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  1. #1
    Join Date
    Feb 2009
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    New York
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    53

    RTAA 1854 XRO1 A3D0 BFQ Sensors

    Hi All, My question is I have code 1d4, ordered replacment sensor sen0951, I seem to remember that they need to be changed in pair's ?? so is that the suction temp sensor on ckt 2 which is bad and which other one, also what direction dose the hole in the sensor face . thanks in advanced fred

  2. #2
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    4,443
    gotta change them in pairs...compressor and saturated evap temp sensors...no wire nuts...run the whole dang wire and loop it up under the unit nice and neat as the sensors are mated pairs WITH THE ENTIRE LENGTH OF WIRE INTACT.

    most will say that you can just change one or just wire nut it in and it will probably work ok...but these same short cuts are done by the same guys who i am currently following around and cleaning up their mess. who knows...maybe that is why you are having problems.
    How to make the perfect "Half-Hitch" knot or any other boyscout knot in 3 easy steps...

    1. Remove your meter leads from the meter and very carefully return them to their storage case or bag.
    2. Wait 2 seconds
    3. Very carefully remove your meter leads from their storage place and enjoy your new knot!

  3. #3
    Join Date
    Feb 2009
    Location
    New York
    Posts
    53
    Thanks JayGuy, your right about messes, there are old sensor wires stiill hanging around from prevous change out and wire nuts galor
    Last edited by FREDIEFREON; 04-30-2010 at 07:04 AM. Reason: update

  4. #4
    Join Date
    Sep 2006
    Posts
    85
    the holes face direction of flow

  5. #5
    Join Date
    Feb 2009
    Location
    New York
    Posts
    53

    RTAA

    Thanks Cooolguy,
    Will be changing out tomorow
    Fred

  6. #6
    Join Date
    Jan 2009
    Location
    Not in Iran
    Posts
    1,106
    Quote Originally Posted by jayguy View Post
    gotta change them in pairs...compressor and saturated evap temp sensors...no wire nuts...run the whole dang wire and loop it up under the unit nice and neat as the sensors are mated pairs WITH THE ENTIRE LENGTH OF WIRE INTACT.

    most will say that you can just change one or just wire nut it in and it will probably work ok...but these same short cuts are done by the same guys who i am currently following around and cleaning up their mess. who knows...maybe that is why you are having problems.
    what happens when u dont change in pairs? and why and what does compressor and saturated evap temp sensors have in common that they r looking at? differntal to start or??

  7. #7
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,081
    The sensors are a matched pair (resistance wise) . Jay your correct no joints no wire nuts no butt connectors and use the right tool to make off the connection at the UCM . As far as dont cut to length ??? Do you see an extra 30ft of cable coiled up in the wire harness on a factory untouched unit ???? No they cut them to lenght to make it look tidy in the panel .
    I always cut them and have not had any issues and it dont matter which way the sensor faces just make sure its not touching the bottom of the pipe that its in and dont overtighten the swagelock nut or you will crush the sensor internally and short it out.
    As far as what they are looking at ......superheat
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  8. #8
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    Quote Originally Posted by graham View Post
    ...As far as dont cut to length ??? Do you see an extra 30ft of cable coiled up in the wire harness on a factory untouched unit ???? ...
    you are absolutely correct. they don't leave any extra wire.

    as far as what will happen? probably nothing. TECHNICALLY...there will an error in the readings. but, in practice, you will not be able to measure the difference anyway.

    the reason for changing out both at the same time is to get as accurate a reading as possible since trane is measuring suction superheat by using 2 temperature sensors. with suction superheat as low as 4F, accuracy is important.
    How to make the perfect "Half-Hitch" knot or any other boyscout knot in 3 easy steps...

    1. Remove your meter leads from the meter and very carefully return them to their storage case or bag.
    2. Wait 2 seconds
    3. Very carefully remove your meter leads from their storage place and enjoy your new knot!

  9. #9
    Join Date
    Mar 2007
    Posts
    3,108
    Make sure you note the depth of the sensor. I usually measure it with a tape measure and make a mark on the new ones with a sharpie so I can get it right the first time and close it up quickly.

    The easiest way to change them is on the fly right after a service pumpdown.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  10. #10
    Join Date
    Jun 2009
    Location
    Florida
    Posts
    540
    Quote Originally Posted by cooolguy View Post
    the holes face direction of flow


    Good one, mate!
    Low Pressure Forever!

    If you know heavy metal, you can work anywhere-Dave Andreson

    Anchors Aweigh my boys, Anchors Aweigh!
    Farewell to foreign shores, We sail at break of day. Through our last night on shore, Drink to the foam. Until we meet once more. Here's wishing you a happy voyage home!

  11. #11
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,443
    Quote Originally Posted by BergerMech Rob View Post
    ...The easiest way to change them is on the fly right after a service pumpdown.
    isn't that a little 'illegal'?
    How to make the perfect "Half-Hitch" knot or any other boyscout knot in 3 easy steps...

    1. Remove your meter leads from the meter and very carefully return them to their storage case or bag.
    2. Wait 2 seconds
    3. Very carefully remove your meter leads from their storage place and enjoy your new knot!

  12. #12
    Join Date
    Mar 2007
    Posts
    3,108
    Quote Originally Posted by jayguy View Post
    isn't that a little 'illegal'?
    No, that's what I call "de minimus". I'm doing my part - allow me to explain. By not pumping the system down and transferring the remaining refrigerant to the condenser, I am not introducing non-condensables into the system, and subsequently contaminating the refrigerant, thus decreasing the amount of viable refrigerant that can be reclaimed when production stops.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  13. #13
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,443
    Quote Originally Posted by BergerMech Rob View Post
    No, that's what I call "de minimus". I'm doing my part - allow me to explain. By not pumping the system down and transferring the remaining refrigerant to the condenser, I am not introducing non-condensables into the system, and subsequently contaminating the refrigerant, thus decreasing the amount of viable refrigerant that can be reclaimed when production stops.
    that is how i do it.
    How to make the perfect "Half-Hitch" knot or any other boyscout knot in 3 easy steps...

    1. Remove your meter leads from the meter and very carefully return them to their storage case or bag.
    2. Wait 2 seconds
    3. Very carefully remove your meter leads from their storage place and enjoy your new knot!

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