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  1. #1

    Problems with Old Comfortmaker Evap Coil

    I am completely baffled and my customer cant afford a new air handler, looking for any advice:
    Location:Phoenix, AZ
    Split System Heat Pump
    Outside condensor: 3.5 ton - 13 seer Carrier - all tested good - no leaks
    Air Handler - Comfortmaker (orig to house) 4 ton (I believe) with .081 orifice. The orifice is connected to a 3/8" line with a T that feeds, what I believe to be a check valve (for heating) that ties into a 1/2" line that is connected to all 4 coil ports. The other portion of the 3/8" enters a capillary bulb (distributor) that feeds the 4 lines to the coil.
    Problem:Very little cooling, 8 degrees at closest supply vent to return.

    Coil is an A style coil installed horizontally. Top of coil at return plenum, as per installation instructions found in air handler.

    I have never seen this kind of piping on an evap coil, but something is not operating correctly. My first suspicion was the in line check valve for heating was not sealing, so I cut and sealed the lines to take this out of the equation. The result was not measureable in the pressures or the amount of cooling in the coil. Low side pressure at 85 degrees external, 75 degrees internal was 50lbs and high side pressure of 200.

    My suspicion now is that there is a plug, obstruction, in the capillary lines themselves. I tried a nitrogen purge from both directions and there is flow, but I cannot determine whether all four capillary lines are unplugged.

    We filled the system with the 11lbs of freon, 10.88 on the panel and line set is only 12 ft long, the result was almost no cooling at the coil. We started adding freon in 1lb increments and at 18lbs the coil is still only 1/3 cold.

    If anyone has run into this before and worked through it, please pass on your thoughts. The customer has been out of work for 6 months and they are struggling, so I want to try and help them out if possible. Thanks for any help.

  2. #2
    Have you verified the correct fan speed, CFM, no restrictions to airflow?
    What was your superheat and subcool on the system after adding the charge?

  3. #3
    Join Date
    Jan 2007
    Location
    NE OHIO
    Posts
    778
    restriction=frost

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