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  1. #1
    Join Date
    Dec 2012
    Posts
    7

    Heat Pump Frosting Question

    Hello,

    I am purchasing a new home that has a Heil heat pump unit (International Comfort Products Corp).

    Inside Unit Model #: EF16J2200A2
    Inside Unit Serial #: L0208 57612

    Outside Unit Model #: HHP036AKA1
    Outside Unit Serial #: L0207 96634


    During the inspection phase, I had the unit inspected by a local HVAC company because I had concerns with the outside unit being frosted over during the entire 6 hour home inspection (it was about 30 degrees outside and the unit is on the East side of the house). The HVAC tech determined that the defrost board was shot and needed replaced. He tested the reversing valve by placing the system in AC mode and feeling the line set. The seller paid for the defrost board replacement and the HVAC tech said that defrost was now working. I went to check on the unit myself this morning (28 degrees with an overnight low of 26) and the unit was completely frosted. I have had heat pumps before (a 15 year old Bryant HP - replaced 2 years ago with a Gooodman HP) and did quite a bit of research on how heat pumps work, etc, so I understand about some frosting and that different units will have different amounts of frost build up. However, my gut just tells me that something isn't quite right. Both of my previous HP units never get more than a very thin coating of frost. Nothing even close to what I see on the Heil unit. Any thoughts on Heil and frost build up? I have attached pictures of the outside unit as it was this morning (hopefully they show up).

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  2. #2
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    5,821
    Have it checked again.......might have reversing problem ....hopefully not as it not a easy repair.

    Could be not wired correct or have a defrost sensor problem which would be a easier repair.

  3. #3
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    1,747
    Did they check the charge, low charge can cause them to freeze faster. It could also be if the new board is timed the timing may be sset to long. I know you said that it was around 30* but how much moisture was in the air i.e foggy, drizzle, desert dry, etc., as that will affect how fast and much frost builds. Normally frost should not extend past the cabinet, screen, grill ...

  4. #4
    Join Date
    Jan 2008
    Location
    Texas
    Posts
    1,383
    Could be several things but I agree with sbkold, defrost thermostat issue.

  5. #5
    Join Date
    Dec 2012
    Posts
    7
    Thanks for the quick replies. The tech did not check the charge that I could see. I assume he would need to connect a gauge to the line set, and I did not see him do that. He attempted to jumper the test leads on the defrost board and the unit didn't go into defrost, so his diagnosis was that it needed a new defrost board. He did put the unit into AC mode, came back outside and put his hand on the line set and said the reversing valve was working, so a new defrost board was the way to go.

    The air this morning was somewhat dry (no fog or drizzle). I live in Indiana, and I had little to no scraping to do on my car windshield this morning.

    So, based on your responses the unit shouldn't frost up this much and something is still wrong. Sounds like another call to have it looked at. Thanks again everyone for the responses.

  6. #6
    Join Date
    Jun 2007
    Location
    Greenwood Indiana (Indianapolis)
    Posts
    420
    The even frosting is an indication the charge is good. Its probably the defrost thermostat.
    As iron sharpens iron so one man sharpens another Proverbs 27:17 NIV84

  7. #7
    Join Date
    Dec 2012
    Posts
    7
    When he was looking at the test jumpers on the defrost board, I did see a jumper for 30, 60, 90 and it was set to 60. Does that mean that it would defrost every 60 minutes regardless of temp? Would a defrost thermostat come into play for a system that is hard set on a defrost time? Sorry, I might be way off base...just trying to spitball.

  8. #8
    Join Date
    Jan 2005
    Location
    Emerald Coast
    Posts
    924
    .

    Do the Tech a favor and switch over to your back up heat and allow the HP to
    thaw out before anyone gets there to troubleshoot this unit.
    ..
    Do not attempt vast projects with
    half vast experience and ideas.
    ...

  9. #9
    Join Date
    Jun 2007
    Location
    Greenwood Indiana (Indianapolis)
    Posts
    420
    Quote Originally Posted by superheatsleuth View Post
    .

    Do the Tech a favor and switch over to your back up heat and allow the HP to
    thaw out before anyone gets there to troubleshoot this unit.
    ..
    yes, turn to emergency switch at thermostat the 30/60/90 is a timer, but the defrost stat has to be cold, so in ther words, its the timer and temperature.
    As iron sharpens iron so one man sharpens another Proverbs 27:17 NIV84

  10. #10
    Join Date
    Dec 2012
    Posts
    7
    Thanks for the help guys and thanks for the clarification on the thermostat. I'm not the home owner yet, but I will let the seller know about getting the HP thawed out before the tech arrives. Hopefully I can report back with what we find out.

  11. #11
    Join Date
    Dec 2012
    Posts
    7
    I spoke with the technician that replaced the defrost board to see if there was anything else that we could troubleshoot as the unit is still frosting up. He said "not really". I asked about the defrost thermostat to see if maybe it could be causing a problem - he said that everything to do with defrost was on the board and that the unit will go into defrost how ever many minutes the jumper is set for regardless of any other temps. He couldn't remember what the timer was set for, but said that we could try making it cycle more often. He said charge could be low, but his temperature readings did not indicate low charge (not sure what temperature readings he is talking about). My gut tells me the unit should not be frosting up this much, but a reputable company is telling me there is nothing wrong. Any further insights on this issue? Is it true that some units will not have the defrost thermostat? I believe the unit to be about 10 years old, so perhaps it is too old to have any technology other than 30 60 90 defrost options. By the way, I went back and took another picture later that day (first round of pictures in original post were taken at about 6:30 - I went back at around 5). The high for the day was 48 F and temp at time of these pictures was 46 F. Thanks again for your help. My fear is that I concede this negotiation point with the seller, only to have to buy a new HP unit right after buying the house.

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  12. #12
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,383
    Your technician is just plain wrong. The defrost thermostat clips on the distribution tubes for the outdoor coil and connects to the defrost board with two small wires. ICP had some bad defrost sensors. If the defrost sensor does not tell the board that the coil is cold then it will not initiate a defrost cycle.
    The good news is that it is easy to test and the part is inexpensive. Have a different technician (a capable one) test and probably replace the sensor once he confirms it is bad.
    The unit is not so old as to require replacement.

  13. #13
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,383
    There is no need to defrost the unit first. If it is frosted then the conditions are right to check the sensor.
    Also, regarding the technician saying that the unit defrosts by the clock is incorrect. The timer on the defrost board monitors operating time, not clock time. The board checks the sensor status every interval of 30/60/90 minutes.

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