Town Car BMSC Blower Motor Speed Control replacement

[Town]

The Blower Motor Speed Control (BMSC) is an electronic module that controls the grounding circuit for the HVAC blower motor through the EATC on automatic or manual control. The symptoms of a failure are the blower fan running when the EATC is switched to OFF or the blower fan only running at one speed. If the blower fan does not run at all then make sure it is getting power and missing the ground circuit before replacing the BMSC.

The attached procedures detail the BMSC replacement for a 2007 model but should also apply to the 2003 and up models. I have attached the wiring diagram for the BMSC to aid in trouble shooting an electrical problem.

Good luck.

 

[Town]

BMSC replacement for 2000 model Town Car

The BMSC is located at the Right Rear of engine compartment, on the A/C evaporator. It controls the grounding circuit and therefore the speed of the HVAC blower fan according to the EATC automatic or manual speed control. The BMSC on the 2000 model Town Car is readily accessible without removing the heater hoses and therefore draining the cooling system.

Attached is the replacement procedure for the 2000 model, the 1998 thru 2002 models are believed to be similar.

Good luck.

 

[driller]

Thanks Town.

I've been meaning to tackle this on out '06 Town Car. I knew where the BMSC was but didn't know the heater hoses needed disconnected.

 

[Town]

Attached is the wiring diagram for the 2001 Town Car EATC which shows in 55-3 the wiring for the BMSC. If the BMSC is suspected as failed then test the orange/brown wire powering the blower fan for 12 volts and the orange/red ground wire from the BMSC at 0 volts (ground) when blower control at EATC is at full speed. Check the black wire from the BMSC to ground that it is 0 Volts. If all 3 tests show normal readings then replace the BMSC.

Good luck.

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[Town]

The BMSC wiring diagram is attached to help determine the wire colours for testing BMSC. Note the power supply to the blower fan comes through a fuse and relay.

 

[Town]

The location of the BMSC in the engine compartment of the 1998 thru 2002 Town Cars is shown in the attached document.

 

[Racky]

I would like to check the relay but cannot find it. The labels in the engine bay on the relays do not say which one is for the blower motor and the manual that comes with the car does not tell you either.

 

[Town]

I would like to check the relay but cannot find it. The labels in the engine bay on the relays do not say which one is for the blower motor and the manual that comes with the car does not tell you either.

There are no relays for the blower fan. In post #4 above you will see the wiring diagram you need in diagram 55-3. Note that the blower motor is powered from the central junction box in the passenger compartment when ignition switch is in run position. The EATC controls operation of the blower fan by using variable resistance in the BMSC.

Hope that helps.

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[Legion76]

My blower runs continuous, when I remove the key from the ignition. Help, please!!!