nursing home and took away his power chair and mobility scooter and made him use a walker. We all knew he needed the items but not nearly as bad as he was letting on, he could've gotten by with just a walker much of the time. He always complained of being cold. He kept the AC at a hot setting and having a damaged auto nervous system from childhood, I have an overheating disability where I'm vulnerable to heat illness. Therefore, I just can't be where it's hot so I really didn't have too many options other than to either just leave despite him wanting me there or sneak behind his back and set the thermostat to a slightly cooler setting that was comfortable for us both. After a while he would set it back to the warmer temp, and I had to always have a frozen hot water bottle on me. Of course in a cooler hot area it doesn't stay cold as long as it should. I'm just glad they took away all his control when they put him into a nursing home because the thermostat was controlled by the nursing home where they had central air. That way, when they turn on the AC, you have no control over it and if you're cold, you'll just have to put some layers on or hop on the treadmill and get the blood moving. 

A final thought would be there if you can't be in a hot area, just refuse to be there and the elderly person who wants you there bad enough will somehow find clever ways to accommodate you, if not they won't. Just don't put yourself and your health at risk to please someone else if you know for a fact you're negatively affected by the summer heat