Fan motor problem


#1

My dad’s 1993 Lincoln Town Car runs great but the fan for heat or AC only will run at full blast or nothing. Makes it difficult to drive when it’s real hot or cold out. Can this be remedied without costing an arm and a leg? The car is 21 yrs. old and not worth a lot.


#2

Could be as simple as a replacement resistor module. If it is manual control, a resistor module is about $20. It should have a 6-wire connector near the blower motor.


#3

According to the schematic, it has a solid state unit.


#4

You could try the self-diagnostic procedure with the EATC unit to see if any DTCs are present. The process is easy to do and is cut and pasted below. The blower speed has a number of influences.

The HVAC Module - EATC On-Demand Self Test will not detect concerns associated with data link messages like engine coolant temperature or vehicle speed signals. A scan tool must be used to retrieve these concerns.
The HVAC Module - EATC On-Demand Self Test will detect concerns in the system control functions and will display on-demand (hard fault) DTCs for concerns that are present during the self-test. The vehicle interior temperature should be between 4°C-38°C (40°F-100°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false DTCs may be displayed.
The self-test can be initiated after cycling the ignition switch from OFF to ON. Normal operation of the climate control system stops when the self-test is activated.
To enter the self-test, press the OFF and DEFROST buttons simultaneously and release, then press the AUTO button within 2 seconds . The display will show a flashing blower icon for 20 seconds , after which all vacuum fluorescent segments will be displayed if there are no on-demand DTCs present. If DTCs are present, the HVAC module - EATC will display "00 00" and then on-demand DTCs. Record all DTCs displayed.
If any DTCs appear during the self-test, carry out the diagnostic procedure. Refer to the HVAC Module DTC Chart and follow the ACTION for each DTC given. See: Diagnostic Trouble Code Tests and Associated Procedures\HVAC Module DTC Chart
If a condition exists, but no DTCs appear during the self-test, GO to Symptom Chart Condition: The EATC System Is Inoperative, Intermittent or Incorrect Operation. See: Symptom Related Diagnostic Procedures
To exit the self-test and retain all DTCs, press any button except DEFROST. The HVAC module - EATC will exit the self-test and retain all DTCs.
To exit the self-test and clear all DTCs, press the DEFROST button. The HVAC module - EATC will exit the self-test and all DTCs will be cleared.
Always exit the self-test before powering the system down (system turned OFF). Once the self-test is exited, the ignition switch must remain ON for at least 30 seconds to allow the door actuators to automatically recalibrate.
Continuous DTCs will be deleted after 80 ignition switch ON cycles after the intermittent fault occurs.

#5

On a 1993!!!

Yosemite


#6

The solid blower speed regulator is probably faulty

I say this, because on the Benz vehicles which I’m familiar with, the solid state blower regulator failed very often

Very easy to test, if you have a multimeter and the wiring diagram

And those also had all sorts of self tests, fault code readouts, etc., many of which could be initiated without a scan tool . . . if you knew the secret combination of buttons to push. If you didn’t, you needed to hook up the factory level scan tool

And this capability was available from at least the early 90s on

In fact, this diagnositic capability for auto ac was also common for Toyota, and probably many others, as well


#7

I have no A/C training. I could replace a worn/broken belt which the OP tried. I’m lost here.


#8

The self-test on Fords can be entered by just pushing the OFF and DEF buttons at the same time followed by quickly pushing the AUTO button.

It’s also possible this problem could be caused by the wire connector on the blower motor controller which has a tendency to burn sometimes. That is usually caused by an aged and dragging blower motor pulling a lot of current.


#9

I stand corrected!!!

Yosemite