York Diamond 80 Furnace: blows cold air after brief power interruption yesterday. LED blinks 4 times, indicating limit switch stuck open; checked with ohm meter: it is closed. Suggestions will be appreciated!
Actually, that was the problem. There's a manual reset switch for the incoming air - that's virtually impossible to reach in order to reset! When I loosened the side screws so I could jam my arm into the volume where the blower and the auxiliary temperature limit switch is, I managed to twist the flag (that the switch is attached to) around and push the switch. I couldn't tell if it had been tripped, but when I put everything back together, the furnace started up normally. No obvious reason why this limit switch was tripped by a 30 second power outage . . . Thanks!Actually, that was the problem. There's a manual reset switch for the incoming air - that's virtually impossible to reach in order to reset! When I loosened the side screws so I could jam my arm into the volume where the blower and the auxiliary temperature limit switch is, I managed to twist the flag (that the switch is attached to) around and push the switch. I couldn't tell if it had been tripped, but when I put everything back together, the furnace started up normally. No obvious reason why this limit switch was tripped by a 30 second power outage . . . Thanks!
After sleeping on it, I realize that the power went off as the furnace was developing maximum heat. Since it is a DOWNDRAFT installation, the air that had just been heated was below the heat exchanger; with the blower off, this heated air would rise by convection back through the heat exchanger - heating up even more - and rise through the blower. The limit switch at the blower intake would sense the rising hot air and trip. This means limit switch was doing what it should do, but for a very abnormal condition whose cause is outside our control. And that it was NOT an electronic power surge issue . . .
After sleeping on it, I realize that the power went off as the furnace was developing maximum heat. Since it is a DOWNDRAFT installation, the air that had just been heated was below the heat exchanger; with the blower off, this heated air would rise by convection back through the heat exchanger - heating up even more - and rise through the blower. The limit switch at the blower intake would sense the rising hot air and trip. This means limit switch was doing what it should do, but for a very abnormal condition whose cause is outside our control. And that it was NOT an electronic power surge issue . . .
Had a similar problem yesterday after a power outage. On my unit the small, round switch sits just on top of the blower motor and is easily accesible. The reset is right in between the two connection tabs.Had a similar problem yesterday after a power outage. On my unit the small, round switch sits just on top of the blower motor and is easily accesible. The reset is right in between the two connection tabs.
You can't post conmments that contain an email address.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
? 13:25
https://www.youtube.com/watch?v=rAtcvPqUsBA
Dec 18, 2012 - Uploaded by JRESHOW .
cause this fault. 2 RED FLASHES: This indicates that thenormally open pressure ... The furnace will lock out for one hour and then restart. 7 RED FLASHES: This fault code indicates that the flame could not be established. This no-light ... problem. Bothheating and cooling operations will be affected. Check
Each step in the process must be satisfied in order to go to the next one. Yes, make sure the "Hot Surface Igniter" is good. Is the venter motor reaching full speed to close the air switch? Did you check the end of the vent pipe that nothing is obstructing it - like a bird.
TRI-COLOR (DSI LED) DIAGNOSTIC TABLE
No. of Red BLINKS
1 Flame sensed when no flame should be present
Verify the gas valve is operating and shutting down properly. Flame in burner assemble should extinguish promptly at the end of the cycle. Check orifices and gas pressure.
3 BLINKS 1st-stage pressure switch stuck open/inducer error
Check pressure switch function and tubing. Verify inducer is turning on the pulling sufficient vacuum to engage switch.
4 BLINKS Open limit switch Verify continuity through rollout switch circuit.
5 BLINKS Open rollout/open fuse detect Verify continuity through rollout switch circuit, check fuse.
6 BLINKS 1st-stage pressure switch cycle lockout If the first stage pressure switch cycles 5 times (open, closed) during one call for heat from the thermostat the control will lockout.Check pressure switch for fluttering, inconsistent closure or poor vacuum pressure.
7 BLINKS External lockout (retries exceeded) Failure to sense flame is often caused by carbon deposits on the
flame sensor, a disconnected or shorted flame sensor lead or a
poorly grounded furnace. Carbon deposits can be cleaned with
emery cloth. Verify sensor is not contacting the burner and is locatedin a good position to sense flame. Check sensor lead for shortingand verify furnace is grounded properly.
8 BLINKS External lockout (ignition recycles
exceeded where flame is established and then lost)Check items for exceeded retries listed above and verify valve is not dropping out allowing flame to be established and then lost.
9 BLINKS Grounding or Reversed polarity Verify the control and furnace are properly grounded. Check and reverse polarity (primary) if incorrect.
10 BLINKS Module gas valve contacts energized
with no call for heat Verify valve is not receiving voltage from a short. If a valve wiring is correct and condition persists, replace module.
11 BLINKS Limit switch open - possible blower
failure overheating limit Possible blower failure, restricted air flow through appliance or duct work. Verify continuity through limit switch circuit and correct overheating cause.
12 BLINKS Module Ignitor contact failure Fault code indicates the module ignitor contacts are not functioning
properly. Replace module.Solid Module - internal fault condition Module contacts for gas valve not operating or processor fault.
Reset control. if condition persists replace module.
3 double 2nd-stage Pressure Switch Stuck Open/Inducer Error
Check pressure switch function and tubing. Verify inducer.
4 blinks indicates a failure at the high limit switch. This switch is usually located on the heat exchanger face plate and has two wires going to it. Usually it fails because the furnace has over heated. The most common reasons are a plugged filter or coil that is limiting the airflow over the heat exchanger. Turn off the power to the furnace, replace the filter, clean any coils in the plenum and verify that all the vents in the home are open. Then turn the power back on and see if it is fixed. :)
If the above solution does not fix the problem, the limit switch itself may be bad from excessive heat. Replace it with a new one. Good Luck!
Hi,
One of the limit switch in the furnace is tripped or went bad....
Try to find all of the reset switches and push the little red button on the top to reset them...
If that don't work you will need to take an electric meter and test each switch to see which one is bad...
Actually, that was the problem. There's a manual reset switch for the incoming air - that's virtually impossible to reach in order to reset! When I loosened the side screws so I could jam my arm into the volume where the blower and the auxiliary temperature limit switch is, I managed to twist the flag (that the switch is attached to) around and push the switch. I couldn't tell if it had been tripped, but when I put everything back together, the furnace started up normally. No obvious reason why this limit switch was tripped by a 30 second power outage . . . Thanks!
After sleeping on it, I realize that the power went off as the furnace was developing maximum heat. Since it is a DOWNDRAFT installation, the air that had just been heated was below the heat exchanger; with the blower off, this heated air would rise by convection back through the heat exchanger - heating up even more - and rise through the blower. The limit switch at the blower intake would sense the rising hot air and trip. This means limit switch was doing what it should do, but for a very abnormal condition whose cause is outside our control. And that it was NOT an electronic power surge issue . . .
Had a similar problem yesterday after a power outage. On my unit the small, round switch sits just on top of the blower motor and is easily accesible. The reset is right in between the two connection tabs.
×