Summer Home Inspections: Why HVAC Heating Can’t Always Be Tested

Summer Home Inspections: Why HVAC Heating Can’t Always Be Tested

Buying a home in the summer comes with its own set of challenges, especially when it comes to HVAC systems. One of the most common questions buyers ask during home inspections is: Can the heat pump’s heating mode even be tested on a hot day?

The short answer? Not always.

And depending on who you ask, an inspector, a contractor, or a seasoned HVAC tech, you might hear a slightly different version of the truth. Let's break it down.

What Is a Heat Pump and How Does It Work?

A heat pump is a dual-function HVAC system. In the summer, it works like an air conditioner, pulling heat from inside the home and releasing it outside. In the winter, it reverses direction, pulling heat from the outside air and pumping it inside to warm the home.

This switch in direction is made possible by a component called the reversing valve. It’s the heart of what allows a heat pump to operate as both a heater and an air conditioner.

Why Heating Mode Often Can’t Be Tested in the Summer

On hot days, typically when outdoor temperatures are above 85°F to 86°F, most heat pumps lock out the heating function. This is by design.

Why? Because trying to run a system in heating mode during high temperatures can damage internal components or trigger safety mechanisms. Some units will completely refuse to engage the heating cycle to avoid this risk.

This is why your home inspector might say, “I can’t confidently test the heating function today.”

And they’re not wrong.

Does That Mean You’re Buying Blind?

Not exactly.

Most heat pump systems use the same major components for both heating and cooling: the compressor, coils, and fan motors. The only difference in mode is how the refrigerant flows, controlled by that reversing valve.

So, if the air conditioning is running smoothly and cooling the home properly, many HVAC professionals will say that the odds are very high that the heating mode will function too, assuming the reversing valve is working correctly.

That’s the catch: if the reversing valve is stuck, damaged, or non-responsive, the system won’t be able to switch modes. And you won’t know unless the unit is tested in heating mode or inspected closely.

What Can You Do Instead?

If you’re in the middle of a home purchase and your heat pump’s heating mode can’t be tested due to outdoor temps, you still have options.

1. Hire an HVAC Technician, Not Just a Home Inspector

Home inspectors typically don’t have the tools or training to diagnose heat pump components in detail. A licensed HVAC technician can do the following:

  • Check refrigerant pressures
  • Test for valve functionality
  • Inspect sensors and safety controls
  • Simulate heating mode under controlled conditions

Many HVAC pros can even manually engage or bypass the reversing valve to confirm operation without damaging the system.

2. Wait Until Evening or Early Morning

If you’re still under inspection contingency and the outdoor temperature drops to the low 70s or below overnight, that’s your window to run the heating mode safely.

3. Ask for Service Records or Warranties

Request maintenance records from the seller or get a home warranty that covers HVAC. If the unit is relatively new and has been serviced regularly, the risk of a major failure is lower.

The Bigger Picture: HVAC Isn’t Just About Heat or Cool

This is also a good time to point out just how central HVAC is to the home buying experience, especially in summer.

A home’s HVAC system isn’t just about comfort. It affects:

  • Energy bills
  • Indoor air quality
  • Humidity control
  • Mold risk
  • Overall livability

When you’re buying in the middle of a heat wave, it’s tempting to focus only on whether the AC is pumping. But long-term, you need a system that’s reliable year-round.

Common Misunderstandings About Heat Pumps in Summer

Let’s clear up a few myths:

“If the heat doesn’t turn on in summer, the system is broken.”

→ False. Most systems are designed to not allow heating during high outdoor temps.

“If it cools, it must heat.”

→ Partially true. The heating and cooling modes share components, but the reversing valve is a variable that can still fail.

“The inspector should have been able to test it no matter what.”

→ Not true unless the inspector is also an HVAC tech and equipped to manually override the system safely.

Final Tip: Always Ask These Questions

Before closing on a home with a heat pump, ask:

  • How old is the system?
  • Has it been serviced in the last 12 months?
  • When was the reversing valve last checked?
  • What brand and model is it?
  • Is there a service contract or warranty?

Why HVAC Testing Matters Even More in Summer

It’s easy to overlook heating in the summer. But imagine moving into your new home in July, only to find out in December that your heat pump won’t warm your house, and you have no fallback system.

Testing and inspecting HVAC isn’t a seasonal luxury. It’s a must.

Even if full heating mode can’t be engaged, you can still inspect airflow, compressor strength, noise, refrigerant levels, and general system health.

Recap: What to Do if You Can’t Test the Heat

  • Don’t panic if the heating mode won’t engage during a hot inspection.
  • Confirm cooling performance, this tells you a lot.
  • Request a licensed HVAC technician, not just a home inspector.
  • Consider scheduling a second check early in the day or at night.
  • Use the situation to negotiate. HVAC repairs or tune-ups can often be covered by the seller or factored into the purchase.

Qualified HVAC Technician

If the cooling works well and the system’s components check out, you’re probably in good shape. Still, heat mode can’t be confirmed 100% without a temperature drop or a qualified HVAC technician. Don’t settle for a guess, get the inspection that gives you answers, not assumptions.

And remember, in the summer heat, your HVAC system isn’t just a feature, it’s your home’s front line defense against discomfort, high utility bills, and system failure.

HVAC Contractor Insurance and What to Look For

If you're hiring an HVAC technician during a home inspection, it helps to know they’re properly insured. This is especially true for inspections or repairs during escrow, where any mistakes or damage can delay closing.

In California, HVAC contractor insurance usually includes:

  • General liability coverage
  • Workers compensation
  • Commercial auto insurance

For HVAC professionals running their own operations, HVAC business insurance provides broader protection across multiple jobs, vehicles, and tools. Whether you’re a solo tech or managing a crew, having the best HVAC insurance in place helps protect your reputation and avoid costly issues.

Buyers working with licensed, insured HVAC professionals can move forward with more confidence. And contractors who carry the right coverage are more likely to be referred by real estate agents and trusted by clients.

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