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York furnace slow fan speed

emerald
emerald Member Posts: 9
in A-C, Heat Pumps & Refrigeration

Hello group. New to using fourm. Have a york 95% furnace that runs 600 cfm when in cooling mode. Heat mode ramps up normal. 2 units in house doing same thing. I thought control board at first but what are the chances of both going. Any thoughts would be greatly appreciated.

Comments

  • ratio
    ratio Member Posts: 4,104

    What's the cooling speed set to?

    It usually takes me a half-hour to figure out the DIP switch settings each time, I don't play with them often enough.

  • emerald
    emerald Member Posts: 9

    No Dip switch on this board. I am unfamiliar with york equipment and this board.

  • mattmia2
    mattmia2 Member Posts: 13,912

    did it ever work?

  • emerald
    emerald Member Posts: 9

    Good question. Last year it froze up and flooded the bedroom below. I was called in the fall for no heat. After checking the motor I Determined the board was bad. Replaced board and heat was operating. This was in November so I didn't run the ac. This call I don't believe the ac worked at before I arrived. I never worked on 2nd unit in basement. While there today I went to basement and found the unit operating same manner. Cfm light is blinking 6 times calling for 600 cfm. Units are both 12 yo and in good condition otherwise.

  • mattmia2
    mattmia2 Member Posts: 13,912

    is y from the t-stat connected to the control board(or is it a communicating t-stat)? is it an ecm motor or is the speed set with tap connections on the control board?

    essentially rtfm

    HVACNUT
  • emerald
    emerald Member Posts: 9

    Yes the condenser comes on with call. Ecm tested and runs. Fan runs properly in heat mode.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,892
    edited June 26

    Need the model number of the 95% York furnace so I can look up the necessary settings to make the fan operate at the proper speed needed for the matching condensing unit.  If you have a 1.5 ton condenser, then 600 is the correct fan speed. if you have a 3 ton condenser then you want to use 1200 cfm. or thereabouts.    

    If the fan operates at a higher speed for heat, then there has to be a way to adjust the cooling fan speed based on the size of the outdoor unit.

    The York 95% furnace can be a single stage gas valve or a two stage gas valve or a variable input gas valve. Each of those furnaces has a different model number and therefore a different instruction manual and perhaps a different fan speed controller. There are also PSC motors and ECM motors that will be adjusted differently. I assume that you have the variable speed ECM fan motor by the previous statements you made, but the model number will tell all that is needed.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • mattmia2
    mattmia2 Member Posts: 13,912
    https://forum.heatinghelp.com/discussion/comment/1858726#Comment_1858726

    that isn't what i asked. i asked if y from the t-stat was connected to the control board(or is otherwise made to do a high fan call on y or g, newer air handlers will just do low fan with g)

  • emerald
    emerald Member Posts: 9
    edited June 26

    Mdl Tm9v100c16 yes ecm motor. 4 ton unit. So I know I should be getting 1600 cfm .

  • emerald
    emerald Member Posts: 9

    Yes y is connected to the control board on from thermostat.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,892
    edited June 26

    https://forum.heatinghelp.com/discussion/comment/1858748#Comment_1858748

    So you are not using the communicating thermostat ABCD. but you are using the Legacy thermostat with R W1 W2 G Y1 Y2 C terminals

    Are you using a 2 stage thermostat?

    Are you using a 2 stage condensing unit?

    You might want to set the fan based on these instructions: From page 33 of the manual.

    Screenshot 2025-06-26 at 3.58.00 PM.png

    There are more details in this manual: TM9V C Series I believe the York and the Johnson are identical units

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • emerald
    emerald Member Posts: 9

    Thank you for the information ed. No booklet left from the installer. This is very helpful and I am going back tomorrow. I will let you know how I make out. Thanks again

    EdTheHeaterMan
  • emerald
    emerald Member Posts: 9

    Finally fixed. Upon arrival this morning unit was running correctly. I watched for a couple cycles and then slow fan again and no condenser. I checked voltage and only had 19 on y. Ran new thermostat wire and and problem solved. Thank you for all the information provided. Enjoy your summer

    EdTheHeaterManmattmia2
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,892

    Another happy customer!

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • ratio
    ratio Member Posts: 4,104

    Two units, both with defective stat wires? That both failed in the same manner?

    I don't doubt you, but that's really strange. The failure mode is really strange, too. Doubly strange. Quadruply strange??

    Defective stat wire? Overly excited helper stapling up the wire?

  • emerald
    emerald Member Posts: 9

    Homeowner tells me the units have never worked correctly or consistently since installed. Several freeze ups over the years.

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