evaporator discharge air temperature sensor -- 2002 TBird

[Frankie the Fink]

OK - my 25,000 mile, one owner 2002 TBird now has the climate control acting weird, in AUTO or MANUAL, DUAL or SINGLE, the heat will only blow with the temp over 82* and below that its A/C. You will freeze if its 62* out and you set the cockpit temp at 74*. I already changed the "ambient air sensor" behind the small grill in the dash near the ignition switch - didn't help...

The dealer says its the evaporator discharge air temp sensor (a $25 part) but it'll cost $1,500 labor to replace it and requires the instrument cluster to come out, yada-yada. Ridiculous. The Workshop and Service Manuals identify the part (which I've ordered) but no procedure to replace it...the part is apparently up inside the right hand side of the driver area in the evaporator somewhere.

Any insights or experience are appreciated...I searched the forum and found almost nothing on this issue...

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[TBIRRRD]

I do not know about the utube fixes. The diagnostic code was DTC B1947 was the reason for replacing the part. The problem was the auto temp would not hold set point on air or heat. Also on the analysis sheet (included with the charges) was the fact that the evaporator discharge temperature sensor is biased. At an ambient temperature of 82 , specified value should be 25, 000 ohms and it measured 10,300 ohms. Part replaced and all has been well for 6 months.

 

[Frankie the Fink]

That's a bit of comfort since your symptoms mimic my own and so I think the part is indeed bad as the dealer has diagnosed...

I honestly don't see how your mechanic replaced it for less than $200. At this rate, it would pay me to fly him to Florida have him change the part and fly him home and I'd still be hundreds ahead. I would sure like to know his "trick"...

I now have the gauge cluster out and peering behind it there is certainly no way to access that part through that avenue.

 

[biddle]

Here are some pics I found online showing alternate access:


Set up this pillow arrangement to save my back.



I worked blind under the dash and reinserted the sensor into the connector. Then I tested it. WooHoo!



I placed it back into the hole in the A/C plenum; it went in very easy without looking at it.



Tested it again...WooHoo!



This is the package with the two sensors...



This is what it looks like in the plenum (white rectangle)...



This is what it looked like with the 33K ohm resistor in connector C296 for testing.
See the little hole to the right it fits in?

 

[Frankie the Fink]

Following the directions above, and by spending $25 for the sensor, my issue was fixed in 10 minutes...
So much for the dealer's $1,500 labor charge estimate, they didn't do their homework as the sensor is as shown above easily accessible on the left hand side of the heater box and NOT all the way at the rear where you can't reach it.

 

[Cleavermodels]

Frankie the Fink, I have a 2002 T-Bird with 24,260 miles since I bought it new. I have been experiencing the same problems with my DATC. On Auto mode the car does not give out heat until you move the temp up to 80. Under that you get the A/C blowing. I was going to try replacing the Ambient temperature sensor behind the front grill and try to replace the Climate temperature sensor behind the dash grill to see if that would correct the problem. The Climate Temperature sensor XW4H-19C734-AB. I can only find is used and the only one that MAY BE new is from Thunderbird specialties for $99 and I am not about to deal with the proprietor anymore without going into detail. The fix described by you and Biddle seems what I actually need. You mentioned a thread you found. Can you let me know what the thread is and how I can find it? I do not want my impeccable interior pulled apart for a fix that seems very simple. Thanks! Cleavermodels. If you prefer you can call me at <PLEASE DON'T POST PHONE NUMBERS PUBLICALLY>

 

[biddle]

I can only find is used and the only one that MAY BE new is from Thunderbird specialties for $99 and I am not about to deal with the proprietor anymore without going into detail.

Then buy the one on Ebay-

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Use the search feature on the site, read the posts above and also see this A/C thread- https://forums.fordthunderbirdforum...ne-side-2002-2003-2004-2005-thunderbird.9446/

 

[Frankie the Fink]

That ebay sensor above is located in the dash and honestly, it is such a simple piece there is almost nothing to go wrong with it. If you DO pull it out, you'll find its basically a thermistor housed in the airflow stream of the part. I suspect is more of a "fine-tuning" device to detect cabin air temps and make fine-grained adjustents.

I would be much more suspicious of the evaporator discharge air temp sensor discussed at length above. It just twists in from under the driver's dash - I would say that is a more likely candidate for causing your problem.

 

[Cleavermodels]

Frankie,
Thank you for your reply. I just purchased on e-Bay the used climate temperature sensor referenced by Biddle above (since no new ones can be found), also a new ambient air temperature sensor, and will get a new evaporator discharge air temp sensor and follow your advice for installation. I went to my dealer today and was told flat out that if Ford says to drop the steering column and lift out the dash then that is what they will do for installation of the evaporator air temp sensor. I thanked them and drove off. I am purchasing all three for the future but will install the evaporator discharge air temp sensor following your instructions! Cleavermodels

 

[Frankie the Fink]

That is exactky what you should do, the evap air temp sensor is a 5 minute job, that cabin air sensor in the dash is an all-dayer and involves some delicate work. I've done the dash pull more than once, if you booger something up, a simple parts swap becomes a major PITA.