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Ask Ronnie Your Own Question
Ronnie, ASE Certified Technician
Category: Lincoln
Satisfied Customers: 35623
Experience:  35 years as an automotive tech
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2002 LS with the 3.9. No heat, A/C is sporatic, no defrost

Customer Question

Good morning. 2002 LS with the 3.9. No heat, A/C is sporatic, no defrost (also A/C does not come on with defrost). I ran the HVAC self test and got the 1966 code. Help?
Submitted: 1 year ago.
Category: Lincoln
Expert:  Ronnie replied 1 year ago.

Hello and thank you for your question,

The code 1966 indicates you have a problem with the Driver heater core discharge temperature sensor open circuit. Are you able to do some testing if I provide you with the procedure?

Expert:  Ronnie replied 1 year ago.

I have enclosed the test steps in the link below for testing the code 1966. Copy and paste the link to your browser to open and view them.

Customer: replied 1 year ago.
Ronnie, I appreciate the shop manual, but I don't own any of those diagnostic tools. I'm just a guy in his garage trying to keep this LS running with 217,000 miles on it. Fyi, I now have both codes 1966 and 1947. Can I not just replace the sensors, or whatever else is acting up? If so, how do I do that? Thanks.
Expert:  Ronnie replied 1 year ago.

You can try replacing the sensor if you are not able to do the testing but you do run the chance it may not be the problem. Both codes indicate you have a problem with the discharge temperature sensor so its worth a shot and may very will resolve the problem.

Customer: replied 1 year ago.
I think I will try that. My main problem with the car though is the windshield fogging up to the point of not being able to drive the car. There is no air going to the defroster (but it sure sounds like it's blowing) and the air conditioner does not kick in with the defroster. My guess is that the sensor is not the problem with that (?). Would you guess that that is a bad flap motor under the dash?
Expert:  Ronnie replied 1 year ago.

The AC needs to kick on in order for the system to remove the moisture from the incoming air, if you can get the AC compressor to run then that should solve the fogging problem. If you are not getting any air flow in the defrost mode then yes you may have a actuator issue.

Customer: replied 1 year ago.
Ronnie, wouldn't the HVAC diagnostic test discover a bad defroster actuator? I can hear them opening and closing during the test. If the test does not uncover a bad defroster actuator, how can I test that? If the blower is blowing in defrost mode but I am getting no air to the windshield, I can't imagine what else could be wrong other than the defroster actuator (?). Comments?
Expert:  Ronnie replied 1 year ago.

The defroster actuator controls the defrost door. The code 1947 indicates a problem with it and or the signal and or circuit to it.

Customer: replied 1 year ago.
Thank you. So what is the next recommended step to getting the defroster fixed?
Expert:  Ronnie replied 1 year ago.

Unfortunately the next recommended step would be to do the proper testing to avoid replacing parts that may not be needed.