So, I live in the western suburbs in a newer development, moved in during the fall of 2016. The lawn was sodded back in 2013 when the house was built. From what my neighbors have told me, it's essentially all clay directly beneath the sod. I do my normal fertilizers/milorganite 4 times a year and aerate/over seed each fall. The bare spots and weeds that were present when I moved in have pretty much cleared up and the lawn looks great (minus the dormant stages in the summer), however, it still seems that if I were to take a heavy rake to the lawn I could tear up the sod pretty easily. I'm the type that mows at the same height pretty much all year long (3 inches), so it seems like in the early spring when the grass is starting to green up, it takes awhile longer than the rest of the neighborhood to green up. I've been contemplating renting a dethatcher to take out the thicker dead grass from the prior year, but I'm afraid that if I do that I'll tear the heck out of the sod. Should I drop the mower deck down to a lower setting to mulch up the brown stuff or just be patient with it and let it come in?
Make your last mow in the fall/winter on a low setting and mow low again sometime in the early Spring well before green up on the same low setting. Also, a feeding of nitrogen late in the year like after October can really set your grass to green up early in the Spring.
Can you take a plug or slice out and measure the thatch layer thickness? I wouldn't worry about it if less than 1/2 inch or so. Some thatch isn't a bad thing.
Instead of renting, buy something like this on Amazon. I've used these and been pleasantly surprised. If you even get 2 uses out of it, your are likely ahead of renting.
www.amazon.com/Greenworks-14-Inch-Corded-Dethatcher-27022/dp/B0030BG1HM/ref=sr_1_3?keywords=dethatcher&qid=1556133665&s=gateway&sr=8-3