HVAC Struggles in Summer? Why Upgrading Your System Isn’t Always the Answer

HVAC Struggles in Summer? Why Upgrading Your System Isn’t Always the Answer

If your upstairs turns into a sauna every summer while the AC runs nonstop, you’re not alone, and your HVAC system might not be the root of the problem.

Many homeowners, especially those living in older homes with little to no insulation, assume the fix is simple: replace the system. But even the best HVAC unit won’t perform miracles if your home is working against it.

Let’s break down what’s really happening, what HVAC professionals aren’t always upfront about, and how insulation, air sealing, and smarter upgrades can have a bigger impact than you think.

What Happens When You Run AC in an Inefficient Home

In older homes, think early 1900s American Foursquare builds with original windows and little to no wall insulation, cool air doesn’t stay inside. These homes were designed to breathe, meaning they were built for airflow long before air conditioning was even invented.

That means:

  • Cool air leaks out through drafty windows and uninsulated walls
  • Hot, humid air seeps in from every direction
  • Your AC runs constantly, but can’t cool the space efficiently
  • Upstairs temperatures still climb into the high 70s or low 80s by the end of the day

And if your HVAC system is over 15 years old and uses outdated refrigerant, you’re also looking at limited options and rising costs just to keep it running.

Is an 18–20 Degree Cooling Limit Real?

Yes. Most air conditioning systems, including heat pumps, are designed to cool indoor air by about 18 to 20 degrees compared to the outdoor temperature.

So when it’s 98°F and humid in Virginia? Getting your upstairs below 78–80°F might already be pushing your system to its limit, even if it’s brand new.

That might sound frustrating, especially if you're about to drop thousands on an upgrade. But oversizing the system isn’t the answer either.

Why Bigger Isn’t Better in HVAC

Installing a larger unit might sound like a quick fix, but an oversized system introduces a host of problems:

  • Short cycling – The unit cools the air quickly, then shuts off before it can remove humidity. The result: rooms that feel clammy and inconsistent.
  • Mold and condensation – Larger systems dump cold air into hot, humid rooms too fast. Moisture builds up in the ducts and vents. It can condense on walls, ceilings, and inside your HVAC system, especially in homes with poor insulation.
  • Higher energy bills – Bigger units burn more power and have more frequent start-stop cycles, which is inefficient and expensive.
  • Structural damage – Persistent moisture buildup can lead to warped floors, peeling paint, and actual water damage over time.

So What’s the Real Fix?

Start with the structure of the home, not the hardware.

1. Get an Energy Audit

A professional energy audit identifies where air is leaking, where insulation is lacking, and which fixes will give you the highest return.

Even something as simple as caulking drafty windows or sealing attic gaps can immediately reduce heat gain.

2. Air Sealing and Insulation

Before touching the HVAC unit, focus on keeping the air inside.

  • Blow insulation into uninsulated walls (many older homes don’t have any)
  • Add attic insulation if it’s minimal or outdated
  • Air seal around windows, doors, outlets, and ducts
  • Consider storm windows or double-paned replacements

These changes are often cheaper than a full HVAC replacement, and have a massive impact on temperature regulation.

3. Window Treatments

Sunlight contributes heavily to solar heat gain. Use blackout curtains or thermal blinds on east- and west-facing windows. This is an easy, low-cost upgrade that reduces indoor temperatures by several degrees.

What About Replacing the HVAC System?

If your system is 17+ years old, inefficient (SEER 10 or lower), or running on discontinued refrigerant, a replacement is smart eventually, but not as a standalone fix.

Replacing your system before it fails can help avoid emergency fees. But if your home leaks air like a sieve, the new system will still struggle.

An experienced HVAC professional should:

  • Inspect the ducts for leaks or airflow issues
  • Measure and calculate the correct system size (called a Manual J load calculation)
  • Check that your second-floor heat pump is configured for cooling mode
  • Be upfront about what a new system can and can’t do in an inefficient structure

Should You Go Ductless?

In homes with inconsistent airflow or outdated ductwork, a ductless mini-split system can be a better choice. Instead of pushing air through a central system, each room gets its own blower unit, which:

  • Increases control over each space
  • Reduces air loss through leaky ducts
  • Prevents moisture buildup in unused rooms
  • Lowers energy usage with targeted cooling

This isn’t always necessary if your ducts are in good shape, but it’s worth considering for homes with uneven cooling, poorly designed vents, or historic layouts.

Real Talk: Not All HVAC Companies Are Equal

Some companies will quote you over the phone without even seeing your home. Others will send someone out, punch a test hole in your ductwork, measure airflow, and explain exactly how your system behaves in real-world conditions.

The second group may charge more, but you’re paying for experience, not guesswork.

If a technician talks you out of buying a bigger system, they’re probably worth listening to.

HVAC Insurance Coverage, Behind the Scenes

When you're investing in repairs or replacements, make sure you're working with a fully insured HVAC contractor. This protects both your home and the professional doing the work.

For contractors, the right insurance coverage builds trust and protects against costly liability.

Here are the most common types of HVAC insurance:

  • HVAC contractor insurance California – This usually includes general liability, commercial auto, and workers comp tailored for contractors in California.
  • HVAC business insurance – Covers your equipment, job site risks, and client claims across multiple properties or service areas.
  • Best HVAC insurance – Typically bundles property protection, professional liability, and completed operations coverage in one affordable policy.

If you’re a contractor bidding on jobs in older homes, insulation retrofits, or heat pump installations, carrying the right HVAC business insurance isn’t optional. It’s a signal that you’re professional, prepared, and serious about safety.

Recap: When HVAC Isn’t the Problem

If your AC can’t keep up in the summer, but your furnace works great in winter, the issue is probably structural, not mechanical.

Before replacing your system:

  • Get an energy audit
  • Add insulation and seal leaks
  • Reduce solar heat gain with window treatments
  • Confirm your current system is properly configured
  • Avoid oversizing at all costs

If you do upgrade your system, make sure it’s sized correctly, installed by an insured professional, and paired with improvements to your home’s envelope. Otherwise, you’re just cooling the outdoors.

Hire an HVAC Professional

You’re not crazy for wanting your upstairs to stay below 80°F in July. But in homes built before air conditioning existed, the solution isn't always a bigger system. It’s a better strategy.

That means tightening up the structure, upgrading what matters, and working with HVAC professionals who actually know how to balance comfort, humidity, and system health, especially during brutal summer heat.

HVAC Insurance Coverage, What Pros Should Carry

Homeowners should always ask whether their HVAC contractor is insured, especially during major repairs or full system replacements. Insurance protects you in case of property damage, injury, or unexpected issues.

Professionals offering HVAC services in California need proper coverage to stay compliant and protect their operations. This includes: 

  • HVAC contractor insurance California – A must for anyone doing installs, repairs, or maintenance across the state. Typically includes general liability,
  • HVAC workers compensation insurance, and commercial vehicle coverage.
  • HVAC liability insurance – Covers accidental property damage or bodily injury during a job.
  • HVAC business insurance – Broader coverage for equipment loss, customer disputes, and job site claims.
  • Small business HVAC insurance – Scaled coverage for solo operators or crews with fewer than five techs.
  • Affordable HVAC insurance options – Packages that protect while keeping overhead low.
  • Best HVAC insurance providers – Offer flexible policies tailored for the seasonality and risk of HVAC work.

If you're a contractor, insurance for HVAC contractors isn't just a formality, it protects your tools, your crew, your clients, and your future.

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