Fan control will not work. Knob turns but fan wont come on.

[bwc]

Does anyone know what the problem/solution could be?
I have a ’97 civic sedan. When I turn the fan knob on nothing happens. The fan isnt coming on, no heat or AC will come out. I checked the fuses and none are blown. I pulled the knob off and the actual metal piece turns fine... this just happend the other day for no apparent reason.
any ideas??

thanks

 

[W????n S.]

Does anyone know what the problem/solution could be?
I have a '97 civic sedan. When I turn the fan knob on nothing happens. The fan isnt coming on, no heat or AC will come out. I checked the fuses and none are blown. I pulled the knob off and the actual metal piece turns fine... this just happend the other day for no apparent reason.
any ideas??

thanks

On my honda it was the motor itself. Interesting to fix but not hard per se. 88 honda accord lxi.

 

[James Sweet]

Does anyone know what the problem/solution could be?
I have a ’97 civic sedan. When I turn the fan knob on nothing happens. The fan isnt coming on, no heat or AC will come out. I checked the fuses and none are blown. I pulled the knob off and the actual metal piece turns fine... this just happend the other day for no apparent reason.
any ideas??

thanks

I assume this applies to all speeds? Many cars use a resistor to drop the motor voltage for the lower speed settings, then bypass it for the high speed. If the resistor burns out you get high speed or nothing. If that doesn't work either, the next step is to check for voltage at the power terminal on the motor, some cars this is easy, others it's as if they put the blower motor on a pedestal and built the car around it. Also you mention you checked the fuses, but you may want to try replacing the blower fuse anyway, or at least make sure that other accessories, if any, on the same circuit work. It's rare, but I've seen mechanical failures in fuses where the element cracked off at one end, still appearing intact but not completing the circuit.

 

[bwc]

Thanks for the help guys!

Well mechanic says its the Heater Blower Control Motor, and its close to 400 for the unit (or whatever it is).

Anyone know anything about that, and if I could easily do it myself or if I could find it cheaper? Why would it just die for no apparent reason??

Thanks agai

 

[bwc]

oops the car is a 2003 not 97 (if it matters)
and the part as per mechanic is called "heater control head assembly

 

[James Sweet]

Thanks for the help guys!

Well mechanic says its the Heater Blower Control Motor, and its close to 400 for the unit (or whatever it is).

Anyone know anything about that, and if I could easily do it myself or if I could find it cheaper? Why would it just die for no apparent reason??

Thanks again

Sounds like it uses an electronic controller for the fan motor instead of a simple resistor and switch. If you can open it up, there's probably a power FET driving the motor, these tend to fail shorted though so I would first look for hairline cracks in the solder joints under the circuit board around this and the pins on the connector where the wiring harness plugs in. Assuming you lack the skills to diagnose and repair this, you could try and find someone who does, or keep an eye on ebay or call some salvage yards. Could look online for parts suppliers but this sort of thing is often a dealer-only part.

As for why it would die, this sort of thing happens all the time. One major challenge in mass producing printed circuit boards is soldering when you have a mixture of components with large heavy leads and small light stuff. It's tricky to wave solder it such that you get sufficient solder on the heavy stuff without burning up the small parts. On top of this you have vibration and mechanical shock which can lead to fractures, and temperature swings causing fatigue from expansion and contraction, a car being a particularly harsh environment in both respects. Components can fail as well, but I have seen surprisingly little of this in automotive electronics. Shorted capacitor in the ECU was the fault preventing a friend's VW Scirocco from starting, seen a few bad ones that would cause dashboard clocks and speedometers to function erratically or not at all in cold weather, but overall not very many. Sometimes the design and construction are quite adequate and things just fail, luck of the draw, it happens.

If the thing is already dead, there's no harm in popping it open to have a look, so long as you know you're popping open the correct part.

 

[Michael Pardee]

Car-part.com lists a bunch in my state, including a couple at my local wrecking yard, ranging from $50 to $110. Give it a try!

Mike