There are only two coolant lines going to the heater. Inlet & outlet. They may be slightly different sizes, so connect them accordingly. If they are the same size then it usually does not matter which is inlet and which is outlet. But ask yourself, why are they disconnected. More than likely the heater core is leaking and needs replacing, so be aware of that and watch for leaks inside the vehicle, passenger side.
It is the relay for the heating and cooling fan
Heating and Air ConditioningNotes Blower Controls
1. The possibility that the setting switch is for blower/ fan or for heating and not cooling in air conditioners that have both heating/cooling system.. 2.The chilling compartment /compression of cooling gas has leaked. 3.The compression is weak to chill the cooling compartment.
need to locate the blower motor on Mercedes 300E 3.0 motor
If you have no blower speeds check the fuses, check the switch and finally check the blower motor.
Blown fuse? Bad blower motor? Bad resistor pack at blower motor? Bad switch?
Most likely is a short in the wiring from your heating/cooling/vent controls to the blower motor, or simply the blower is going bad.
You don't bypass it, you replace it. It doesn't cost that much
Decal/card on the inside of the fuse box cover should have this informaiton.
Answer15 minutes if you know what you are doing, 30 minutes if you don't. See "Related Questions" below for the instructions to replacing the blower motor
If your Pathfinder is over heating then you may have an issue with the coolant. You can try adding more coolant to ensure that your car is no longer over heating. You can also double check to make sure your blower is actually cooling your engine.
It is on the heating unit on the back facing away from the inside of the car. Not an easy place. Service manual tells you to remove the whole unit to get at it. Which means removing the heating and cooling pipes that enter the back of the car under the heating unit and pulling the heating unit out.