Carrier Infinity system - shows incorrect temp and not cooling properly

Discussion in 'HVAC Heating & Cooling' started by Pickngrin, Aug 6, 2011.

  1. Pickngrin

    Pickngrin New Member

    Messages:
    54
    Location:
    Massachusetts
    We just purchased a home that has a Carrier Infinity system. We were in the house yesterday and the thermostat read 80 degrees, although it did not feel quite that warm in the house. I manually set the temp to 74 degrees and even though I could hear the fan running and air blowing, the house did not cool off significantly several hours later. I stuck a dial thermometer in the air vent and it read 72 degrees. Should the temp of the conditioned air been lower? I realize that there are many variables and that no one can give me a definitive answer, but I just wanted to ask what things I can check out before calling an HVAC tech. I do know that I have to change the filter (during the inspection, the inspector told me that, but he was unable to test the ac system because the outdoor temp was low at the time). All other systems in the house have clearly been well maintained and the sellers said that the ac system was working properly last summer.
    Any suggestions?

    Thanks.
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    The air coming out of the vent should at least 10º and probably closer to 20º cooler than the air at the return vent. Dirty filters, dirty coils, indoors and out, and duct leaks in the attic, if you have such, are all candidates.
  3. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    If it still has trouble after the filter is changed, then there is a fair chance that it is low on refrigerant. I lived in a house for 12 years that required a refrigerant top off once/year.

    When you said that fan was running and air blowing, did you also verify that the compressor and condenser fan outside were running as well? Sometimes these do not come on when they should. (It sounds like yours did because of the temp difference.) I've had trouble with relays/contactors before in 2-different homes and they were replaced...and in a third home I had to bang on the AC's electrical box a bit to get things running--had some mud dauber issues apparently.

    One other thing worth checking: new batteries in the thermostat can sometimes work wonders. I've had older thermostats act really funny when the batteries were low and they had no low battery indicator. Either the system (heat or cool) would run all the time, or not at all.
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
  5. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    If was legal at the time, and may still be today depending on loss rate. Wasn't my choice as to whether to find the leak and fix it, the owner didn't mind spending the money for the top off each year rather than replace the system. The HVAC guy and I both recommended replacing it, but freon wasn't that pricey yet.

    Rules have gotten stricter on this (and I'm all for that) but as I recall even 8 years ago it could still be charged as long as it wasn't exceeding some annual threshhold.
  6. Pickngrin

    Pickngrin New Member

    Messages:
    54
    Location:
    Massachusetts
    Thanks for the responses. I changed the filter and the ac performance appears unchanged. The compressor fan outside was indeed turning on. Neither of the two metal lines coming out of the compressor felt cold to the touch. Would that point to a low refrigerant level? I will be calling an HVAC tech to take a look and of course I do not want to get hosed.
  7. Jack_Mason

    Jack_Mason HVAC Expert

    Messages:
    6
    Location:
    new york, ny
    I would recommend that you talk to a couple of HVAC contractors before pulling the trigger on a servicing / repair decision. You can use Service Magic or Quality Smith to find pre-qualified contractors and get free estimates. Some folks will give you a good deal of free information. Given your description of the problem and my experience with Carrier Infinity systems, I would strongly consider the possibility that you have a refrigerant leak. Their evaporator coils have been known to have leaks. In that case, simply adding more refrigerant would not solve the issue.
  8. Pickngrin

    Pickngrin New Member

    Messages:
    54
    Location:
    Massachusetts
    Thanks for the input. Fortunately, the HVAC company we called (who the previous owners of the house used) wound up being a stand-up operation. The technician found a loose duct in the attic (turns out the contractor who laid insulation up there accidentally disconnected a duct) and didn't even recommend further work unless we continued to have problems. After the duct was reconnected, we realized that there still was not enough of a temperature differential between the vent and return temps. A tech came out today and did a dye test (he offered to either top up the system -- I know, I know, this is not recommended --- or do the leak test) and added some refrigerant. It's blowing colder now and hopefully we'll soon know if there's a leak. The good news is that we learned that our system has a 10 year warranty, with 5 years remaining (on parts).
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