I have a high efficiency carrier furnace. When I came home yesterday I noticed that my house was a lot colder then it should be. The fan was blowing but no hot air. I checked the furnace and the LED red light was flashing - 3 quick then 1 long. On the back panel it said this indicated one of a few problems
1. Pressure draft safeguard
2. Auxilary-limit (when used)
3. or block vent shut off (when used)
4. switch did not close or reopen.

I checked outside to see if any leafs were blocking the intake and it seemed clear. Can anyone help with this as I would hate to pay for a service call when it could be something simple and easy enough that I fix.

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Originally Posted by shortensweet

I have a high efficiency carrier furnace. When I came home yesterday I noticed that my house was alot colder then it should be. The fan was blowing but no hot air. I checked the furnace and the LED red light was flashing - 3 quick then 1 long. On the back panel it said this indicated one of a few problems
1. Pressure draft safeguard
2. Auxilary-limit (when used)
3. or block vent shut off (when used)
4. switch did not close or reopen.

I checked outside to see if any leafs were blocking the intake and it seemed clear. Can anyone help with this as I would hate to pay for a service call when it could be something simple and easy enough that I fix.

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There is a reset switch up at the pressure draft safeguard, try to reset it, if you hear a click that was the problem.

Also I would look for all of the safety switches and make sure all are intact and do not need to be reset,

One other suggestion, I would try this one first. Unplug your furnace, turn the thermostat to the off position, and wiat for about five minutes. Now make sure doors are all in place, plug the furnace back in and turn the thermostat to the heat position and make sure the temp is set higher that the actual temp.

Here is another check, take the doors off, use a piece of tape over the door switch to make sure it is held in place. Turn the termostat to the off position, then read the instructions about a test terminal, I think it says jumper from the test terminal to the common terminal on the low voltage portion of the circuit board, hold this for just a second, the furnace will then go through each phase of the cycle except turning on the fire.

Very good

Thanks! It ended up being the pressure switch!

I have a carrier heat and air unit, the led is flashing (1) quick flash, (3) long flashes. It has a switch on the wall, if i flip the switch the heat will come on for one cycle, i can't find any reset switches. Anyone have suggestions
Thank you

You flashes you are seeing could be 1 and 3 or 3 and 1. It is two different codes. And you should have a paper on the front of your furnace that tells you what each code means. Code 31 has to do with the venting system or the limit switches.

One of the things that you can do is to find the pressure switch, it is in the uper part of the furnace and will have two terminal wires connected to it, between these terminals in a smally reset button sticking up about 1/8 of an inch. Press this switch, if you hear a click that means that you have reset the switch and the unit may start. There is another of these switches just above the burners about midway in the furnace, try to reset it the same way.

If this does not help try this. There is a limit switch up above the burners, about twelve inches, it has two wires connected to spade clips. Short across these two post and see if the unit starts.

There is one unit that will give you this code if the circuit board is bad. This board has a black plastic case around it. Good luck.

My furnace has a blinking red light pilot lights but blower nor heat turns on... blinking is not in any certain sequence.

(1) short blink, (1) long blink, (3) short blinks... What does this mean?