When your heater acts up: quick fixes that saved my winter

Pressure switch codes can be a real pain, but I wouldn’t write them off as just “general direction” pointers. Sometimes they’re dead-on, and ignoring them can make things worse or even dangerous. You mentioned:

Those codes are helpful, but yeah, sometimes they’re just pointing you in the general direction. I wouldn’t trust ‘em blindly, especially when it comes to gas stuff.

I get where you’re coming from - codes don’t always tell the whole story, especially with older units or if there’s more than one issue at play. But in my experience, treating those codes as a checklist rather than a vague hint saves a lot of time and headaches. For example, with a “pressure switch stuck open” code, I always:

1. Kill the power to the unit (safety first).
2. Check the pressure switch tubing for cracks or blockages.
3. Inspect the venting and intake for obstructions (like your squirrel nest).
4. Test the switch itself with a multimeter.
5. Only then do I start looking at the board or wiring.

Skipping steps or assuming it’s just a vent issue can mean missing a failing switch or a wiring short, which could come back to bite you later - sometimes literally, if you’re dealing with gas leaks or carbon monoxide.

Had a call last month where the code said “pressure switch stuck closed.” Turned out to be a faulty board sending voltage when it shouldn’t. If I’d stopped at the vent, I’d have missed it and the customer would’ve been right back where they started.

Long story short: codes aren’t gospel, but they’re not just noise either. Use them as a roadmap, but don’t skip the basics. And yeah, always double-check anything gas-related - no shortcuts there.

I get what you mean about not skipping steps. I’ve seen guys jump straight to replacing the pressure switch just because of a code, but like you said, sometimes it’s just a blocked vent or even a loose hose.

“Use them as a roadmap, but don’t skip the basics.”

Had a similar thing happen last winter - furnace kept shutting off, code pointed to the pressure switch. I almost swapped it out, but something felt off. Turned out the drain hose was half clogged with gunk. Cleared that and it fired right up. Learned to double-check the simple stuff before grabbing new parts... saves time and money.

- Good catch on the drain hose - those little blockages can mimic way bigger issues.
- Always worth checking hoses, vents, and filters before blaming the switch or board.
- Seen a lot of folks swap out parts they didn’t need... quick inspection saves a headache.
- Honestly, sometimes it’s just a $2 fix instead of a $200 one.

- Totally agree - I've learned the hard way that it's not always the expensive part that's the problem.
- Had a tech try to sell me a new control board once, but all it needed was a good clean-out of the vent.
- I get being cautious though... sometimes you just want it fixed fast, but a little patience saves big bucks.
- Respect for doing the legwork instead of just throwing money at it. Small fixes add up to big savings over time.