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Thread: AC Problems

  1. #1
    Join Date
    Jun 2006
    Posts
    7
    I have a Honeywell pc8900a thermostat with a Rheem blower. The thermo is set on four different settings (wake, leave, return & sleep). Between return (6pm) and sleep(8pm) mode the ac begins to blow warm air. I turn the system unit off via the thermo. Wait approx, 5-10 minutes and turn it back on. Then it begins to blow cold air and no problems.

    Had a tech come out. He did all of the normal maintenance. Still between those two modes the ac blows warm air.

    Any ideas??

  2. #2
    Join Date
    Dec 2005
    Posts
    4,008
    If your sure its programmed correctly and that is the only time you are having a problem, I would say the thermostat is defective.

    When you had the tech do the maintenance, what did he say about it?

  3. #3
    Join Date
    Jun 2006
    Posts
    7
    Let me first say the house and ac equipment are only 4yrs old.

    He actual came out twice. The first time he added freon and did all the measurements. Everything look good. But still the problem. Called him out a second time. Again everyhing checked out, but said it might be the thermostat or controller. He wanted to install a new system (rewire). Told him I wanted to think about it..


  4. #4
    Join Date
    Mar 2004
    Posts
    1,042
    Is the outdoor unit still running during that time interval?

    If so, the thermostat is doing all it can do. It could be that the system isn't running all that well and that at the time of day when pressures are highest (hot outside, hot inside from being set back) that the system goes out on the high pressure switch... or that the compressor overheats and shuts off on thermal overload for awhile.


  5. #5
    Join Date
    Jun 2006
    Posts
    7
    Between 6-8pm, the unit outside is running and blowing warm air. During that time frame I would turn the system unit off via the thermo, wait a few minutes and then turn it back on. Then it begins to work.

  6. #6
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    It's gotta be the stat. Only in that time period? A good tech will notice that right off the bat and at least swap em out for a check. Call him back out and have him do it.

  7. #7
    The most probable cause is the electronics of the themostat, as your manual "ON" works fine to cool the air, but not the programmed one.

    Did you tell your contractor to try a different thermostat?

  8. #8
    Join Date
    Jun 2006
    Posts
    7
    I think "wyounger" has it right because last night (Dallas, Tx.) we had an overcast and lightly cooler day/night and it worked fine.

    Is this a major cost to repair??


  9. #9
    Join Date
    Jul 2002
    Posts
    962
    yep, T-stat can't be the problem if the unit is turning on.

  10. #10
    Join Date
    Jun 2006
    Location
    Michigan
    Posts
    963
    If you want to rule out the thermostat problem just set it on "hold" and see if the problem still occurs. Sounds to me like the earlier post about internal overload would be more likely, this time is probably when the unit has been working hardest so compressor is overheating. Could be low on charge causing too warm suction line.

  11. #11
    Join Date
    Jun 2006
    Posts
    7
    Thanks for all of your help. Have a tech coming out this Friday. Will let you know what he finds out.

    Thanks Again!

  12. #12
    Join Date
    Jun 2006
    Posts
    7
    Here is what the Tech said "All style coil has a bad TXV(?). 30 suction, 225 head. Tried to add freon, would not raise suction pressure. Checked temp across drier, (OK). He is recommending a new coli which will run about $1750.

    Does this sound like it will eliminate my problems?


  13. #13
    Join Date
    Dec 2005
    Posts
    4,008
    Originally posted by ajslas00
    Here is what the Tech said "All style coil has a bad TXV(?). 30 suction, 225 head. Tried to add freon, would not raise suction pressure. Checked temp across drier, (OK). He is recommending a new coli which will run about $1750.

    Does this sound like it will eliminate my problems?





    From what your tech. said it sounds right. Without being there we can't tell for sure. But with the symptoms you describe that definetly could be the problem. We are not supposed to discuss pricing on this forum.

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