In New Mexico, there are windows of time when an HVAC unit can be shut down without anyone in the building noticing. September and October are usually among them. The demand for AC is dropping in September, and the heating season hasn’t quite started yet. Additionally, your HVAC unit has just spent the last four months telling you how much life it has left in it. If HVAC replacement is on your mind for the next 12 to 18 months, September is a great time to start planning.
The Four-Month Stress Test
Summer is the most honest diagnostic you can put your building through. Everything your system can’t do shows up between May and August, and in September the evidence is still fresh. Record these five things before the details fade from your memory.
- Tenant complaint logs. Note which units never seemed to get comfortable, even after a service visit.
- Utility bills. Compare this summer to last summer with occupancy held steady. Rising consumption could point to declining efficiency.
- Service history. Look for the same unit appearing on multiple invoices in a single season. Repeat calls are a pattern you should pay attention to.
- HVAC unit data. Note the age, tonnage, and refrigerant type for every unit.
- Runtime behavior. Units that ran nearly continuously through July are carrying a load they can’t handle.
What You Need to Know About Equipment Lead Times
When it comes to replacing an HVAC unit, the install date isn’t the most important thing to pay attention to. The order date typically matters more. Packaged rooftop units with specific tonnage, economizers, curb adapters, or building-automation compatibility aren’t usually stocked in a warehouse somewhere. They get built and shipped on a schedule that has nothing to do with your install date.
Before you sign a contract, ask for the current lead time in writing alongside the price. Ordering in September generally means a fall or early-winter install. Ordering in November can mean living with an old unit through another heating season.
September Aligns with Budget Season
At this time of year, most property managers are building next year’s capital outlay plan or defending this year’s remaining budget. Replacement planning fits into both of those conversations. But you’ll need real numbers, not placeholders.
A scoped quote will account for structural work, electrical, controls, crane time, disposal, and permitting. That way, when you bring the request to management, you have solid numbers to back you up, not a rough estimate you found online. You should also ask for any current utility efficiency rebates that apply to the equipment you are considering.
Repair or Replace?
There is no universal formula for deciding when it’s time to replace a unit instead of repairing it. But some signals tend to show up alongside each other.
- Repair costs are approaching a meaningful share of the replacement cost.
- The unit is well into its expected service life.
- Tenant complaints about comfort continue after the repairs are done.
- Parts are getting hard to source.
- You’re already planning a related project.
What To Do This Month
Planning doesn’t mean you’re committing to a new unit. Here’s a quick five-step process you can do this month.
- Walk the roof with your service provider.
- Rank each unit by risk, not age. A 10-year-old unit serving your largest building may outrank a 15-year-old unit used for a storage area.
- Get a scoped quote with lead times.
- Document the install window.
- Build a maintenance plan for units that are not being replaced.
Replacing equipment on your schedule almost always costs less and is less disruptive to tenants. September is the last comfortable window before the heating season starts.
At Aztec Mechanical, we’ve been designing, installing, and servicing commercial HVAC systems in New Mexico since 1977. If replacement is on your mind, schedule a walkthrough with our team. We’ll help you build a plan on your schedule.
Frequently Asked Questions
Is September too late to replace a commercial HVAC unit before winter?
No — September is early enough for most projects, which is exactly why it works. The constraint is equipment lead time, not weather. Starting the quote and order process now generally allows for a fall or early-winter install, while waiting until heating season begins usually pushes the work into the following year.
How long should a commercial rooftop unit last in New Mexico?
Service life varies by equipment type, maintenance history, and how hard the unit has been run. New Mexico conditions, including high altitude, heavy dust, and wide daily temperature swings, tend to be tougher on equipment than milder climates. A technician reviewing the unit’s nameplate data and service record can give you a realistic remaining-life estimate for your specific system.
Should I replace all my rooftop units at once or phase the work?
Phasing is common and often smarter for cash flow, but it needs a plan. Rank units by risk and by which tenants they serve, replace the highest-risk equipment first, and put the remaining units on a maintenance agreement so they stay reliable while they wait. Replacing everything at once can make sense when the units are the same age and a single mobilization saves significant crane and labor costs.
