I have a Carrier HK06WC069 that is failing to start its heat cycle, the draft inducer spins, then I get a blink code 23, Pressure Switch Stuck Open.
I can pinch the pressure switch’s rubber hose a few times and hear the switch make and break contact as inducer vacuum is drawn and blocked, then the furnace ignites and runs normally until the next shutoff signal from the thermostat. I then have to do the pinch procedure to manually start the ignition again.
No airway blockages on either side of the inducer, rubber hose also clean and in good shape.
Yup, replace the switch.
Sometimes a couple of firm smacks with the back of a screwdriver is enough to get it working again (but you’d be on borrowed time). Even just using your mouth to lightly blow/suck on the tube will flex the diaphragm enough to get it working again.
Also, make sure the small hoses going from the sensor to the furnace are clear. I know you said there aren’t any blockages, but still make sure those tubes aren’t full of water or something.
You can try shorting the contacts to see if that will get you up and running. If you do it when the inducer fires up (and keep them shorted), it’ll run. However, many furnaces will make sure the contacts are open before turning on the inducer. There’s likely a blink code for something like ‘pressure switch closed too early’ or something like that.