Blower Motor fan not working properly

KATHERINE BREWER

MEMBER
1997 LINCOLN TOWN CAR
125,000 MILES

Initially, EATC would cycle off if I turned on any heat until the engine was hot. This would take 12-15 miles drive time. At that point EATC came on with hot air. The rest of the system was okay.

About 4 years later, with 6,000 mi/year, there was a slight odor coming from vents with only unchanged air - no heat or A/C setting. Vaguely like hot plastic. My solution: turn it off.

6 months later, unpredictably, fan would come on. I'd turn it off using the off button. A few months later the fan would come on more often. The odor would return after some minutes. This happened in fall. And the fan stopped coming on when it got cold outside (below 32).

I had a new blower motor resistor installed by a local competent mechanic. Things shifted. 1) Heat comes on now without waiting 15 minutes (roughly 15 miles). 2) EATC does not shut off when you dial in heat when vehicle is cold. 3) But you can't turn the fan off without turning off engine completely and 4) if you press EATC off, the fan sends all air to floor and seemingly at a higher rate
than before.

Mechanic thinks part Made in China is defective.

1 Reply

WENDY W

MECHANIC
86 POSTS

Hello!

It is possible that the speed control module that was replaced was a defective part. There also could be a fault within the Electronic Automatic Temperature Control (EATC) module or between the connector and the module that may be causing the erratic operation.

If any fault codes have been stored, you may be able to display them by pressing the “off” and “floor” buttons on the EATC module at the same time, then releasing them and within 2 seconds pressing the “recirculate” button. Please take note of any codes stored. If you press “front defrost” this should clear the codes but not necessarily remove the fault.

You could also check the connector at the back of the EATC module for any corrosion or bent pins.

If you check resistance on the circuit between the data link connector, tan wire with orange stripe, and the EATC module connector, pink wire with light blue stripe, there should be less than 5 ohms of resistance.

Next, you can check resistance between the data link connector, pink wire with light blue stripe, and the EATC module connector, tan wire with orange stripe. There should be less than 5 ohms of resistance in this circuit as well.

This repair guide explains how to measure resistance in a circuit:
https://www.2carpros.com/articles/how-to-use-a-voltmeter

This guide explains a few things that can go wrong in a vehicle's climate control system and how to possibly perform a climate control reset:
https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

Please check out the diagrams I've attached (below) for the air conditioning system. It's in two parts to help make it easier to read. I've also attached a schematic for the computer data lines and diagram that may help if the EATC module needs to be removed.

Please let us know what you find.

Thanks, Wendy W

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