I noticed that the heat in my truck was not warming up the cabin, the driver side was heating to 70 degrees and the passenger side was 90 degrees. So what i did was take the 2 heater hoses off the heater core under the hood at the firewall and backflushed it. I used a Thexton heater core backflush tool that connects to a garden hose, it works great. Then i installed the 2 hoses back to the heater core reversed so the coolant is flowing backwards through the heater core. Now i am getting 150 degrees on the drivers side and 160 degrees on the passenger side. Works great i am warm again.