I have a 2004 model Ruud Achiever 90 plus downflow furnace in my attic hooked up to a heat pump unit outside. For the last two days the blower fan has run continuously, regardless of whether the thermostat is on heat, cool, or off.
Type of HVAC: Heater & Furnace
All work to be done by licensed professional. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED, I come and go. This is step ONE.
Hello, Welcome to Just Answer, I will stay with you until we get this resolved, there are time limits.
So far it appears the fan relay, often part of the electronics control card has burnt contacts and is keeping the fan on all the time
is there anyway to test or verify this prior to replacing?
If you can find the control card inside the furnace, look for one or two black plastic boxes soldered onto the card, 1/2"cube more or less... tap on them with the hard plastic handle of a small screw driver... if the fan stops, we know the relay contacts were burnt.
Sometimes a unit will work a long time after that... if not you have to replace the control card.
if so, should it be replaced or would the "tap" fix it
you just answered that
can i go try this and come back to you in a few minutes?
Yes, tap first... and just to be sure look on the wiring diagram glued to the inside cover of the furnace access panel for a 'fan relay' shown separate from the control card... I am not expecting there is one. But lets check
ok be right back
there will be a 'fan control' however... thats not the fan relay we are looking for.
Take your time, be sure, there is no rush here.
I do come and go however... if you miss me just post a full comment so I can respond to it when I can.
tried tapping on the plastic boxes and nothing changed. looking on the panel i see the main circuit diagram and then a smaller one to the side. the one on the side has an "FR" which the component code says is a fan relay
this relay is inline with the hcr heat/cool relay and the ibm indoor blower motor
That would be an external fan relay.. see if you can follow the wires to it and tell me what you find
Most of those are about two inches long, an inch tall and maybe an inch wide, with 4 or 5 wires attached... they sell for $10 dollars or so.
Made of black plastic
they can be demounted with one screw on a tab as the back, then one screw removed from the back of the case to reveal the operating coil and the contacts.
ok looking but nothing seen like that yet
the only i see is on the main circuit board 5 small square black plastic boxes labeled K1 thru K5. the other circuit board is a fossil fuel control board that has a large square black plastic box in the middle and there are wires on three side of the board. one says indoor unit, one says outdoor heat pump, the other says plenum sensor. there are wires leading to a small semi-cylindrical black plastic item that penetrates the fan housing. there are two separate metal cylinders (resembling capacitors) approx 1.5" diameter by 2" long (one set of wires running to and from the motor. the other cylinder is oval shaped with multiple blade connectors. Nothing else visible
ya that's the unit except mine is upside down from that photo. the circuit board looks very similar to that one.
The fan relay is *probably on the card but i can't be sure yet. especially given what you reported on the side diagram earlier
".......i see the main circuit diagram and then a smaller one to the side. the one on the side has an "FR" which the component code says is a fan relay
this relay is inline with the hcr heat/cool relay and the ibm indoor blower motor. "
i found nothing on the circuit diagram saying fan relay other than on the secondary circuit board
Im looking to locate that 'FR' item... you found on the diagram earlier
it shows wiring, if you can locate any of those wires shown you can follow them back to the FR item
the diagram doesn't tell me what color the wires are so i'm kinda lost...i'll keep looking
All you need is to find one of the terminals involved, then find that wire, regardless of color and follow it.
Meantime if you have the full model number of the furnace, its on a tag inside I will try to find a manual on it.
I'll try but unable at this point to identify these components. I'll get the model number and send it to you.
could not identify a fan relay. stopped by the appliance parts store and he said it probably had an integrated fan relay on the circuit board. He also said my problem could be a thermal limiting switch that has malfunctioned and the fan defaults to continuous operation. Your thoughts?
Hello again. odds are in the 90% range the fan relay IS on the terminal board. I did not want to guess since Ive not been able to get the manual on that furnace.
One of the wires from the fan motor however will go directly to the fan relay...a fast and bullet proof way to find it if you look at the wiring diagram glued to the service panel on the furnace... they are all marked. There is a legend next to the wiring diagram.. an item marked FR on the wiring diagram will be listed as 'Fan Relay' in the legend.
It could also be the 'fan limit switch' that turns the fan on in heat mode only in some models.
Since I have not been able to find a diagram on that unit, I will opt out, so that another professional here might be able to find that for you.
Please do not click the accept button, leave your funds on account for whomever picks you question up, hopefully in a matter of minutes.
If you could give me model number of that furnace I can pull diagram. Russ