I have a 2003 Crown Victoria. Within the last year, I changed blower fan resistor (or Blower fan control module) and repaired the Electronic Climate Control Module (the thing inside the cabin that controls A/C, heat, defrost and fan speed). Today, while I was driving, the blower fan came on high and woud not stop. The weather was mild, so I did not have the A/C or heat on at the time. I tried pressing various buttons to make it stop, but it was running at high and wouldn’t stop. The only way to make it stop was to turn off the engine. When I turn the engine back on, the blower fan was on high again.
What could possibly be wrong with the car? I recently changed the blower fan resistor, so that is unlikely to be the culprit. Even if it is, why wouldn’t it shut off? Other people with a bad blower fan resistor say that the speed control is stuck on high, but the fan can be turned on and off.
Could it be the electronic climate control module inside the cabin? AFter all, it is the unit that tells the blower fan to go on. Air could be directed to defrost, vent and floor without any problem.
What do you think is making the fan stay on at HIGH and does not turn off?
I would have to see a wiring diagram to know for certain, but I have owned cars that had a relay for the high fan speed. The resistor pack gave the lower speeds, but when the fan was set to high, the resistor was bypassed and the power went directly to the blower motor. If this is the case, trace the feed wire from the blower fan back and see if there is a relay.
I agree with Triedaq…But it could be the fan speed control switch too…The fan speed is not controlled electronically. It’s controlled by a rotary switch on the heater panel…
@Caddyman, he had electronic climate controls. The climate contol module does control the fan speed electronically through thr resistor pack. There is no rotary fan speed switch. Just buttons.
Looked at the prints and Treedaq is correct. The blower motor relay provides the High speed and the resistor pack provides the speed control. More than likely the relay is stuck and needs to be replaced.
A lot of vehicles using climate control use a solid state module to control the motor speed which is usually tied directly to power at all times. The modules can fault by either opening up, which will disable the blower, or short, which will run the blower at full speed since power is directly supplied to the blower. You either have to remove the fuse to the module or disconnect the battery to turn the blower off. Replacing the module should cost you a little over 100 dollars. Following the wires back from the motor will lead you to the module which should be screwed to the air ducting for cooling.
I read your email Roger124. Even though you can shut the fan off using the ignition switch I think it just means the module power is run through the ignition system and not directly to power as some others I have seen. Either way, I think module output is shorted to the power input so it applies power to the motor regardless of the fan speed control position.
There is a blower speed control module if the car has Automatic Temp control. If it has blower speed control resistors the switch could be bad or the relay is stuck on.
“It was an electrical problem - the con rod went through the block and knocked the distributor off.”
Reminds me of a funny story. Years ago had a customer with an aging Chrysler Minivan. She was out of town when the car quit on the road and wouldn’t start, not even turn over. Her teenage son looked under the car and said “Ma, the starter fell out.” So this lady has the car towed 200 miles back to me, since we had replaced the starter 6 months previous. She hands me the $600 tow bill and demands to be reimbursed on top of replacing the starter under warranty. What had actually happened was that she ran the engine out of oil and the rod broke the starter off when exiting the engine block.
Maybe the root cause is an aged blower motor that is pulling a lot of amps. Those excessive amps in turn could be causing the blower module to fail due to heat.
Even a blower that sounds like it’s fine can actually be defective and drawing a godawful amount of current.
@asemaster, I’ve seen those kind of incidents involving misplaced blame too.
Thanks again to @knfenimore for the service data. It appears the system can use either of the two speed controlled methods. I am still assuming that the speed control is variable so that would indicate the solid state speed control module is being use in this case. I see it is on the return side of the motor circuit instead of the hot side. The relay located on the hot side is always ON with the ignition so that is how power is getting cut off to the motor when the ignition switch is turned off.
If I understand it right, the speed control module has already been replaced in the past so this would really emphasize getting the motor current checked before installing another unit, like @ok4450 and I mentioned earlier. In case the motor is drawing too much current and that is causing the damage to the module.
Hey I can’t figure how to post a question so I will tag along on this one seeing that I have the same car.
Problem- Check Engine light is on
Code reads running lean with 2 bad O2 sensors
Is it the O2 sensors or is a vacuum line causing it to run lean and trip the code?
Great story @asemaster. Pro mechanics I think must have a lot of funny stories about the way their customers behave sometimes. People have a complex relationship with their automobiles, almost like a marriage between the driver and the car, and the mechanic is sort of like a therapist, someone who sorts the driver/car relationship problems out. And the mechanic, like the therapist, can sometimes find themselves in the middle of an argument they have nothing to do with.
When you work with the public, anybody who can walk in off the street, I guess you got to expect some weird behavior. I visited a gym one time, and while I was checking in, this guy comes to the front desk and shows his membership card. The staff say “sorry, but this card isn’t for this gym”. The guy shouts and screams and lays into the poor teenager staff member with numerous invictives and explitives, just a kid there at the front desk.
Finally, I say to the guy “what does it say on your card”. He says “xyz gym, full member”. I say “xyz gym in on the next block”. He storms out the door continuing his yelling “I am to be treated with respect!!!” … lol
@zacklong … you’ll have better luck getting answers to your question if you post in a separate thread. The experts here can give you some good tips on that question, as it is a common problem. See that big red box at the upper right of this page labeled “Ask a Question”?
