Hello, my name is Tom Brintzenhofe. I'm a certified master mechanic from Reading, Pennsylvania. Today, we're going to talk about how to diagnose a cooling system problem. Most vehicles have one problem or another when it comes to cooling system either generating too much heat, overheating, not generating enough heat and runnin' cold all the time. Most problems you'll find when it comes to the cooling system is either dead summer, when it's real hot outside they tend to overheat; problems in the winter, obviously you have no heat. The first thing I'll talk about real quick is the thermostat. A lot of majority of the heating and cooling problems come from this thermostat. If it ever sticks closed the vehicle will overheat. If it sticks open a lot of times it won't generate any heat. And the thermostat sits right back here; up beside this housing. The other problem you might might find is a radiator. If a radiator gets somewhat blocked from corrosion, pieces of rust and stuff from inside the engine gets blocked up inside here; again, it will overheat. Another problem you might have is you won't have any heat on the inside. Engine's runnin' a good temperature; it's not overheating, not running cold, and again, you have no heat on the inside. The first thing to do is after it's been started and warmed up to a good temperature check these two hoses. You have an in in hose and an out hose to your heater core. On this jeep it's real simple; the next one here on the top. Put your hands on em' as you're running. Please keep your hands away from the front of the engine. That tends to hurt if you get your hands caught in there. But these two hoses right here should be relatively the same temperature goin' in, goin' out. One's going to be extremely hot, so be careful when you touch it. The other one should be slightly warmer, not not too much, but slightly warmer. If they're not chances are you got a blocked heater core. If you got one hot goin' in, and the other one comin' out still cold it's a blocked heater core. A lot of times you can flush em' out so you don't have to take the whole dash apart to change it. Other issue you might have is it's overheating too much. Sometimes you'll have a problem with the water pump. The fins break off inside it. Unfortunately, I don't have one to show ya'. And fins break off; they don't move enough antifreeze inside the motor to cool it off, so again, you have an overheating problem. The cooling problems on a on a vehicle are relatively pretty easy to diagnose. You either have, like I said before, either it overheats, or it doesn't generate enough heat. And what I've explained to you in in this short clip is it's real easy to diagnose. You just follow them few few small steps, and it'll be a walk in the park for ya'.