ResMed CPAP Humidifier Not Working: HumidAir Troubleshooting

Quick Answer

The ResMed HumidAir humidifier on AirSense 10 and 11 devices stops working most often because the gold electrical contact pins between the water chamber and the device base become corroded or coated with mineral deposits from non-distilled water. Cleaning these pins with isopropyl alcohol on a cotton swab resolves the issue in roughly half of cases.

Most of the time when I get called about this, the person woke up with a bone-dry throat and the water in the chamber is at exactly the same level as the night before. Not a drop less. Dirty contact pins fix it in about half the cases I see. The rest? Chamber wasn't clicked in all the way, or someone's been filling it with tap water for two years and the heating plate is basically coated in concrete.

ResmedCpapSeverity: moderate75% DIY Success

Time to Fix

5–20 min

Difficulty

beginner

Parts Cost

$6 – $45

Tools Needed

Isopropyl alcohol 70% or higher, Cotton swabs

What Does the HUMID-FAULT Code Mean?

The AirSense 10 and 11 are picky about that water chamber in a way that surprises most people. It's not just plug and play. The machine actually reads resistance through those contact pins to verify the tub is there and working. If it doesn't get the right signal, it just doesn't send power. Saw this exact problem three times last week. Before you call ResMed or buy anything new, check the obvious stuff first.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Gold contact pins corroded or dirty40%

Water chamber not fully seated24%

Mineral buildup from tap water on contacts14%

Heating plate inside chamber failed12%

Water chamber cracked or warped from dishwasher use10%

Symptoms You May Notice

You wake up with a throat like sandpaper and your nose feels like you slept in a desert.
The water in the chamber is exactly the same level as when you went to bed. Not a drop less.
Tubing and mask feel bone dry. No warmth, no moisture, nothing at all.
The humidity icon is missing from the home screen, or there's a warning symbol where it should be.
Running therapy with the tub in feels exactly the same as running it without the tub.

Can you reset a Resmed cpap to clear the HUMID-FAULT code?

Unplug the power brick from both the wall and the back of your device. Both ends, not just the wall. Wait a full 60 seconds, not 10, not 30. Then plug back in at the device first, then the wall. The machine re-initializes and rescans for the humidifier assembly. After it boots up, go into My Options and confirm your humidity level didn't reset to zero. This power cycle clears the temp sensor cache and fixes weird reading issues more often than you'd think.

Tools Required for Diagnosis

Isopropyl alcohol 70% or higherCotton swabsDistilled waterWhite vinegar (for descaling mineral deposits)Soft toothbrush (for scrubbing the heating plate)Soft dry cloth

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
ResMed HumidAir Water ChamberN/A · $25–$45	N/A	$25 – $45
ResMed HumidAir Water Chamber Seal GasketN/A · $6–$15	N/A	$6 – $15

Frequently Asked Questions

Can I use tap water in my ResMed humidifier?

Tap water won't break the machine instantly, but the calcium and lime buildup acts like an insulator. It creates a crust over the heating element that forces it to work harder and eventually burn out. In my shop, I can always tell who uses tap water by the white ring around the tub. If you've got no choice, do a vinegar soak weekly to keep the metal plate exposed and efficient, but switch to distilled as soon as you can. Distilled water is like $1 a gallon. That chamber is $40.

Can I run my CPAP without the humidifier?

You definitely can, but I wouldn't recommend it for more than a night or two. The AirSense series is designed to detect the tub. If you leave it out, you need the Side Cover accessory to plug that slot, otherwise air just blows out the side instead of through the hose. Without humidity, most people wake up with cotton mouth or sinus pressure. If your heater's broken, you can actually still use the tub as a passive humidifier by filling it with room-temp water. Zero heat, but a little moisture is better than none.

How do I clean the HumidAir water chamber?

Forget the dishwasher, even if the manual says it's safe. The high heat cycles in modern dishwashers can warp the plastic housing just enough that the electrical contacts won't line up anymore. Stick to warm water and mild, scent-free soap. If you see white spots, use a 50/50 mix of water and white vinegar, let it sit for twenty minutes, and those minerals wipe right off without you having to scrub and scratch the plate.

The humidifier worked last night but not tonight. What happened?

That's almost always the contacts. When they're borderline dirty, they'll work when they happen to make good contact and fail when they don't. It's basically like a loose wire in your car. Works on smooth roads, cuts out on bumps. Pull the tub, clean those gold pads with isopropyl alcohol, push it back in firmly until it clicks, and try again. If it works a few nights and then fails again, the contact pads on the tub itself might be worn down enough that it needs replacing. A new chamber is $30 to $50 and usually fixes it for good.

How do I know if it's the water chamber or the main machine that's broken?

Here's the easy test. Clean the contact pins and confirm the settings are right. If the heating plate still doesn't warm up after 15 minutes of therapy, try borrowing a friend's HumidAir chamber or grab a cheap replacement tub and swap it in. If the borrowed tub works, your chamber's dead. If it still doesn't heat up with a known-good tub, the problem's in the base unit itself, which usually means a repair bill or a full device replacement. Don't buy a new tub until you've ruled out the base, because a $40 part won't fix a $900 problem.

Related Resmed Cpap Error Codes

Code: HUBResMed CPAP Error Codes: Complete AirSense 10 and 11 Fault Guide Code: HUMID-ERRORResMed CPAP Humidifier Fault Code: HEAT-ERRORResMed CPAP Heating System Error Code: LEAK-WATERResMed CPAP Leaking Water: Causes and Fixes

Models Known to Experience HUMID-FAULT Errors

This repair applies to most Resmed cpaps with this error code. Common model numbers include:

AirSense 10 AutoSet, AirSense 10 CPAP, AirSense 10 Elite, AirSense 10 For Her, AirSense 11 AutoSet, AirCurve 10 VAuto, AirCurve 10 ST

Written by

Sarah Kim

Smart Home & Specialty Appliance Tech · 12 years experience

Last verified for technical accuracy on March 15, 2026