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QUESTION: Trying to troubleshoot a blower problem on a American Standard Freedom 80 Comfort-R series Furnace/AC system (Furnace AUD080R9V3K0)

The Thermostats calls AC and Heat fine, but when trying to turn on the fan from the thermostat, or jump the green and red wires on the control board, the blower comes on (Sometimes pulses 3 or 4 times), then spins down.  Loops like this continuously.  The GREEN LED will come on when the fan spins down, and sometimes blinks 6 or 7 times before trying to spin up again.  The RED LED blinks slow as normal, and Fast when heat is called.  

Is there a chart somewhere for the green LED?  Is there something I can test on the Connection from the control board to the blower that will identify if it is the control board or something in the blower circuitry?  Thanks.

ANSWER: KnC,

I do not know what the green LED or blinking 6 times pulses 3 or 4 times mean.Each Company hasve different codes. Usually there is a status/code decal somewhere on a inside panel, if not try goggle or yahoo your model number and you may find one. You say your heat heat/cool works fine, it's only when you put the fan to the ON position that you have trouble. What happens when nothing is calling ( system OFF ) and you put your fan to the ON position, do you have problems?. This is what I would do ,I would remove the t-stat from the subbase and remove the wire on the R terminal and remove the G wire from the t-stat then jumper together if your fan runs OK then you have problems with the t-stat. If you still have the problem with the blower fan shutting down, you would need to troubleshoot via a meter and know what your doing. Find the fan relay coil and see if your loosing 24 volt ac at the coil two points. To me you have a control problem, your loosing power to the fan relay  when placing t-stat fan switch  to ON. Also you do not jump the green and red wire at the control board as you state. You jumper the R wire and G wire  terminal at the control board.I do not for a fact that your system wiring uses the Red for R and Green for G from here.It's possible you have a control board issue if you jumper R to G at the board and the fan starts then drops out.Again you would need to verify with a meter at the fan relay coil two points.You should always have 24 volt ac at the fan coil as long as the the R and G is jumper either at the stat or board.

---------- FOLLOW-UP ----------

QUESTION: Thank you for responding.


The control board in the Blower compartment has 5 LEDs:

1.) RED LED which I have found a diagnostic chart for the FURNACE CONTROL. This LED blinks normal.  "Slow blink when in ready state, and faster blink when calling for heat" per the chart that is inside the blower compartment door.

2.) YELLOW LED labeled DS3.  As far as I can tell this comes on when it calls for just FAN.  No chart available, so this is my assumption ,but that is the consistent behavior.

3.) YELLOW LED labeled DS4.  This comes on when it calls for AC.  (Note that DS3 is on as well when this LED is lit.)  No chart available, so this is my assumption ,but that is the consistent behavior.

4.) YELLOW LED labeled DS5.  This comes on when it calls for HEAT.  (Note that DS3 & DS4 come on as well when this LED is lit.)  No chart available, so this is my assumption ,but that is the consistent behavior.  

*** 5.) GREEN LED that is on the board side of the surface mount fuse that is the HOT WIRE FOR CIRC going to the blower.  No chart available, and the only association I can make is that it comes on only when the fan cycles off... after the blower spinning up, and something shutting it down, this LED will blink the 6 times before the blower attempts to ramp back up again. I do not hear or feel any of the 5 relays on the control board kicking when this LED changes state.

All LEDs are off when system is off.  The green LED and blower behave as stated whether it is in "FAN ONLY", "COOL", or "HEAT" modes.  blower will initially make a pulsing motion, when spinning up.  (The sound made me think the bearings where bad, or the the something was bent.  But when power is off, the motor spins free without any noise or noticable wobble.  It seems to be making the pulsing motion and noise because of power being applied to the motor inconsistently.  Which leads me to another interesting question.  Are the 16 white wires going to the motor signal lines, or are they applying incremental voltage levels to the motor?  (See note at bottom.)

I have jumped the "G" and "R" wires at the Thermostat connector on the control board.  (It was easier than climbing up and down an attic ladder, as I am not that young anymore ;) If the DS3, DS4, DS5 LEDs are behaving as I suspect, and the Condensor, Furnace, and Fan calls work, my guess is the Thermostat is fine.

The transformer the board is producing 24 volts, because the board traces are on the back side, I have not really gone that far in diagnosing because I am certain the GREEN LED Behavior is indicating something, I just can not find a chart online.


CONCLUDING NOTE:  I have had 2 AC guys look at this unit, and one wants me to get a chart for the green LED (confirming my assumption?), and the other wants to replace the blower first, and then "if that doesn't fix the problem... replace the logic board.".  I am not an HVAC technician, I am an old school Network engineer, computer tech, and electronic hobbiest (35+ years).  It has been a few years since I have had to troubleshoot at a PCB level, but I am not afraid of electricity, and have an understanding how circuits work.  I have no problem unsoldering a relay, or even an IC to replace it, if I know that is the problem.  The "if that doesn't work scenario" does not sit right with me.  I want to know what the problem is before I pay someone to replace something... If I can do it myself even better.  ;)  The blasted warranty ran out last year, so getting American Standard to even provide documentation is like pulling teeth, much less get them to cooperate with an un-licensed dealer.

I hope this helps.  Thanks again!

ANSWER: KnC,

From your initial post you state that your system works fine when in heat or cool mode "The Thermostats calls AC and Heat fine "  If you meant to say the A/C comes on OK except the blower motor does not or the heat works OK but the blower motor does not come on then there is a problem with your low voltage circuit or faulty motor , or a bad run capacitor  , or the motor is bound up or the motor mounts are loose and the blower is shaking when running.The Tech who want to replace the blower first and if that does not solve the problem want to change the board to me does not have much experience troubleshooting a system. If your motor is shutting down either the fan relay 24 volt ac coil is dropping out or the 220 volt ( if your fan section is a 220 volt section ) is dropping out, or your motor is overheating and the internal overload of the motor is opening and shutting off the power to the motor. Google HVAC parts, there are many web based companies that sell parts .I'm sure you can find your board for a very reasonable price. Also try replacing the motor run capacitor ( a minimal cost item ) $20.00 or replace the motor and get a new capacitor.Buy from grainger.com a nationwide company, needing only a account set up. Guessing you can buy a a motor and capacitor and board for $200.00 far less than a HVAC company would charge you. The motor only needs to be the correct voltage, RPM, and amperage rating and HP rating . Buy a reversible rotation motor so there is no doubt about getting the correct rotation.

---------- FOLLOW-UP ----------

QUESTION: That's good info.  I plan to break out the multimeter and nose around.  My initial thought was a relay, or some type of sensing circuit.  I looked at the circuit board, and did not see any blown capacitors, or burnt resistors, or LEDs.  I have been wanting to apply power to the motor without all the back end logic to rule out the blower, but all those wires make me believe that there is addition logic controls in the motor. (I haven't pulled it or seen what the connections look like.)...   

The green LED just has me curious, and it makes logical sense that they wouldn't put the LED on the board if it wasn't indicating something?  My hope is that I can get someone who has that level of knowledge of the American Standard LEDs before I spend a lot of time trying to learn something I am not going to pursue outside my own furnace. ;)

I appreciate all your time.

Answer
KnC,

I researched you furnace, I assumed you had a single speed blower motor as your is a 80% furnace but it says you have a variable speed blower motor.So the above info about replacing your motor at the cost I gave you do not apply. I would hire a Company if the original installing company can't help you who installed it and ask for a tech. who is factory  trained in variable speed furnaces American Standard brand.Try downloading the install guide ,troubleshooting guide via internet.Your system is fairly new so info should be relatively available.I do not sell American Standard and am not familiar with the sequence of operation of that model. You can try another expert also. My fault, I was under the impression you had a standard single speed motor. Variable speeds are nice but cost more to repair than standard multi speed motors and are more complicated.

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40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.

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Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

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Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

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