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1998 Lincoln Town car Getting code 31 in Auto Temp Control what is the meaning of that code. no temp control either hot or cold

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  • Lincoln Master
  • 15,575 Answers


    NOTE: An open sensor will cause warm air discharge at 18°F (65° C) setting. A shorted sensor will cause cool discharge air at 29°F (85°C) setting.
  • Disconnect the A/C ambient air temperature sensor.
  • Using an ohmmeter, measure the resistance across the sensor terminals and compare the readings with the following sensor resistance table:

    Approximate Temperature Sensor Resistance Acceptance Range 10-20°C (50-68°F) 37K-58K ohms 20-30°C (68-86°F) 24K- 37K ohms 30-40°C (86-104°F) 16K-24K ohms
Are resistance values within the specified limits?
Yes No GO to B2 . REPLACE A/C ambient air temperature sensor and bracket. RESTORE vehicle. RETEST system. B2 CHECK ASPIRATOR INSTALLATION
  • Gain access to automatic temperature control sensor.
  • Check for proper installation of automatic temperature control sensor hose and elbow.
Is aspirator installed properly and hose connected?
Yes No GO to B3 . SERVICE automatic temperature control sensor hose and elbow as necessary. RESTORE vehicle. RETEST system. B3 CHECK CIRCUIT 470 (PK/BK) AT AUTOMATIC TEMPERATURE CONTROL SENSOR
  • Turn ignition switch to the RUN position.
  • Turn EATC module to NORM A/C position.
  • Disconnect automatic temperature control sensor.
  • Using a voltmeter, check Circuit 470 (PK/BK) for voltage at sensor connector.
Is voltage 5 volts?
Yes No GO to B5 . GO to B4 . B4 CHECK CIRCUIT 470 (PK/BK) FOR OPEN
  • Disconnect connector C227 at EATC module.
  • Using an ohmmeter, check Circuit 470 (PK/BK) between EATC module and automatic temperature control sensor for open.
Is there 5 ohms or less?
Yes No SERVICE Circuit 470 (PK/BK) for open. RETEST system. GO to B5 . B5 TEST CIRCUIT 470 (PK/BK) FOR SHORT
  • Using an ohmmeter connected to a good ground, connect other lead to EATC module connector Pin C227 , Circuit 470 (PK/BK).
Is resistance less than 10,000 ohms?
Yes No SERVICE Circuit 470 (PK/BK) for short. RESTORE vehicle. RETEST system. GO to B6 . B6 TEST CIRCUIT 790 (W/O) FOR OPEN
  • Using an ohmmeter, connect one lead to EATC module connector Pin C227 , Circuit 790 (W/O) and other lead to automatic temperature control sensor Circuit 790 (W/O).
Is resistance 5 ohms or less?
Yes No GO to B7 . SERVICE Circuit 790 (W/O). B7 TEST CIRCUIT 790 (W/O) FOR SHORT
  • Using an ohmmeter connected to a good ground, connect other lead to EATC module connector Pin C227 , Circuit 790 (W/O).
Is resistance less than 10,000 ohms?
Yes No SERVICE Circuit 790 (W/O) for short. RESTORE vehicle. RETEST system. REPLACE EATC module. RESTORE vehicle. RETEST system.

Posted on Mar 24, 2018


6 Suggested Answers

  • 2 Answers


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Posted on Jan 02, 2017

  • 49 Answers

SOURCE: Heater only blows hot (well, warm) on full speed of fan

Replace the temp control on this car, it should be electrical control not cables.

Posted on Dec 03, 2008

michigan man
  • 3533 Answers

SOURCE: 1998 Pontiac Bonneville heater problem

take the upper radiator hose use a glove and while the car is running squeeze the hose together and see if trys to open in your hand and if it doesn't you have a weak water pump but check the condition of the drive belt and the coolant before you go to the pump

Posted on Jan 05, 2009

  • 15935 Answers

SOURCE: heatercore does not get hot only one hose is hot

The heater in your car depends upon a flow of hot coolant going through the heater core in order to get hot air into the car. If the heater core is partially plugged, it will restrict the flow. If you have a head gasket that is putting exhaust into the cooling system, it will eventually get into the heater core. When this happens there is no coolant in the heater core to make the air warm. If the water pump vanes have corroded away the result will be very poor coolant circulation causing the heater to not blow hot air. If your car is equipped with a heater control valve that is not functioning properly, the coolant flow will be restricted. One or a combination of these factors is likely the culprit in your case.
Flush the heater core 2-3 times, and if the obstruction does not clear, a new heater core is required.

Posted on Jan 29, 2009

  • 22484 Answers

SOURCE: passenger side blows hot air when front control set to Air

you cant adjust it ,this requires the dealers computer to re set it,or a phyiscal control has packed up like a vacumn pipe has split where it pushes onto the valve that controls the flap in the heater unit.

Posted on Apr 26, 2009

  • 105 Answers

SOURCE: 2002 Pontiac Montana, No Heat, I put the temp control on

the cabel from the heat dial to the heater box behind the dash could be snaped or jamed thus not opperating the lever which operates the flap which open and closes the heat box next to the matrix. or if your coolant is brown in colour it could be your matrix is clogged with sedament and needs flushing out. or it could be your water pump not pumping coolant round your engine or it could be a knackerd thermostat i hope these will help you id start with the easyest first thermostat

Posted on Dec 17, 2009

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