evaporator discharge air temperature sensor -- 2002 TBird

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...
 
Does the manual have the procedure for the evaporator replacement? The sensor would be in the same area. Typically to get at and change an evaporator, you need to drop the steering column and unbolt and raise the dash panel. A $1500 price from a dealer would be typical for that work. I did an evap. change on a Caravan, it was eight hours. Try to pull the glove box and see if there would be any access or possibly through the radio hole. I've been known to get the sensor first so I know what I'm looking for. If you could find the similar plug on the harness in the area you could plug in the new one and see if it works before a major dismantle. A wiring diagram may help. I have the '03 manuals, but not available at this time. The're in the car trunk at storage for winter. If you need I will get them, I should go check on 'Her' anyway!! :D
 
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Thanks - the part is coming from Rockauto ($24) and I'll get a close look then - maybe there's a shortcut...

I did look a the heater core R&R procedure in the manuals (which I have) and unless a miracle occurs you are correct, its a dash (entire frame) pull and not just the instrument gauge cluster. It involves removing the driver air bag, completely disconnecting the gear shift lever, including underneath the car, unplugging a bunch of fragile electrical connectors. And that's just for starters...

I will have had this car one year on Valentine's Day and have had to repair the instrument cluster, dash lights and FEM already (non-trivial repairs). I'll stew on it a while but I may just pay the dealer and sell the car down the road.... These major expenses are ridiculous on a one-owner, 25,000 mile car... Very frustrating.

There are some "shortcuts" on Youtube for other cars owners have done; like "hardwiring" a resistor in an easily accessible place to act as "fixed" temp sensor. I'll have to study those some more...
 

biddle

Forum Moderator
Staff member
Thanks - the part is coming from Rockauto ($24) and I'll get a close look then - maybe there's a shortcut...

I did look a the heater core R&R procedure in the manuals (which I have) and unless a miracle occurs you are correct, its a dash (entire frame) pull and not just the instrument gauge cluster. It involves removing the driver air bag, completely disconnecting the gear shift lever, including underneath the car, unplugging a bunch of fragile electrical connectors. And that's just for starters...

I will have had this car one year on Valentine's Day and have had to repair the instrument cluster, dash lights and FEM already (non-trivial repairs). I'll stew on it a while but I may just pay the dealer and sell the car down the road.... These major expenses are ridiculous on a one-owner, 25,000 mile car... Very frustrating.

There are some "shortcuts" on Youtube for other cars owners have done; like "hardwiring" a resistor in an easily accessible place to act as "fixed" temp sensor. I'll have to study those some more...
What is the part number or link to part for future reference?
 
These major expenses are ridiculous on a one-owner, 25,000 mile car... Very frustrating.
I agree... I Like Ford's, and the T Bird has the styling, nostalgia, and fun to drive, but it is not one of their finest achievements with all the new-unproven technology and failures. These cars are often less used and better cared for than most vehicles, yet failure rates on many components seems higher. My '15 F250 has 100k+ miles with lots of towing and most I've done is replace one cracked exhaust manifold and regular maint./ brakes/ ect. Several Dodge Caravans with 250k+ (the wife drives one of these everyday) one had 380k+ miles until I wreaked it. And I never had to replace a computer or the suspension because of poor quality joint boots.
 
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TBIRRRD

Active Member
I had the part replaced on my 2004 tbird last year. The work was performed by a Ford garage. They have performed all my work since the car was new. The same part number was 54.99. Labor was $197. After the mechanic saw the part was a push and twist or plug in of some type with no wires and screws he changed it out without removing the dash or steering column. He may have removed something small , not sure. He said the manual called for removing the dash , but said after seeing the part found another easy way. I bought him lunch. Part XW4Z-19C734-BA . Good luck
 
I'm hoping I can reach behind the instrument cluster when removed and get to it, but I'm doubtful I'll be that lucky.
Maybe you could inquire with your mechanic as to the exact "trick" he found and let us know; others here might benefit as well...
 
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I had the part replaced on my 2004 tbird last year. The work was performed by a Ford garage. They have performed all my work since the car was new. The same part number was 54.99. Labor was $197. After the mechanic saw the part was a push and twist or plug in of some type with no wires and screws he changed it out without removing the dash or steering column. He may have removed something small , not sure. He said the manual called for removing the dash , but said after seeing the part found another easy way. I bought him lunch. Part XW4Z-19C734-BA . Good luck
The purpose of this part is mainly to keep the evaporator from freezing up when the A/C is running full blast on humid days...typical symptoms when this part fails "open" are the A/C compressor won't cut on - soooo - no A/C. My symptoms are different with A/C or heat working well but not regulated by the dash setting.. So, I'm hoping the dealer diagnosis is correct.

I'm wondering if your mechanic's $197 "fix" was one of the options I've seen on Youtube (particularly with Ford Fusions) where you can tap into the harness connector (often behind the glove box) and either put a resistor across two of the terminal wires or else put the actual new sensor in the same spot but just "sit" it behind the glove box and not try to install it in the evaporator ? This could cause the evaporator to freeze up on rare occasions but avoid the huge labor bill to put the sensor down into the evaporator.
 

TBIRRRD

Active Member
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.
 
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.
IMG_1946.jpg

TBird Rear Dash.PNG
 
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biddle

Forum Moderator
Staff member
Here are some pics I found online showing alternate access:


Set up this pillow arrangement to save my back.
1.jpg


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


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


Tested it again...WooHoo!
4.jpg


This is the package with the two sensors...
5.jpg


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


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?
7.jpg
 
Thanks Biddle - that's the thread I found....
The procedure described there is not 1/2 as tricky as pulling the entire dash for sure.....
The part is inbound and I'll provide and install update when I get the job done..
 
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