This all started this winter. Have a '92 5.9 cummins turbo intercooled 2WD RAM. I've changed thermostat,changed radiator, changed fan clutch, checked temp. to heatercore. I am wondering about the intercooler.

I am getting very low heat on highway, temp. gauge is always low. In traffic I get heat. Do you think it is caused by the intercooler? What is the function of the intercooler? This winter is the first time I have had this problem. The motor has 300k miles on it. Mileage is still good.

Anyone have any ideas? Thank you for reading, its cold up in RI/MA right now.

Hot air from the turbo flows through tubes inside the intercooler. The turbo air transfers heat to the tubes, warming the tubes and cooling the turbo air. Outside air (or water) passes over the tubes and between fins that are attached to the tubes. Heat is transferred from the hot tubes and fins to the cool outside air. This heats the outside air while cooling the tubes. This is how the turbo air is cooled down. Heat goes from the turbo air to the tubes to the outside air. Think of it as a radiator, just an air-cooled in the case of our trucks. However, the intercooler should not affect your cab heat, as the radiator heating and cooling should be completely seperate of the intercooler system. You said you checked heat to the heatercore, what about flow??? Do you have any old heater hoses that might be clogged up, misformed, or kinked? Water-pump??? You say the temps in your area are cold, below normal??? How far is your drive? I'm guessing that you haven't likely moved, or changed jobs and that the weather is not drastically different than it was last year, so I know why you are questioning the truck. I am just throwing questions out there.