Wash, peel and slice your vegetables. The carrots will be very soft so leave them in large pieces.
Select the sauté setting on the Instant Pot and add the oil. When hot, add the slices of onion, smashed garlic, thyme and salt and pepper. After a minute to two, add in the chopped celery.
Sauté until onions start to brown and everything is golden. This step give fantastic flavor and is worth the time if you have it!
Turn Instant Pot off and add the water to the pot. Carefully set in the trivet/basket into the Instant Pot.
Make sure all packaging and anything tucked inside the chicken has been removed. Place the chicken on the trivet, breast side up.
Sprinkle the top of the chicken with reserved TBs of diced onions, 1 sprig of thyme leaves and additional salt and pepper. Place the carrots around the chicken. Twist on the locking lid and close the steam valve. I cooked this 4 pound chicken for 24 minutes. Set manual, high pressure for 24 mins. Twist on the locking lid and close the steam valve. I cooked this 4 pound chicken for 24 minutes. Set manual, high pressure for 24 mins.
NOTE: If you have a larger or smaller chicken, the rule of thumb is 5.5-6 mins per pound.
When the pot beeps and the time is up, allow the pot to natural pressure release for an additional 25 minutes. This will help lock in the moisture and finish the cook time. Carefully remove the chicken and let cool for a little bit before cutting into it.