1999 Mercury Cougar Air blending or distribution

Tiny
RED-OAK
  • MEMBER
  • 1999 MERCURY COUGAR
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 150,000 MILES
When in A/C mode the 2 vents for the driver blow warm while the 2 vents for the passenger blow cold. A/C is functioning. The blend door motor works, and I can move the door itself by hand with the motor removed. I can't find anything else without taking the entire dash apart, not something I want to do unless it is worthwhile. All the heat and air controls work normally except occasionally the fan speed control has to be twisted back and forth to get the fan on, this is not related to the other problem though. This is my first time trying one of these forums and I want to see how it works before we talk donation, but I like the idea of it going to the tech that deserves it. But how do I know where it goes?
Tuesday, April 13th, 2010 AT 3:46 PM

5 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
If it has auto temp control try this self test, post all codes displayed!
Run the self diagnostic test on it by turning the key to on, then press off and floor at the same time, then within 2 secs, press auto, If there is a problem a trouble code will appear on the display. To exit self test, press the BLUE, cooler button this also retains error codes, To erase codes and exit, press defrost, choose one of these before you power down the system. Test with engine at 120 degrees or more, and cabin between 40-90 degrees. Post any codes recorded here and I let you know what's defective.
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Tuesday, April 13th, 2010 AT 4:17 PM
Tiny
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  • 3 POSTS
It does not have any auto temp control or zone controls
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Tuesday, April 13th, 2010 AT 4:26 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Then I can tell you if you can move a blend door by hand, it's broken, others in the plenum may be damaged too, but check the charge on the R134, low charge, or weak compressors will do this too. Put a manifold gauge set on the system and take readings.
A normal system will show 200 on the high side and 35-45 on the low side.
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Tuesday, April 13th, 2010 AT 4:43 PM
Tiny
RED-OAK
  • MEMBER
  • 3 POSTS
It does have to be re-charged every year or so, but it is blowing cold from the 2 vents on the rt side of car. The blend door may be broken, but if that little motor can turn the shaft and move the door I should be able to do it by hand easily. Also I can hear it when it goes down against the landing. That's why I think there must be something else in the ducting or distribution that is adding warm air on the ducts leading to strangely to me just the 2 vents for the driver. By the way, thanks for your input.
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Tuesday, April 13th, 2010 AT 4:59 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
You would be amazed at what drops into the ducting!
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Tuesday, April 13th, 2010 AT 5:04 PM

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