I have a carrier furnace and a error led code is one long then an immediate short folliowed by another short before the long

Lucky for Light Emitting Diodes huh? (led)

I'm looking at a legend, on a Carrier furnace door, right now.

One long followed by two short is the "twenty one" code.

Here's what the door sticker says;

"EACH OF THE FOLLOWING CODES IS A TWO DIGIT NUMBER WITH THE FIRST DIGIT DETERMINED BY THE NUMBER OF SHORT FLASHES AND THE SECOND DIGIT DETERMINED BY THE NUMBER OF LONG FLASHES."

Look on your legend, inside the door of the furnace, to find the code diagnostic recommendation.

Make sure to read the codes several times and see the code from the beginning so you make sure the code starts with that digit.

Knowing this furnace means; the code diagnostic recommendation is just that, a suggestion. It will not tell a trained tech what to fix, only a starting point and tell-tale signs.

Code 21 is the gas valve lockout, and will not reset. May be a gas valve, relay or control board (most likely). Call someone.

It's complex for a trained person too, so if you're not familiar, this isn't something to make a mistake on.

Luck to you. Let me know how you get on.
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