I've been the procurement manager here for about six years. Our company is small—40 people, metal fabrication, just outside Boston—and I'm the one who tracks every invoice, every filter order, every service call. When I audited our 2023 spending, I found we'd spent more on reactive HVAC service calls than on planned maintenance. That stuck with me.
The call came in at 6:40 a.m. on a Wednesday in May 2024. Our building manager, Rick, was standing in front of the McQuay chiller that cools the welding side of the plant. The display was blinking at a password prompt, and nobody had the password. The chiller wouldn't start.
I know McQuay chillers are solid pieces of equipment. We've had ours for 12 years. But I also knew a locked controller is a downtime event, and downtime is the most expensive line item we rarely put on the budget. Why does that matter? Because at 8 a.m., the shop floor needed cold water for the weld lines. By 9, the maintenance guy was standing behind Rick with a phone number for our regular HVAC vendor.
The vendor said they could send a technician in two days. The quote was $1,850, plus parts, plus a 'diagnostic fee.' I didn't say yes. Part of me wanted to say yes just to get it done. Another part remembered what happened the last time we signed off on a flat-fee service call without asking what it actually covered. The question I asked was simple: was this the only option?
The office manager didn't love that question. 'We're not in the habit of holding hands over the phone.' In my opinion, that's exactly when a small customer needs a vendor to pick up the phone. Small orders almost never get the same attention unless you push a little. I'm not saying every service vendor has to give us free consulting. But the 'your problem is boring' tone is a real cost, because we're still going to need parts and service later.
So I started searching 'mcquay chiller password' while Rick pulled manuals from the electrical room. That search led me to the controller model: a MicroTech II. It also led to a forum thread that said something I should have remembered. The password isn't some hidden backdoor; it's an access level that the installing contractor sets. If your contractor never left the password, the manufacturer can verify that you own the unit and help you reset it.
Don't hold me to those forum details, because I'm not a controls technician. But the important part was in the manual: McQuay is now part of Daikin Applied, and as of May 2025, they still provide legacy documentation for McQuay chillers. I'm not 100% sure of the exact URL, but a phone call to technical support confirmed what I was reading. They verified the serial number, walked Rick through the reset, and in about 20 minutes we had the chiller back in auto mode.
Even after we did the reset, I kept second-guessing. What if we'd messed up a control parameter? What if the chiller ran but drew too many amps? The two hours between reset and the compressor actually starting felt like two days. I didn't relax until the supply-water temperature began pulling down and the amp draw looked normal.
What is a heat exchanger?
That afternoon, after the chiller was running, a new maintenance hire asked me, 'What is a heat exchanger, anyway?' It sounded like a simple question. It isn't.
A heat exchanger moves heat from one fluid to another without mixing them. In a chiller, you've got two of them doing the heavy lifting. The evaporator takes heat out of the building water loop and transfers it into the refrigerant. The condenser rejects that heat to the outside air, or to a cooling tower, depending on your setup. If fouling builds up inside those tubes, heat transfer gets worse and the chiller works harder. That's a cost problem, not just a mechanical problem. For anyone searching 'what is a heat exchanger' for the first time, the core idea is simple: two fluids pass near each other, heat moves from the warmer one to the cooler one, and they don't mix.
A note about filters (yes, the 16x20x1 air filter)
While we were in the mechanical room, someone suggested we replace the 16x20x1 air filter in the air handling unit with a K&N air filter. I get the appeal—clean it, reuse it, buy once. But the K&N air filter in a truck is not the same conversation as an HVAC filter. An engine filter is made to let a lot of air through. An HVAC filter is there to protect the coil and maintain some level of indoor air quality. Some K&N products are designed for residential HVAC, but our commercial unit needs a specific MERV rating. We stuck with MERV 8 pleated 16x20x1 air filters and put them on the schedule. If you ask me, that's the safe call.
What it actually cost us
The service call that would have been $1,850 ended up costing us about $180 in materials and four hours of Rick's time. We also bought a couple of replacement filters for $42. And we found a local parts supplier who treated our small order like a real order. That's the part I want to underline: the price of a part matters less than the relationship.
Looking back, the password itself was never the real problem. The real problem was that we didn't have a documented turnover package from the previous contractor. We had the manual, but nobody in the building had ever opened the access-level page. If we'd taken thirty minutes to record passwords and controller settings, we would have saved a full morning. This is the part that makes my spreadsheet brain happy. The total cost of the episode was not the $180 in materials or the four hours. It was the risk that we were one bad decision away from a $1,850 invoice. Total cost includes risk, and risk is hard to put in a cell.
I have mixed feelings about sharing all this. On one hand, I don't want anyone to skip a qualified technician when they're truly stuck. On the other hand, I do not want small-facility buyers to assume every locked controller is a reason to write a big check. It depends on the controller, your skills, and whether you have the original documentation.
Three lessons I'll keep
- Write down every password. In 2022, we changed contractors and the previous one took their access with them. That's on us for not documenting it.
- Price is not the same as cost. The $1,850 quote might have been fair if we couldn't solve it ourselves. But 'fair' doesn't mean 'necessary.' I'd rather pay for a diagnostic visit with clear terms than a flat fee with fine print.
- Small orders are still relationships. We bought two filters from a supplier who answered the phone and shipped the same day. That supplier will get the bigger order later.
If you ask me, the real cost of any piece of equipment is the cost of ignoring the details. A chiller password seems small. A filter seems small. A heat exchanger question seems small. But small things compound. That's the lesson I keep coming back to, and it's the one I want to pass along.
