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  1. #1
    Join Date
    Sep 2012
    Posts
    14

    Rheem Criterion II-Insufficient Airflow

    A new motor fan and control card has been installed in my Rheem Criterion II. The blower speed is much too low in all three modes (fan on, heat and cool). The contractor who did the repair tried many different settings in many different scenarios (Hi, Med High, Med Low, Low). High and medium high are barely there and low is almost no flow at all. The person doing the work was baffled. The contractor is coming back next week to try again to resolve the issue.

    I want to be "literate" in this particular problem so that I can evaluate if the contractor is doing the right things to resolve the problem. If not, I'll have to go with someone else. In that case, I'd want to ask the right questions of the new candidate to know if they have any better chance of success.

    I think I understand how things work pretty well. You would want to test if the right voltage is being supplied to the motor, you would want to check the run capacitor with the right diagnostic tool. Failing finding a root cause in either of those two things, what would be the logical next steps after that?

    Thanks

  2. #2
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,156
    Could be blocked or disconnected ductwork. Could be a blocked/dirty A-coil. The tech should also measure blower motor amps.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,902
    Motor spinning backwards?

  4. #4
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,156
    Quote Originally Posted by BaldLoonie View Post
    Motor spinning backwards?
    Makes sense, especially since a new motor was just installed.

  5. #5
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,883
    Lost my post & didn't have it saved. Posted in error a prior post that was saved.
    ----------------------------------------------

    First, the Tech has to determine whether it's an electrical problem or an air flow problem; like a blocked A-Coil.
    Last edited by udarrell; 09-02-2012 at 10:36 AM. Reason: Lost the post I has ready, due to an update on my browser!

  6. #6
    Join Date
    Sep 2012
    Posts
    14
    Im pretty sure its turning in the right direction....just very lethargically. Some air is coming up through the vents when on cool and heat. Not much though.

  7. #7
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,401
    If running backward it will blow some but not much, as you are describing.

  8. #8
    Join Date
    Sep 2012
    Posts
    14
    Heh...interesting. I just presumed that it would be sucking in air like a return vent does. I'll make sure that is checked too.

  9. #9
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,608
    Coming back next week ! that would not be acceptable cant beleive he could not find the problem while there . Should have pulled the blower back out and looked through the heat exchanger at the evap coil as im believe it is a 80 percent furnace. Before the furnace quit blowing air was it working fine and then just quit
    We really need change now

  10. #10
    Join Date
    Sep 2012
    Posts
    14
    Yes I was happy with how it was working. This same low airflow situation happened immediately after AC was added to the system in May. It took a while for the tech to resolve it, but eventually he did.

  11. #11
    Join Date
    Sep 2012
    Posts
    14
    PS,., I did notice unusual vibration immediately before the failure.

  12. #12
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,608
    Could be a bad blower wheel ,the hub may have spun loose
    We really need change now

  13. #13
    Join Date
    Sep 2012
    Posts
    14
    So the contractor says nothing is wrong with the motor (all the tests as above have been performed.

    The reason why we are having the problem is because the airflow is restricted by the A/C coil which was added in May in combination with the fact that the furnace is way oversized (125000btu). This leads to the overheat condition.

    Clearly, I am in a bad spot here. What's the right way out of it?

    I presume replacing the furnace with one that is properly sized is the only answer. How would this remedy the problem?

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