Carrier Furnace, LED flashing 3-2

[Tim]

Furnace at the office is a Carrier 8000TS, probably 12 years old. The LED is flashing 3-2 (3 quick flashes followed by 2 longer) which could be several things, including faulty pressure switch.

I pulled the hoses off and they were clear. Stuck a paper clip in the ports and rooted around to make sure they were clear. The furnace kicked on for a few minutes after that, then went back to flashing 3-2.

Should I replace the pressure switch myself or call the man? I don't mind a DIY approach, but if I'm likely to go chasing one thing after another, I'd rather pay the man.

 

[Ferrisfan]

Pay the man. DIY at the office just screams liability to me.

 

[Timfoilhat]

My experience with pressure switches says you can remove it and try to blow on the tube to see if you can hear it click open and shut. I've also been able to identify one that had a torn diaphragm in it.
That's about the limit of my experience, and once I change it or eliminate it as a problem if it still doesn't work it's time to call the man.