Product review (5 stars): Freezer cool but fridge warm? Look at these parts. UPS reporting lousy
I have a cheap second refrigerator in my garage; it's branded "Costco by Whirlpool" and built in 1999 in Mexico.
Recently the refrigerator compartment wasn't cooling... spoiled milk was the first clue. This was in spite of the fact that the freezer compartment was fine.
I knew that if the compressor was bad it probably wouldn't be worth repairing this old fridge BUT it probably was OK since the freezer was working. Given the age of the refrigerator I was reluctant to call out a repairman when the meter is at $75-100 when they first show up. So I Googled "Whirlpool refrigerator not cooling" to see if I could get any hint as to whether or not it was liable to be a big problem.

MUCH to my surprise I found a lot of really useful information including several very helpful UTube tutorials. These videos provided trouble-shooting tips and detailed disassembly instructions.... once I opened up the freezer compartment (not at all difficult) it was clear from the hidden ice buildup that the defrost cycle wasn't working and that the ice was blocking cold air from the refrigerator compartment.

Several of these videos pointed to the automatic defrost system as the likely culprit and specifically to the bi-metal defrost thermostat.  This thermostat is a simple on-off switch designed to keep the defrost heater from getting too warm and defrosting the food in the freezer compartment.  One video even showed a test procedure to verify whether the defrost thermostat was faulty (involves a multi-meter and a glass of ice water, but a AA battery and a flashlight bulb would have worked). Sure enough it looked bad (and failed the test) so I went to the local supply houses to find one. They had generics in stock but those lack the clip-on feature. The delay for the clip-on part was four days and the cost was $35.... I could have gotten it just as fast and much cheaper through Amazon&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Whirlpool-2321799-Defrost-Bimetal-for-Refrigerator/dp/B004XLEH38/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Whirlpool 2321799 Defrost Bimetal for Refrigerator</a>. The only "skill" required to install the thermostat was stripping the wires and applying wire nuts and electricians' tape (see UTube if you want detailed how-to help with that).

While I was in there I noticed the fan motor was wobbly and somewhat sticky and thus seemed likely to fail soon. The fan motor is $65 from my local suppliers so I ordered this guy from Amazon. It was easy to install with my newly-found expertise at removing the freezer parts and fit perfectly... probably a 15-minute chore to replace.  It works without wobbling and is very quiet and smooth turning. Everything good except my worrying.
Why worrying? The vendor delivered the part to UPS within 24 hours of my order but the UPS tracking system said it was going to take 16 DAYS to get here.... from CA to WA!! I kept checking and the UPS system kept reporting 16 days. It actually showed up in 5 days (three working days, which is normal UPS Ground from California), so it was all about faulty UPS reporting not any actual service problem.  But if you were waiting for it to repair your main refrigerator it sure could cause some stress.