(206) 949-5683, Top Rated Plumber, Seattle
Page 2 of 3 FirstFirst 123 LastLast
Results 16 to 30 of 38

Thread: A/C start-up intermittent start up issue

  1. #16
    DIY Junior Member jp102's Avatar
    Join Date
    Jul 2011
    Location
    Michigan
    Posts
    20

    Default

    DonL - I have SW1-5 ans SW1-6 set to ON/OFF (profile B) which gives 1600 CFM HI, 1200 CFM low which I believe matches the 4 ton AC unit specs.

    Yes I can hear the blower changing speeds.

    Question - when the AC frezes up, does or should the blower shutdown? Should the entire system shutdown when it freezes?

  2. #17
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,645

    Default

    It should be set for 1600, on cooling.

    And the whole system would shut down, not just the blower.

    You may want to set for 1600. Then run the t-stat on auto.


    DonL
    Last edited by DonL; 07-13-2011 at 04:47 AM.
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  3. #18
    DIY Junior Member jp102's Avatar
    Join Date
    Jul 2011
    Location
    Michigan
    Posts
    20

    Default

    Thanks. Maybe I'm chasing the wrong problem. I've been trying to figure out why the blower isn't starting, maybe I should be figuring out why the AC unit isn't shutting down when it freezes. Obviously I need to figure out why it freezes, but that might be another issue. Can you share any thoughts on the shutdown circuit of the system if it detects a freeze?

  4. #19
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,645

    Default

    The blower could be running and it could be hard to tell, because when it freezes up there is no place for the air to go.

    But for a 4 ton then you want to run the blower at least 1600, or it could Ice up.

    As for the shutdown, I am not sure if that part works on the air side.
    Could only be for heating.

    With it being two different brands, that is hard to tell, if the controller even knows that it is iced up.

    Wish I could have the answer, but I am not for certain.


    I would start by upping the air flow, and your problem may be solved.


    Enjoy your day.


    DonL
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  5. #20
    DIY Senior Member Runs with bison's Avatar
    Join Date
    Aug 2009
    Location
    Midwest
    Posts
    892

    Default

    Quote Originally Posted by jp102 View Post
    DonL - I have SW1-5 ans SW1-6 set to ON/OFF (profile B) which gives 1600 CFM HI, 1200 CFM low which I believe matches the 4 ton AC unit specs.

    Yes I can hear the blower changing speeds.

    Question - when the AC frezes up, does or should the blower shutdown? Should the entire system shutdown when it freezes?
    I have the same 9 month old Ruud (same model number and equipment as Rheem). Check your flows on the ECM blower by reading the blinking red light in the little view port on the air handler (one blink = 100 CFM per p. 54 of manual.) This isn't the actual flow but represents the target speed call by the board. Mine is also paired with a 4 ton AC (new Rheem two stage AC.)

    The manual states on p. 47 that the default for these is max flow, profile A, which is 2000/1500 cfm. That is how mine was set up IIRC (I've got notes on dip switch positions...but have misplaced them.) I've since dialed back with the optimization switch set (which is noted wrong in the manual per my recollection and testing--the manual is confused and confusing in this section) so that it is running about 1800/1300 to better dehumidify on low stage. I'll take a look at this tonight once we get back below 95 F. I might try setting it to B to see if any problems appear. To do that I'll have to reset the optimization switches to default.

    My furnace also tends to start up a little noisily, haven't noticed the blower making the rumble in summer. I'll take a closer listen tonight. I believe the rumble in winter is from the furnace first firing up as I recall. Something to do with the sealed combustion and ID set up, maybe some baffle rattle. It actually became more noticeable when I had some of the side ports on the furnace blocked off (they weren't originally, but should have been.) There could be some sort of "critical speed" vibration on the blower at the lowest speeds, I suspected that. Since it doesn't stay in that mode more than a few seconds I haven't tried to follow it up.

    At any rate, mine seems to be doing pretty well at cooling so far...while the old one was having trouble and approaching the point of siezing up.

    Note that the default "FAN" circ. setting is very low for the blower if in the "low" setting (around 500-600 CFM I think.) I've reset mine to "high." Our 90k units are not in table for this on page 48. Even "high" is not that high--something like 1200 CFM I think I measured. So if this is being used for the blower speed when the 4 ton is running, it could be having trouble freezing up from low air flow. That could be the case if there is some sort of miswiring.

  6. #21
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,645

    Default

    Quote Originally Posted by Runs with bison View Post
    Note that the default "FAN" circ. setting is very low for the blower if in the "low" setting (around 500-600 CFM I think.) I've reset mine to "high." Our 90k units are not in table for this on page 48. Even "high" is not that high--something like 1200 CFM I think I measured. So if this is being used for the blower speed when the 4 ton is running, it could be having trouble freezing up from low air flow. That could be the case if there is some sort of miswiring.
    Normally you would want the blower to run at 400 CFM per Ton of cooling, So what you are saying makes sense.

    If all the system is a Rheem then the system should shutdown if it did detect a Iced up condition, Or at least increase the blower speed to at least 1600 CFM if it was in a dehumidifier mode and seen the was Icing.

    Normally the compressor would also cut back if it decreases the fan speed and dehumidify on low stage.

    Sounds like the outside unit does not know what the inside unit is doing.

    Could be just a wiring problem between a Rheem and a Carrier, Wiring color code maybe.

    Thank You for your info Runs with bison.


    Enjoy Your Day.


    DonL
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  7. #22
    DIY Senior Member Runs with bison's Avatar
    Join Date
    Aug 2009
    Location
    Midwest
    Posts
    892

    Default

    Quote Originally Posted by DonL View Post
    Sounds like the outside unit does not know what the inside unit is doing.

    Could be just a wiring problem between a Rheem and a Carrier, Wiring color code maybe.

    Thank You for your info Runs with bison.
    You are welcome.

    That's what it sounds like to me too, but since I've never run the wiring or done the controls on HVAC units I can't really take it past that.

    Another thing I would check is the specific jumper for the AC type--SW12 should be set to ON for single stage cooling. Sounds like he's probably already done that.

  8. #23
    DIY Junior Member jp102's Avatar
    Join Date
    Jul 2011
    Location
    Michigan
    Posts
    20

    Default

    Thanks guys. I've re-checked all the settings and configs and they are in agreement with your suggestions. The system runs only on the thermostat, no humidity sensor/control. Also since it is an older AC unit, there are only two wires running to the AC contactor (Y1 and C) so the outside unit is dumb.

    Someone mentioned that the Rheem furnace detects an iced condition, does anyone know how it detects this? Also what does it do once it detects an iced condition; does it shut down blower, can it pull Y1 to low and override the thermostat's call for cooling thus shutting down the outside AC unit?

  9. #24
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,645

    Default

    Good Morning,

    I believe it detects the air flow, and knows something is not correct.

    You should be connecting to Y2.
    On Y1 the blower will only be running on low speed, and will ice up.

    Y2 will turn the compressor off when the blower is not running.


    Enjoy Your Day.


    DonL
    Last edited by DonL; 07-14-2011 at 07:01 AM.
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  10. #25
    DIY Junior Member jp102's Avatar
    Join Date
    Jul 2011
    Location
    Michigan
    Posts
    20

    Default

    Thank you. I'll make the switch tonight

  11. #26
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,645

    Default

    Quote Originally Posted by jp102 View Post
    Thank you. I'll make the switch tonight
    Please let us know how it works for you jp102.

    After you switch over from Y1 to Y2 , I think your system will work a lot better for you.

    Even save you money.


    Have a great day.


    DonL
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  12. #27
    DIY Senior Member Runs with bison's Avatar
    Join Date
    Aug 2009
    Location
    Midwest
    Posts
    892

    Default

    When you make the switch, I really encourage you to count the blinks on the red LED before and after you switch it. The LED blinks periodicaly when running, 1 blink = 100 cfm. The blinks are a little uneven at the start and end of the sequence so I might be off by 1 for the way I count them, but even if I am it makes it easy to compare before and after when changes are made.

    Also, the rumble at start up on circ is definitely still there--seems to continue until it gets up to speed. I tested circ today and counted ~13 blinks on the "high" circ switch setting. That corresponds to the same flow as the 105k furnace in the table on p. 48 (where the 90k furnace is not listed.)

    I've also gone to profile B, 1600 cfm, for my 4 ton AC to improve dehumidification on the low stage air (this will dial it back to 1200 cfm for 2 tons--it defaulted to 1500 cfm in low and I had cut it back 10% before with other switch settings that I've now reverted.) I've confirmed the low and high values with the LED blinks.

  13. #28
    HVACR tech Gary Beach's Avatar
    Join Date
    Jul 2011
    Location
    Nixa, MO
    Posts
    4

    Default

    Quote Originally Posted by jp102 View Post
    DonL - thanks. Some of the replies are getting out of sync so bear with me if it sounds like I'm repeating myself.

    Yes it has operated correctly with the Aprilaire 8466. The 8466 was installed with the furnace and the system has operated from Oct-April last year on heat, May to present on AC. Many, many calls for AC, only failed three times. Always in CIRC mode.

    After I resart, the system continues to operate normally and does not ice up.
    I would try eliminating that April air thermostat. See what that does. "Circulate Fan Mode means that the fan comes on for 10 minutes every 30 minutes for better indoor air quality plus reduces hot and cold spots within your home."
    http://www.aprilaire.com/index.php?z...y=23&item=8466

    I have seen these fail, and be miss-wired, or the setup program could cause this even. Go get an old basic thermostat and wire it in place of the April air. (Eliminate the April air all together for now). See what the A/C does without that.
    Last edited by Gary Beach; 07-16-2011 at 04:00 AM.

  14. #29
    HVACR tech Gary Beach's Avatar
    Join Date
    Jul 2011
    Location
    Nixa, MO
    Posts
    4

    Default

    Quote Originally Posted by jp102 View Post
    Thanks guys. I've re-checked all the settings and configs and they are in agreement with your suggestions. The system runs only on the thermostat, no humidity sensor/control. Also since it is an older AC unit, there are only two wires running to the AC contactor (Y1 and C) so the outside unit is dumb.

    Someone mentioned that the Rheem furnace detects an iced condition, does anyone know how it detects this? Also what does it do once it detects an iced condition; does it shut down blower, can it pull Y1 to low and override the thermostat's call for cooling thus shutting down the outside AC unit?
    Is it a Heat Pump? They detect ice in the Heat Pump mode, but normally not in A/C mode. Not unless it has an airflow switch in the air handler supply duct.

  15. #30
    DIY Junior Member jp102's Avatar
    Join Date
    Jul 2011
    Location
    Michigan
    Posts
    20

    Default

    DonL - was wired to Y2 on control board (Y on thermostat)

    Bison - counted the flashing red led, got 16 flashes = 1600 CFM

    Gary - it's not a heat pump, there is no external sensor in supply duct. I'll try and dig up the old thermostat, replace the Aprilaire and see what happens.

    I still do not understand if a Rheem RGRM 90k will shut down the blower if it detects an iced condition. If anyone knows the answer to this question, please let me know as it will give me an indication of where to troubleshoot. Right now I still do not know if the blower is not starting; hence causing the iceup. Or if the iceup is occuring and the system is shutting down the blower.

    Also while counting the flashing led I noticed that the status light was steady on. According to the manual this is a "normal fualt detected". Anyone know what this means?

Similar Threads

  1. Getting heater fan to start
    By tabnab in forum HVAC Heating & Cooling
    Replies: 8
    Last Post: 12-23-2008, 09:13 PM
  2. Pump start up
    By PHILIPHD in forum Pumps and Tanks Well Forum & Blog
    Replies: 3
    Last Post: 05-12-2008, 12:13 PM
  3. Shims or start over?
    By nursedoe in forum Shower & bathtub Forum & Blog
    Replies: 11
    Last Post: 10-01-2007, 10:59 AM
  4. delayed start
    By jsmith6752 in forum Pumps and Tanks Well Forum & Blog
    Replies: 2
    Last Post: 07-27-2007, 08:19 AM
  5. where to start?
    By reve4asu in forum Remodel Forum & Blog
    Replies: 5
    Last Post: 09-20-2005, 03:01 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •