HVAC Maintenance Plans in Vancouver, WA
Two visits a year. Every number written down.
No calendar upsells. No mystery invoices. No "priority service" that isn't. Just a system that gets measured, not guessed at — twice a year, by the same guy who'll pick up the phone when it breaks.
Most maintenance plans are a bad deal. Here's why ours isn't.
Independent consumer watchdogs have been saying it for years: HVAC maintenance contracts are usually bad buys. They're mostly right. Three reasons come up every single time — so here's what we did about each one.
① "Priority" that isn't
The problem: Every shop promises you'll jump the line. Then July hits and you wait two weeks like everybody else.
What we do: We tell you exactly where you land. Pro members are first — ahead of everyone. Baseline members go ahead of anyone without a plan. That's the whole promise, and it's one we can keep on the hottest day of the year.
② Two upsell visits a year
The problem: A lot of shops treat a maintenance visit as a chance to find something to sell you. Twice a year, like clockwork, something's "starting to go."
What we do: We take measurements and we write them down — amps, pressures, static pressure, temperature split, combustion. If the numbers are fine, we tell you the numbers are fine and we leave. You get the report either way.
③ The cleaning that isn't included
The problem: The single most common exclusion in maintenance plans is the coil cleaning — the thing your system actually needs.
What we do: On Pro, the deep work is included. Not on a calendar — when the readings say your system needs it. We published the thresholds, and they come off your equipment's nameplate, not out of our heads. If your numbers cross one, the work happens and there's no invoice. If they don't, we show you the numbers that say why.
Which system do you have?
Central System
Gas furnace + AC, or a heat pump with an air handler. Ductwork, vents in the ceiling or floor.
From $29/moDuctless Mini-Split
Wall-mounted or ceiling cassette units, one outdoor unit (or a few).
From $19.90/moNot sure? Pick either — we'll sort it out before anything gets charged.
Furnace + AC · Heat Pump + Air Handler
Two visits a year: one in spring for cooling, one in fall for heat. Same technician, same instruments, same report both times.
When we come out. We schedule both visits — one ahead of cooling season, one ahead of heat. If we haven't got you on the calendar by the end of your plan year, we'll reach out and book it before it lapses. Visits don't roll over into the next year.
One thing we'll ask: we don't book deep restoration work in July or August. That's when systems fail, and members who need a repair come first. Every other month is open.
| What you get | Baseline$29/mo · or $319/yr | Most popularPro$429 for the year |
|---|---|---|
| 2 seasonal visits | ✓ | ✓ |
| Full measurements — fan amps, compressor amps, refrigerant pressures, superheat/subcool, temperature split, capacitor | ✓ | ✓ |
| Static pressure test | ✓ | ✓ |
| Combustion analysis — CO, O₂, draft | ✓ | ✓ |
| Condenser rinse | ✓ | ✓ |
| Evaporator dry clean (where we can reach it) | ✓ | ✓ |
| Written report, every visit | ✓ | ✓ |
| Deep restoration work — when your readings cross the published thresholds | — | Included |
| Repairs (labor only) | 10% off | 20% off |
| Diagnostics ($99) | 1 free per year | Always free |
| Nights & weekends | standard rate | No surcharge |
| Filters | — | Included |
| Installation discount, earned by tenure | — | $100 per full year, up to $1,000 |
| Priority | Ahead of anyone without a plan | First in line |
| Commitment | None — month-to-month | None — one year, paid up front |
Prices shown are before Washington state and local sales tax. · Membership terms →
Why we measure — the actual numbers
Pro includes deep restoration work. Not automatically every year — when your system's readings say it's needed. Here's exactly what "needed" means, so you're not taking our word for it:
- Static pressure at or above your equipment's rated maximum. That number is printed on your air handler or furnace nameplate. On most residential systems it's 0.50 inches of water column — the most your blower is rated to push against, which is a different number from the 0.10 to 0.20 the lab used to rate its efficiency. Yours might be different. We read yours, not an average.
- Cooling temperature split outside the manufacturer's range for the indoor conditions we measured that day.
- Heating temperature rise outside the range printed on your furnace nameplate. Every furnace has one. It's usually a 30-degree window.
- Liquid-line subcooling more than 3°F off the manufacturer's target. That target is model-specific — it's on the nameplate or in the service facts, and across brands it runs anywhere from 8°F to 19°F. The tolerance isn't ours either: ANSI/ACCA 9 QIvp-2016 sets it at ±3°F. On fixed-orifice systems we use superheat instead, at ±5°F, from the same standard. This test needs an outdoor temperature above 55°F to mean anything, so in deep winter it waits for a warmer day.
- Blower or compressor amp draw at or above the nameplate rating.
Any one of these, and the deep work is included. Your equipment sets the thresholds. We just read them out loud.
First year is usually a yes, because most systems come to us having never been measured. After that it's typically every second or third year.
One ask, not a contract: the deep restoration usually lands in your first year, and it's the most expensive thing we do. We're not going to lock you in for it. We'd just rather you didn't take the first-year work and disappear in month four — and if you do, we'll survive it.
Why one is monthly and the other isn't. Baseline is maintenance — twice a year, every year, so it's priced like a subscription. Pro is a restoration year with maintenance attached. The heavy work lands early, so it's paid for up front. After the year, you pick: another year of Pro, or drop to Baseline monthly. We'll ask you before it renews either way.
Two visits a year. Every number written down. Cancel anytime.
The math on Baseline: two tune-ups at $199 each is $398. One diagnostic is $99. That's $497 if you pay as you go. Baseline is $319 paid annually, or $29 a month — and you don't have to remember to book anything.
The math on Pro: everything in Baseline, plus the deep restoration work when your readings call for it, plus 20% off repair labor, plus unlimited diagnostics, plus $100 toward your next system. $429 for the year, paid once.
It's paid up front because the work happens up front. Most systems come to us having never been properly measured, and the first year is where we fix that. We'd rather charge you for it honestly than lock you into a contract to get it back later.
Wall units · Ceiling cassettes
One visit a year — and that's enough, as long as you rinse your filters every six weeks or so. We'll show you how, and we'll text you a reminder when it's due.
When we come out. On Deep Clean, we schedule your visit ahead of the season you're about to lean on — heating or cooling, depending on when you signed up. On Performance Max, you pick the month: tell us any time and we'll book it. If we haven't heard from you by the end of your plan year, we'll reach out and get it scheduled before it lapses. It doesn't roll over into the next year.
One thing we'll ask: we don't book deep cleans in July or August. That's when systems fail, and members who need a repair come first. Every other month is open.
| What you get | Most popularDeep Clean | Performance Max |
|---|---|---|
| Annual visit — full clean, indoor and out | ✓ | ✓ |
| Blower wheel cleaned under pressure, in place | ✓ | — |
| Blower wheel removed, cleaned off the unit, reinstalled | — | ✓ |
| Outdoor unit — always included | ✓ | ✓ |
| Chemical treatment on the outdoor coil when the readings call for it | — | ✓ |
| Full measurements — temperature split, amps, capacitor, drain | ✓ | ✓ |
| Written report | ✓ | ✓ |
| Filter reminders — every 6 weeks | ✓ | ✓ |
| Repairs (labor only) | 10% off | 20% off |
| Diagnostics ($99) | 1 free per year | Always free |
| Nights & weekends | standard rate | No surcharge |
| Installation discount, earned by tenure | — | $100 per full year, up to $1,000 |
| Priority | Ahead of anyone without a plan | First in line |
| Commitment | None — month-to-month | None — month-to-month |
Deep Clean — wall-mounted units
| Heads | Price |
|---|---|
| 1 | $19.90/mo$228/yrone-off $249 |
| 2 | $27.40/mo$315/yrone-off $343 |
| 3 | $34.90/mo$402/yrone-off $437 |
| 4+ | Let's talk — same math, we'll just run the numbers |
Performance Max — wall-mounted units
| Heads | Price |
|---|---|
| 1 | $25.50/mo$294/yrone-off $319 |
| 2 | $38.70/mo$444/yrone-off $483 |
| 3 | $51.75/mo$595/yrone-off $647 |
| 4+ | Let's talk — same math, we'll just run the numbers |
Ceiling cassettes: one price, not two
| Cassettes | Price |
|---|---|
| 1 | $29.50/mo$342/yrone-off $365 |
| 2 | $46.00/mo$529/yrone-off $575 |
| 3 | $62.80/mo$722/yrone-off $785 |
| 4+ | Let's talk — same math, we'll just run the numbers |
Prices shown are before Washington state and local sales tax. · Membership terms →
Cassettes come apart or they don't come clean. To reach the coil you're pulling the fan out either way — there's no in-place version of this job. So there's one price for a cassette, not two, and it already includes everything Performance Max includes.
It costs more than a wall unit because it is more work: overhead access, a drain pump to deal with, and a full teardown before you touch anything that matters. We'd rather show you that number than bury it as a surcharge.
Cassette customers get the full Performance Max feature set — 20% off repair labor, always-free diagnostics, the installation discount, and first-in-line priority.
Each additional outdoor unit: +$5/mo, +$57/yr, +$62 one-off.
More than one head? Here's the honest math.
Two things happen exactly once, no matter how many heads you have — we show up, and we clean the outdoor unit. Those get charged once.
Every indoor head gets the full job after that. Same pressure, same chemistry, same time. We don't discount the work, because we don't do less of it. A second head takes us the same hour the first one did.
That cuts both ways, and it's worth saying out loud: plenty of shops drop their per-head price on a multi-zone. We don't. If you want the number behind that — one head works out to about $85 an hour of our time, and three heads works out to about $86. Same rate either way. You're not getting a volume discount and you're not paying a volume penalty.
Got three separate single-zone systems instead of one multi-zone? Then you've got three outdoor units, and each one gets cleaned and each one gets charged. What you save is us showing up twice more.
Ducted mini split in your attic? That's not a cleaning job — that's an airflow job, and the difference matters. Here's why →
Every visit. Every number.
The instruments don't come out based on what you pay. Same checks, same report — whether you're on Baseline or Pro.
Spring · Cooling
- Fan motor amp draw
- Compressor amp draw vs. nameplate
- Refrigerant pressures
- Superheat / subcooling
- Temperature split across the coil
- Capacitor tested against its rating
- Contactor inspection
- Static pressure test
- Condenser coil rinse
- Evaporator dry clean (where accessible)
- Drain line flow check
- Filter check / replace
- Thermostat calibration
Fall · Heating
- Combustion analysis — CO, O₂, draft, stack temp
- Manifold gas pressure
- Flame sensor cleaning
- Burner compartment vacuum
- Temperature rise vs. nameplate
- Ignition system check
- Safety controls — limit, rollout, pressure switch
- Blower amp draw
- Static pressure test
- Heat pump: defrost cycle, reversing valve, aux heat
Mini-Split · Annual
- Blower wheel cleaned under pressure
- Indoor coil cleaned
- Drain flushed
- Outdoor unit washed
- Temperature split — room air in, supply air out
- Fan and compressor amps
- Capacitor tested
- Filters washed + we show you how
- Full mode check — cooling, heating, defrost
Every visit ends with a written report. Not a checklist with checkmarks — the actual numbers, so you can compare them to last year.
Four things we do differently — and why
① We wash your condenser from the inside out
Dirt goes into your outdoor coil from the outside. So when a guy hoses it down from the outside, he's pushing that dirt deeper into the coil. The fins look great. The coil is still choking.
To actually clean it, you pull the top off and wash it the way the dirt came in — from the inside out. That's an hour instead of ten minutes. That's why almost nobody does it.
② Pressure does the work. Chemistry finishes it.
The growth on a mini-split blower wheel is a film. You don't spray a film away — you take it off with pressure. Anyone selling you a chemical treatment as the main event is selling you the wrong thing.
What the enzyme cleaner does is break down and carry off the organic residue that water alone leaves behind. That's why the smell doesn't come back in six weeks — not because we sprayed perfume on it, but because the stuff making the smell isn't there anymore.
We're not going to tell you we "treat" your system with anything it doesn't need. Nobody who overpromises there is using a product approved to do it.
③ We don't take your furnace apart for nothing
A lot of shops list "heat exchanger inspection" on their checklist. Doing it properly means pulling the burners — a 45-minute teardown that plenty of them bill for and don't actually do.
We run a combustion analysis first: CO, O₂, draft, stack temperature. Ten minutes, and it tells us whether there's a reason to go in. If there is, we pull the burners, inspect it properly, and you'll see the photos. If there isn't, we're not charging you to take your furnace apart on spec.
④ If your system is choking, we'll show you the number
Sometimes it's the filter. Sometimes it's the ductwork. Sometimes it's the coil.
We measure static pressure on every visit and you get the number either way. We're not going to sell you a coil cleaning when the problem is a collapsed duct.
Nothing buried at the bottom
① Founding member rate
These are launch prices. They're set low on purpose — we'd rather have a year of your readings than a better margin on the first job. If you join now, we hold your rate through 2027.
After that, if it goes up, you get 30 days' notice and you can leave instead. We're not going to move the number on you quietly, and we're not going to pretend these prices last forever either.
② Cancel in about a minute. No conversation.
Fill out the form at heisenbergwa.com/cancel, or just text or email us the word "cancel." One line is enough. No phone tree, no retention script, no "let me transfer you to my supervisor."
We process it within one business day and send written confirmation. If we're late and a charge goes through, we refund it.
Every monthly plan is month-to-month. Prepaid plans — see the refund terms below.
③ It renews on its own. We ask you first.
Your plan renews so nobody has to remember anything. Before it does, you get an email with the date and the amount, plus what your readings looked like that year, so you can decide whether to stay where you are or move up or down a tier.
If the price is going up, we tell you at least 30 days ahead and you can leave instead.
④ The installation discount, explained honestly
Every full year you complete on the top tier earns you $100 off a system installation with us, up to $1,000. It isn't an account and it isn't money — it's a discount we apply at the time of the install, and it's yours as long as your membership is active.
It's tied to you and this address. It doesn't transfer to a new owner, it has no cash value, and it doesn't stack with other promotions. If you leave the plan, you stop earning it and the discount no longer applies.
We're telling you that up front instead of putting it in a footnote.
⑤ What "priority" actually means here
Pro: you're first. Ahead of everyone. Baseline: you're ahead of anyone who doesn't have a plan.
We're not going to promise you same-day in the middle of a 98° week and then have you wait three days. This is a promise we can keep in August.
⑥ What if it comes back before the year is up
Deep Clean. We clean the wheel in place, and that holds for a season if you rinse your filters. We remind you every six weeks. If growth comes back inside the plan year anyway, we'll come out and redo it at half price — we'd rather split it with you than argue about whose fault it was.
Performance Max. We take the wheel out. If growth comes back inside twelve months, that's our method failing, not your filters — we redo it and there's no invoice.
⑦ Our repair warranty. Same for everybody.
One year on our labor for any repair we do. That's not a membership perk — members and non-members get the same year. If we fixed it and it fails again inside twelve months, we come back and there's no invoice.
Parts carry whatever the manufacturer gives them. That's usually a year on a replacement part, and the manufacturer covers the part only — never the labor to put it in. We file the claim for you either way.
One thing worth knowing: manufacturers can ask for proof of maintenance before they honor a warranty claim. The report we leave after every visit is that proof, dated and signed. That's most of why the plan pays for itself when something actually breaks.
⑧ What the plan doesn't cover
The plan buys maintenance. It doesn't buy repairs. Here's the line, drawn clearly:
- Parts and repairs. The member discount applies to labor only — parts, refrigerant, and materials are billed at cost. You still get your diagnostic benefit, and the repair itself is quoted and billed separately.
- Refrigerant. Charging, recovery, and leak repair are repair work, not maintenance.
- Duct cleaning, sealing, and modification. Different job, separately quoted. We'll measure your static pressure and tell you if you need it.
- Equipment we can't safely reach — no attic access, no walkway, blocked crawlspace, live wasp nest. We'll tell you on the spot and reschedule once it's clear.
- Problems from someone else's installation. We'll document them and quote the fix. We won't absorb them.
- Equipment that can't be maintained. If a system is unsafe or too far gone to service, we'll show you the readings and refund the unused portion of your plan.
- Commercial and multifamily. Residential only, one to four units.
- Anything we recommended and you declined. If we wrote it in the report and you chose not to do it, we're not responsible for what it does next.
Unlimited diagnostics on the top tier means diagnostics on your own system during normal business hours, at reasonable frequency. It isn't a subscription to unlimited visits, and we'd rather say so now than argue about it later.
⑨ If you leave partway through
Monthly plans: nothing to refund. You stop being charged. No termination fee, ever.
Paid annually: we refund what's left of the year, minus the work we've already done at our published prices. If we've already been out, that math often comes out at or near zero — because the visit was worth more than the discount you got for prepaying. We'll show you the arithmetic either way.
Central Pro: same math. If we did the deep restoration in March and you leave in May, expect zero — the work was worth more than the plan cost.
That's not a penalty and there's no fee attached to it. It's just what we already did, priced the same way we price it for everybody else.
Frequently Asked Questions
Why is Pro cheaper than the deep cleaning it includes?
Because we don't do the deep work every year. We do it when your system's numbers say it needs it — usually year one, then maybe every third year after that. You're paying for the fact that when it's needed, it's included. Not for a cleaning you didn't need. The thresholds that trigger it are published above, so it isn't our call.
What's actually different between Baseline and Pro?
Same technician, same measurements, same safety checks — those don't change based on what you pay. Pro adds the deep restoration work when your system needs it, unlimited free diagnostics, 20% off repairs instead of 10%, no after-hours surcharges, and $100 a year toward a new system.
Do I get the carbon monoxide check on the cheaper plan?
Yes. Combustion analysis is on both plans. We're not going to hold a CO test behind a paywall.
Do you check refrigerant pressure on a mini-split?
No — and neither should anyone else. Mini-splits have one service port, on the gas line. You physically can't calculate subcooling from it, and the inverter compressor changes speed constantly, so the pressure never sits still. We measure temperature split instead: room air in, supply air out. That number actually tells us something.
My mini-split smells. Is that mold on the coils?
Almost certainly not. On a mini-split the coil usually stays clean — the growth lives on the blower wheel, which is porous plastic sitting right behind a freezing cold coil. That's what we clean, and that's what stops the smell.
I have two systems. How does that work?
Two plans, or we'll build you one. Send us the setup and we'll run the numbers the same way we'd run them in your driveway.
What if I just bought a new system?
Then you're the ideal member — we keep it healthy from day one, and every year we've got a baseline to compare against. Your warranty probably requires annual maintenance anyway; we'll document it.
Do you service my area?
Vancouver, Camas, Washougal, Ridgefield, Battle Ground, Woodland, Hazel Dell, Five Corners, La Center — all of Clark County, WA.
Ready? Let's set it up.
Book your first maintenance visit online — pick a time that works. We'll confirm your system and set up the plan on-site before anything gets charged.
Why “Heisenberg”?
Werner Heisenberg (1901–1976) was a Nobel Prize–winning physicist and a founder of quantum mechanics, best known for the Uncertainty Principle — there's a hard limit to how precisely you can pin down two things at once.
Here's the thing about your HVAC system: there is no such limit. Every number that matters can be measured. Amps. Pressures. Static pressure. Temperature split. Carbon monoxide. Nothing about your system is genuinely uncertain — it's just that almost nobody bothers to look.
That's the whole plan, twice a year. We measure. You get the numbers. Nobody guesses.
The "30%" number everybody quotes has no source.
"A dirty condenser coil raises compressor energy use by 30%." That sentence is on hundreds of HVAC websites, always credited to the Department of Energy. We went looking for the study.
It is not in the FEMP Operations and Maintenance Best Practices Guide. It is not in DOE's Energy Saver material. It does not come up in a full-text search of DOE and national laboratory reports. Every site citing it points at another site that also cites nothing.
Here is a number that does have a source. Lawrence Berkeley National Laboratory measured the indoor coil — the evaporator — and found typical fouling costs under 5% in efficiency and capacity. Leave it twice as long and it runs 5 to 15%.
We would rather hand you the smaller number we can show you than the bigger one we cannot.
Siegel, Walker & Sherman, "Dirty Air Conditioners: Energy Implications of Coil Fouling," LBNL-49757, ACEEE Summer Study 2002
70 to 90% of systems in American homes have at least one fault.
That one is the Department of Energy's, and it is worth reading exactly as they wrote it: at least one performance-compromising fault "incurred at installation or due to inadequate maintenance." DOE does not split the two, because the underlying studies do not. Count duct leakage and the range goes to 90–100%.
So it is not "installed wrong." It is installed wrong, or never properly maintained, and in most houses nobody has measured which one.
That is the part we can fix.
Residential HVAC Installation Practices: A Review of Research Findings, U.S. DOE Building Technologies Office, June 2018
13,258 air conditioners were tested in California. 57% were outside spec on refrigerant charge.
Of the 8,873 residential systems in that group, 56% needed a charge correction. Correct means within 5% of what the manufacturer specifies, diagnosed by superheat or subcooling — not by how the line feels or how cold the air is at the vent.
The authors add something the people quoting them leave out: those numbers are too generous. Some technicians corrected the charge before phoning in the "initial" reading, so the real rate is worse than what got published.
There is a way to know instead of guess. It takes a gauge set and fifteen minutes.
Downey & Proctor, "What Can 13,000 Air Conditioners Tell Us?", ACEEE Summer Study 2002
Your system was rated at 0.10 to 0.20. Real houses run 0.38 to 0.55.
Equipment earns its efficiency rating in a lab, pushing against a set amount of duct resistance. The federal test procedure sets that at 0.10 inches of water column for units up to 2.4 tons, 0.15 up to 3.5 tons, and 0.20 above that.
Field studies compiled by the Florida Solar Energy Center and Proctor Engineering measured real installed systems between 0.38 and 0.55. Two to four times the resistance the rating assumed.
Undersized ducts. Choked return grilles. Your system has been breathing through a straw its entire life. The only way to know is to measure it.
Parker & Proctor, "Hidden Power Drains," FSEC-PF-361-01, ACEEE Summer Study 2000 · rating pressures per 10 CFR 430 Subpart B Appendix M / AHRI 210/240
A 30% undercharge is invisible. It costs 12% of your efficiency.
NIST measured it. Not modeled — measured, on a 2.5 ton heat pump, at a charge error field surveys turn up constantly. A 30% undercharge cut capacity by almost 15% and efficiency by 12%. Depending on conditions that day, the efficiency loss ran between 7 and 15%.
Low airflow does something similar and steadier. Cut airflow 30% and you lose about 6% efficiency, and that one holds no matter what the weather is doing.
You cannot feel either. The air still comes out cold. The system still runs. NIST adds a caveat we will repeat rather than bury: the same fault hits different systems differently — they cite one study measuring a 54% capacity loss where another measured 17%, at the same charge error. Which is the whole argument for measuring yours instead of quoting an average at you.
Domanski, Henderson & Payne, Sensitivity Analysis of Installation Faults on Heat Pump Performance, NIST Technical Note 1848, September 2014
Berkeley Lab tested duct tape on ducts. It failed catastrophically.
A national lab ran accelerated aging on 33 duct sealants. Cloth-backed, rubber-adhesive tape — the stuff actually called duct tape — "failed consistently, and often catastrophically." Some samples failed in days. Others took weeks. Heat is what kills it: none of the constantly cooled samples failed at all.
Mastic, butyl, foil tape with acrylic adhesive and aerosol sealant all passed.
The lab is careful about one thing, so we will be too. This was a bench test built to compare sealants against each other, not to predict how long yours survives in your attic. The comparison is the point. The tape is named after the thing it is worst at.
Walker & Sherman, "Duct Tape and Sealant Performance," LBNL-57225, 2005
The typical American duct system leaks 20 to 30% of the air it's carrying.
That range is the EPA's, stated plainly on the ENERGY STAR duct sealing page: about 20 to 30 percent of the air that moves through the duct system is lost to leaks, holes, and poorly connected ducts.
Berkeley Lab put a measured number next to it. Over a hundred California houses: 10% supply leakage, 12% return. About 22% of air handler flow.
We used to cite a third study here, on new homes in Colorado. We went looking for it and could not find it, and the figure attached to it contradicted the other two anyway. So it is gone.
You are paying to heat an attic.
ENERGY STAR / EPA, Duct Sealing · Sherman & Walker, LBNL-47214, 2002
A combustion analyzer finds heat exchanger problems faster than a teardown does.
Take a CO reading with the blower off, then turn the blower on. If the number moves, air is crossing somewhere it shouldn't — and now we know to go in and look.
It's a screening test, not a verdict. It tells us where to spend the 45 minutes, instead of spending them on every furnace and billing you for it. When the readings say open it up, we open it up.
Whatever your local gas utility's red-tag threshold is, we want to be well under it — and we'll show you the reading either way.
Method, not a study. This is the test as we run it — no source is cited because none is claimed.
In your mini-split, the blower wheel is the dirtiest part. Not the only one.
A 2023 study took apart the indoor units in 17 homes and swabbed the filter, the heat exchanger, the blower wheel and the vent, then measured fungal DNA in each. Every part carried a lot of it. The blower wheels carried the most.
That is not the same as saying it isn't on the coil. A wet coil catches roughly two thirds of what arrives. We used to say otherwise on this page. That was wrong, and this is the corrected version.
Taking the unit apart and washing it under pressure cut fungal load by more than 99% on every part. That is the measured result for the work we do. Nobody has run the comparison against cleaning in place, so we are not going to claim one.
Shiraishi et al., "A Method to Evaluate and Eliminate Fungal Contamination in Household Air Conditioners," Indoor Air, 2023 · coil deposition: Wu et al., Atmospheric Environment, 2016