Why is fan motor running when car is turned off?

Hi Fred.

I'm not totally sure I understand your question, but I'll take a shot. Are you saying that the engine fan stays on all the time for your car, keeping the radiator cool, and so you're not able to get any heat in the cabin air? Or possibly that the cabin fan is on all the time and you can't get any heat because it's keeping the radiator cool.

unless there is something very odd about your car (or you're living at the south pole), your engine coolant will be plenty warm within a few minutes of starting. If you are doubtful, drive the car for 5 to 10 minutes, stop, turn off the motor, pop the hood, and carefully move your hand close to the radiator. The blower fan helps transfer heat, but that's to move the coolant temp down probably into the 150-200F range.

if you're not getting any cabin heat, I'd have stronger suspicion about the heater core for your air system. In the majority of vehicles, there is a loop of coolant that comes off the back of the engine block, through the fire wall, and up to a U-Bend of pipe. When the heater is off, the coolant is just re-directed back to the engine. As you turn the knob or lever for cabin heat, it'll turn a switching valve to shunt the hot coolant into a heat exchanger/mini-radiator that the cabin air blows past. This system being a mini-radiator is why highways with long uphill grades will advise motorists to turn on their heater full heat, highest fan, when climbing in the summer. it's an additional way to keep the engine from overheating, even if it sucks for people in the vehicle.

Depending on the car, it can be either easy or really involved diagnosing or repairing the heat exchanger. if you go this route, you'll want to make sure that the coolant is circulated through the core thoroughly and that the coolant-system is de-bubbled.

Good Luck!
D

That is pretty much normal, the heater blower fan acts like the radiator does and helps cool the water passing through it by extracting the heat from it. then once the car inside temp warms up it goes back to normal. Nothing to worry about.

sounds like too me that blower moter goen out. winding goen bad. best way to check for this too find the wires leading to the blower motor diconned the wire use volt meter to check ohm in windings. should hve reading of OL. if get readin other than that bsd windingds in it.

This usually indicates that the heater core( a thing that looks and acts like a little radiator) has devoloped a leak. Coolant is circulated through thee heater core(located in that area) when you turn on the heater. The core gets hot and a fan blows airthrough it and out into the cabin. A cracked or corroded core will allow coolant to escape into the heater housing and the fan will force it into the cabin. Hope this helps. Dano

It could be many things. Low coolant, fault thermostat, a blockage in the system, worn or broken water pump impeller, slipping belt on water pump pulley, the cooling fans may not be operating (this could be a faulty temp sensor, fuse, relay, wiring or the fan motor itself).

First look to see if you have a fuse for the blower motor...then you will want to disconnect power to the fan an jump 12 volts to the fan motor to see if it works...if ok, then there is a speed control resistor that sometimes goes bad located on the heater assembly...It is usually right past the fan so the fan can keep it cool and has 4 or more wires on it. if all else ok then last would be the switch inside car

no high speed ? fan motor relay, no slower speeds resister pack.or faulty fan switch.
Check motor with jumper lead from battery,but unplug power lead to motor first. check grounding wire to motor. if motor dont run replace!

you need to check the blower motor resistor.

You need a new heater motor common problem. The heater motor will probably run if you take it out and turn the fan slightly problem is when you put it back together it will not work the next time you turn it on. I thought I had mine fixed only to find it would'nt work after I switched it off and back on.