2004 Taurus: i want to bypass the a/c unit...

That's not the way you do it, you remove the AC Compressor and fit a Bypass Pulley in its place. The belt and routing remain the same.

https://www.google.com/search?q=2008+ford+taurus+ac+bypass+pulley

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That's not the way you do it. You fit a Bypass Pulley. It keeps the same belt, route and tension.

Ford Taurus A/C Compressor Bypass Pulley ' AutoZone.com

https://www.autozone.com > ... > Air Conditioning
Buy Ford Taurus A/C Compressor Bypass Pulley online and get Free Next Day Delivery on qualified purchases, or pick up your parts at a nearby AutoZone today.
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No, because the routing doesn't work out right.

https://www.2carpros.com/diagrams/ford/taurus/2002

So they sell Bypass pulleys and you just use the same belt.

https://www.google.com/search?q=2002+ford+taurus+3.0+l+AC+compressor+bypass

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Dorman sells bypass pulley bracket units to route the existing belt by replacing AC unit . Some cars have a optional belt for non AC cars .

2004 ford taurus belt size to bypass ac compresser is 68inche belt i spent 7 hours testing 5 differnt belts 82 inchs is standard belt not a bypass belt 680k is the belt not a perfect fit you need to buy a smaller idler pulley smooth no groves then you have perfct fit i just wnt through this today all day

2004 And 2005 There is no bypass pulley manufactured, even though all of them come with AC. but I am learning although mechanics dont want to admit it, if you remove the ac pump a shorter belt WILL work, in fact it will work (very temperorerly because there is a slight rub) without the removeal of ac pump. but a 15 milmeter wrench will get it home to remove the AC pump about 4 hours labor. Orielly's master pro K060815, Auto Zone 822K6, or preptstone 825K6 will work.
GOOD LUCK FRIENDS

The heater unit has a drain and if its blocked the condensate from the AC will run out all over the carpet ,Sorry not familar with this model have a good look and iam sure you will find it .

Hi
I'm not sure on the correct belt length but you can bypass the A/C pump and it wont affect the vehicle
Hope this helps Nick

yes on both accounts. you can by pass the compressor by getting a serpentine belt for a non air conditioned car.Why do you feel that the a/c compressor is the problem? 

You can try to replace with a similar unit, but typically Ford ECUs have to be "reflashed" by the dealer. Ford has numerous calibration codes and various other vehicle specific information that can only be managed with Ford certified (dealer) programing devices. I hope this helps