A/C - Blower Motor Operates At Engine Start Up

Article No.
93-15-9

07/21/93

AIR CONDITIONING - BLOWER MOTOR OPERATES AT ENGINE START UP WHEN ENGINE IS COLD

LINCOLN-MERCURY:
1993 MARK VIII

ISSUE:
A/C blower operating at engine start up, when the engine is cold and the EATC system is in the AUTOMATIC MODE, may be caused by a faulty or intermittent ground circuit at the heater core lockout sensor (also known as the CELO or cold engine lockout switch). The sensor is located in the heater core inlet tube.

ACTION:
Replace the nut which attaches the heater tube support bracket to the back of the engine with a serrated nut. The support tube bracket may not be making a good ground connection through the paint coating on the bracket. Refer to the following procedure for service details.

SERVICE PROCEDURE





1. Locate the heater inlet tube and heater core lockout sensor which is attached to the tube. Refer to Figure 1.

2. Replace the the heater tube attaching nut with a serrated nut. Refer to Figure 1.

3. Tighten the nut to 9 to 11 lbs.ft (12-15 N-m).

4. Verify that a good ground has been made by checking continuity between the sensor base and engine block, or by checking continuity between the heater core inlet tube (which is the lower of the two tubes) and the engine block.

a. Scratch the paint on the tube and the engine block, to assure good contact.

b. Test continuity with test lamp.

PART NUMBER PART NAME CLASS

N800907-S2 Nut - Serrated S

WARRANTY STATUS:
Eligible Under Bumper To Bumper Warranty Coverage

OPERATION DESCRIPTION TIME
931509A Replace Nut On Heater 0.7 Hr.
Tube Bracket, Includes Time
To Check Continuity
Between Heater Tube And
Engine Block.

DEALER CODING
BASIC PART NO. CONDITION CODE
12A648 93

OASIS CODES: 203200, 208300