Power went out for an hour and a half how safe is food in refrigerator?

All should be fine even if you wouldn't have turned down the temp. As long as the door on your frig stays shut it will stay cool inside for more than a few hours and even then It would have to stay warm in there to really matter. Enjoy and eat in Peace.

It sound like the fridge was set to too high a temp. when the power went out. If you did not open the fridge during the 90 minute outage the fridge should have retained the temperature it was set at. All of your foods and beverages should be safe to eat and/or cook and eat. Just check your dairy products like milk and cream and be aware they may sour before the expiration dates.

If you don't open the door, a good refrigerator should keep things cold for several hours upon a loss of power.

you are fine, ideal temp is 38 f for fridge , just smell your milk it might go bad before sell by date. and when power was out you did right thing by not opening it

Sounds like you did it right. And, you've put it back up to 40 degrees now? OK