wall unit AC question

Discussion in 'HVAC Heating & Cooling' started by chaoster, Apr 30, 2008.

  1. chaoster

    chaoster New Member

    Messages:
    42
    I have a 23,000 BTU friedrich wall unit for my first floor. Last summer I had a problem with the inside fins (behind the filter) icing up. Does anyone know is wrong? do I need to call a repairman? TIA
  2. BigLou

    BigLou New Member

    Messages:
    138
    yeah I think know whats wrong. you failed to size the unit properly. Bigger is not better when it comes to hvac equipment. you either need a smaller unit or more warm air getting to that unit

    good luck

    Lou
  3. PEW

    PEW DIY Senior Member

    Messages:
    487
    Did it ever work properly? If it did, be sure you filter is clean, and it could also be low on freon.
  4. chaoster

    chaoster New Member

    Messages:
    42
    Yes it worked fine up till 2 years ago. The unit is about 7 or 8 years old.
  5. PEW

    PEW DIY Senior Member

    Messages:
    487
    If the filter is clean, and the evap coil is clean, you are probably low on freon.

    Check the evaporator coil, they can collect dust reducing air flow.
  6. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    I had that problem with a cheep window unit. I found I could make it work by moving the temp sensor so it touched the heat exchanger. The result is that it cycled on and off as needed.

    Strangely bigger is better as long as the freon charge is high enough.

    PS: we should to switch to R290, R-600, R-600a, or one of the other less polluting freon types. R290 is great since you can use the old style gauges and even vent it.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,240
    Location:
    Cave Creek, Arizona
    Sometimes

    Strangely bigger is better as long as the freon charge is high enough.

    Only in low humidity areas. Otherwise the units shuts down too fast to perform its dehumidification function properly.
  8. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Well, I am not an HVAC tech, but I keep my ear to the ground. I have never heard of any of the refrigerant types you mentioned. It seems cars and smaller A/C's are using R134, and unitary products including typical split central A/C are moving towards R 410. In any event, by 2010, just about 18 months from now, it will not be legal to manufacture new equipment using R22. You will stil be able to repair older equipment, and until I think at least 2020, service contractors will be able to purchase R22 for use in repairs. The price of R22 has already jumped up, almost double what it was a year ago, and will continue to go up as only recylced stuff, and no virgin refrigerant, will be available.

    I know that just the switch up to 13 SEER 2 years ago has caused a lot of trouble, as "shade tree" HVAC techs don't have the skill and training they need to deal with those issues. This will be even worse with the change up to the new refrigerants.

    If a young person was looking for a good career, an investement in a couple of years of HVAC trade school is looking good right now. Same is true for the auto repair business......"shade tree mechanics" cannot deal with today's cars. An educated, ASE certified tech will be able to make a lot of money.
  9. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    I plan on having this one piece of R22 equipment converted to R290. It's actually a quite simple process since R290 has the same pressure curves and is compatible with the oil used in R22 systems. There is a slight difference in the viscosity and therefore it's recommended to change the restrictor tube for maximum efficiency, but that's not really critical.

    I just don't see any advantage to R410 since it's a nasty long term greenhouse gas and as such has to be recovered just like R22.

    R290 on the other hand is gaining popularity in Europe.
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