Results 1 to 11 of 11
  1. #1

    Trane Heat Pump AC fan speed seems low

    I have a 3.5ton Trane heat pump that has been set for the "Enhanced" ICM fan control in cooling mode. This year I think that the fan has not been blowing as hard in cooling mode. I had my service company come out and basically they changed the DIP switches so it always blows full speed when cooling. The DIP switch combination they used isn't listed in the air handler installation instructions and they seemed to spend a fair amount of time reading the instructions, so I'm not confident that they are that familiar with this system (it was installed in 2003 by them).

    My question is how can I determine if the ICM fan speed control is working properly? I have set the thermostat at 65 degrees for more than 20 minutes to see if the fan eventually kicked in high gear but it never jumped up. According to the installers guide, the enhanced mode should run at 50% for one minute for "fast coil cooling", then up to 7.5 minutes for "dehumify" and finally 100% "if necessary, so 20 minutes on a hot day should've been sufficient.

    Other info: in heating mode, the fan blows much harder (the installer guide says it should blow about 450 CFM/ton according to the original DIP switch settings). In cooling mode with the dip settings the servicer used, the fan also blows much harder. There is no humidstat in this system and it has a Chronotherm III.

    Thanks for your help

    Pete

  2. #2
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658
    Quote Originally Posted by dogbert2521 View Post
    I have a 3.5ton Trane heat pump that has been set for the "Enhanced" ICM fan control in cooling mode. This year I think that the fan has not been blowing as hard in cooling mode. I had my service company come out and basically they changed the DIP switches so it always blows full speed when cooling. The DIP switch combination they used isn't listed in the air handler installation instructions and they seemed to spend a fair amount of time reading the instructions, so I'm not confident that they are that familiar with this system (it was installed in 2003 by them).

    My question is how can I determine if the ICM fan speed control is working properly? I have set the thermostat at 65 degrees for more than 20 minutes to see if the fan eventually kicked in high gear but it never jumped up. According to the installers guide, the enhanced mode should run at 50% for one minute for "fast coil cooling", then up to 7.5 minutes for "dehumify" and finally 100% "if necessary, so 20 minutes on a hot day should've been sufficient.

    Other info: in heating mode, the fan blows much harder (the installer guide says it should blow about 450 CFM/ton according to the original DIP switch settings). In cooling mode with the dip settings the servicer used, the fan also blows much harder. There is no humidstat in this system and it has a Chronotherm III.

    Thanks for your help

    Pete
    the dip switch settings chart should be on the blower housing or door of the unit. advise calling someone else to fix unit, seems like that compamy dont know jack, Dude!!

  3. #3
    Join Date
    Sep 2007
    Location
    KY
    Posts
    79

    ???

    You are saying that no settings were changed but you seem to notice less airflow?

    If this is correct I would start checking other places rather than dip switch settings.

    Check or have pro check supply and return ducts for damage, loose insulation
    make sure filter is clean. blower wheel and evap coil also.

    Is it a 90% furnace? if so maybe secondary heat exc is dirty.

    You may have issues with your ecm, but start with something more simple.

  4. #4
    Quote Originally Posted by chlosum View Post
    You are saying that no settings were changed but you seem to notice less airflow?

    If this is correct I would start checking other places rather than dip switch settings.

    Check or have pro check supply and return ducts for damage, loose insulation
    make sure filter is clean. blower wheel and evap coil also.

    Is it a 90% furnace? if so maybe secondary heat exc is dirty.

    You may have issues with your ecm, but start with something more simple.
    Thanks for the reply.

    Yes, that is what I'm saying. On the heat setting, and in cooling mode with the DIP switch change that they made, the blower came on full strength (or at least a lot stronger than what it was on cooling before the DIP change). This is what leads me to think that the controller board may be the problem.

    This is a heat-pump with electric backup, no gas or oil. The coil is clean and the blower seems clean too (along w/ the electric air cleaner).

    Any suggestions on how to do a quick check the ECM short of replacement or calling in another tech? I'm all for paying someone who knows what they're doing, but so far I think I'm 0 for 1 in that department. This unit does have an extended warranty but I'm not sure if its backed up by Trane or by the dealer.

  5. #5
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658
    Quote Originally Posted by dogbert2521 View Post
    Thanks for the reply.

    Yes, that is what I'm saying. On the heat setting, and in cooling mode with the DIP switch change that they made, the blower came on full strength (or at least a lot stronger than what it was on cooling before the DIP change). This is what leads me to think that the controller board may be the problem.

    This is a heat-pump with electric backup, no gas or oil. The coil is clean and the blower seems clean too (along w/ the electric air cleaner).

    Any suggestions on how to do a quick check the ECM short of replacement or calling in another tech? I'm all for paying someone who knows what they're doing, but so far I think I'm 0 for 1 in that department. This unit does have an extended warranty but I'm not sure if its backed up by Trane or by the dealer.

    Dude, sounds like the maint. man took off a jumper. In the heat mode, any time W1 is energized the ecm ramps to full capacity regardless of time. Your dips set cfm per ton, tonage on outdoor unit, etc... They probably changed your settings. I recommend you call a different Trane dealer, OR ask the same company for their top qualified tech.. Good luck!!

  6. #6
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,058
    Quote Originally Posted by dogbert2521 View Post
    I have a 3.5ton Trane heat pump that has been set for the "Enhanced" ICM fan control in cooling mode. This year I think that the fan has not been blowing as hard in cooling mode. I had my service company come out and basically they changed the DIP switches so it always blows full speed when cooling. The DIP switch combination they used isn't listed in the air handler installation instructions and they seemed to spend a fair amount of time reading the instructions, so I'm not confident that they are that familiar with this system (it was installed in 2003 by them).

    My question is how can I determine if the ICM fan speed control is working properly? I have set the thermostat at 65 degrees for more than 20 minutes to see if the fan eventually kicked in high gear but it never jumped up. According to the installers guide, the enhanced mode should run at 50% for one minute for "fast coil cooling", then up to 7.5 minutes for "dehumify" and finally 100% "if necessary, so 20 minutes on a hot day should've been sufficient.

    Other info: in heating mode, the fan blows much harder (the installer guide says it should blow about 450 CFM/ton according to the original DIP switch settings). In cooling mode with the dip settings the servicer used, the fan also blows much harder. There is no humidstat in this system and it has a Chronotherm III.

    Thanks for your help

    Pete
    Post your model # and a pic of the dip switches

  7. #7
    Join Date
    May 2008
    Location
    Baker City, OR
    Posts
    14
    Quote Originally Posted by dogbert2521 View Post
    I have a 3.5ton Trane heat pump that has been set for the "Enhanced" ICM fan control in cooling mode. This year I think that the fan has not been blowing as hard in cooling mode. I had my service company come out and basically they changed the DIP switches so it always blows full speed when cooling. The DIP switch combination they used isn't listed in the air handler installation instructions and they seemed to spend a fair amount of time reading the instructions, so I'm not confident that they are that familiar with this system (it was installed in 2003 by them).

    My question is how can I determine if the ICM fan speed control is working properly? I have set the thermostat at 65 degrees for more than 20 minutes to see if the fan eventually kicked in high gear but it never jumped up. According to the installers guide, the enhanced mode should run at 50% for one minute for "fast coil cooling", then up to 7.5 minutes for "dehumify" and finally 100% "if necessary, so 20 minutes on a hot day should've been sufficient.

    Other info: in heating mode, the fan blows much harder (the installer guide says it should blow about 450 CFM/ton according to the original DIP switch settings). In cooling mode with the dip settings the servicer used, the fan also blows much harder. There is no humidstat in this system and it has a Chronotherm III.

    Thanks for your help

    Pete
    The first thing I always do when talking about Ecm Motors is that they typically have a static pressure sensor in the furnace. THat means that when you have a restriction of any nature the motor will "know to adjust itself". So checking the ductwork, and filter is a good place to start then consider the possibility of a board or sensor failure. Toggling dip switches typically bypasses the static sensor so the unit will run with separate speeds with each mode.Consider having a static pressure test done in order to see what the unit "sees". Ultimately you will have to have a tech do this so my best advise is to ask around and find the best dealer or if it is the same company the best tech to look at it. (BTW looking in the instruction manual does not exactly mean they don't know what they are doing!)

  8. #8
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,058
    There is not a static pressure sensor in the furnace or air handler it is a computer program in the module on the motor, it does not read static pressure.

  9. #9
    Thanks for the ideas, I appreciate it.

  10. #10
    Join Date
    May 2008
    Location
    Baker City, OR
    Posts
    14
    Quote Originally Posted by second opinion View Post
    There is not a static pressure sensor in the furnace or air handler it is a computer program in the module on the motor, it does not read static pressure.
    THe units I sell DO Have them. Just throwing out ideas. Either way the dip switches bypass the normal function of the unit.

  11. #11
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658
    Quote Originally Posted by crzymtrbiker View Post
    THe units I sell DO Have them. Just throwing out ideas. Either way the dip switches bypass the normal function of the unit.

    you stick to the mountain bikes, we'll do the hvac!!!

    dip switches don't bypass anything, they SET the blower operation
    (depending on the call, and the way the unit is wired on the low voltage terminal board)

    if the "O" terminal is not wired or energized, the unit will not enter enhanced mode.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event