New AC Not Cooling Right? Signs of a Poor Install and What a Second Opinion Checks
You paid for a new air conditioner or heat pump, and the house still won’t cool down. Maybe the upstairs never gets comfortable, the air coming out of the vents isn’t very cold, or the system runs all afternoon without catching up. That’s frustrating, and it’s more common than it should be.
A new system that doesn’t perform usually isn’t a bad unit. Far more often, something about the installation or setup is off: airflow, refrigerant charge, ductwork, drainage or settings. Those problems can be found and measured. This guide explains what you can check yourself, what a second opinion should measure, and how to handle it with your original installer.
Want a professional check? Comfort Medics evaluates newly installed systems from other companies for $100. If you’re still deciding on a replacement and want a second opinion on a quote, that one is free.
First: Give It a Fair Test
Some expectations are worth resetting before you assume something is wrong.
- On a very hot afternoon, a correctly sized system may run for long stretches. Running a lot is not the same as not working.
- After a long time off, it can take hours to pull heat and moisture out of the house, especially upstairs.
- Bigger isn’t faster in the long run. An oversized system can cool quickly and still leave the house clammy, because it shuts off before it removes much humidity.
If the house still won’t reach the set point on a normal summer day, or it feels damp and cool instead of comfortable, there’s likely a real problem.
What You Can Safely Check
- Thermostat: set to Cool, fan on Auto, set point below room temperature. A new thermostat may also have setup options (system type, stages, fan settings) that were configured during installation. Don’t change installer settings you don’t understand, but do note what they are.
- Filter: new systems sometimes ship with a filter that’s the wrong size or a restrictive type for your returns. Make sure it fits and isn’t already dirty from construction dust.
- Registers and returns: open, unblocked by furniture or rugs.
- Outdoor unit: running when the system calls for cooling, fan spinning, nothing piled against it.
- Ice: frost or ice on the refrigerant lines or indoor coil means airflow or charge is off. Turn cooling off and let it thaw, and call.
- Water: water around the indoor unit, a full secondary pan or a tripped float switch means the condensate drain isn’t working. Turn cooling off to avoid ceiling damage.
Don’t open sealed panels, add refrigerant or adjust anything inside the units. That’s work for a licensed technician.
Call Your Installer First
If your system is new, the company that installed it should get the first chance to fix it, and your labor warranty may depend on it. Call, describe exactly what you’re seeing and when, and ask what they measured at startup. A good installer will have readings to share.
Also check that the equipment has been registered with the manufacturer. Many parts warranties require registration within a set window after installation.
A second opinion makes sense when the installer can’t find the problem, keeps returning without fixing it, can’t tell you what was measured, or isn’t returning your calls.
Signs of an Improper HVAC Installation
You can’t see refrigerant charge or static pressure, but some clues of a rushed or incomplete installation are visible:
- Noise from the start: a new system that whistles at the return grille or roars at the vents may be fighting restrictive ductwork.
- Ice within days or weeks: frost on the refrigerant lines or indoor coil on a new system usually points to low airflow or an incorrect charge.
- Water where it shouldn’t be: a dripping secondary pan, a wet ceiling below an attic unit or a drain line with no slope.
- Loose ends outside: refrigerant lines with missing or torn insulation, an outdoor unit that isn’t level, or a disconnect with no cover.
- No paperwork: no permit, no equipment model numbers on your invoice and no record of what was measured at startup.
None of these proves the system was installed badly, but each one is worth asking about. A properly commissioned system is verified with measurements before the installer leaves. That’s what our Installation Standard covers on every Comfort Medics install, as applicable to the equipment.
What a Real Second Opinion Measures
A useful second opinion is based on measurements, not a glance at the outdoor unit. At Comfort Medics, we evaluate a poorly performing system against the same checks we use on our own installs, the Comfort Medics Installation Standard, as applicable to the equipment:
Airflow and ductwork
- Total external static pressure, which shows whether the ducts and filter are choking the blower
- Blower speed and equipment settings
- Duct layout, restrictions, undersized returns, and disconnected or crushed ducts in the attic
Airflow problems are among the most common causes of a new system underperforming. The equipment can be fine and still be starved for air. Our airflow and ductwork section explains why it matters.
Refrigerant charge and commissioning
- Charge checked with superheat and subcooling against the manufacturer’s targets
- TXV operation, where the equipment has one
- Whether the indoor coil properly matches the outdoor unit
- Signs of a leak or of a system that wasn’t evacuated properly
Electrical, controls and drainage
- Supply voltage and amp draws
- Control-board and thermostat configuration
- Condensate drainage and overflow protection
Paperwork
- Whether a permit was pulled and the inspection completed
- Equipment model numbers, so you know what was actually installed
We’ll show you what we find and explain it in plain terms. Sometimes the fix is an adjustment. Sometimes it’s ductwork. Occasionally the equipment itself doesn’t suit the house. Whatever it is, you’ll know what’s wrong and what your options are.
Common Causes We Look For
- High static pressure from undersized ducts, too few returns or a restrictive filter
- Incorrect refrigerant charge because the system was charged without being measured
- Blower set to the wrong speed for the equipment
- Mismatched indoor and outdoor components
- Leaky or disconnected attic ducts dumping cool air into the attic
- Condensate problems that trip a float switch and shut cooling down
- Thermostat misconfiguration for the type of system installed
Many of these also explain why the upstairs is hotter than downstairs.
Heating Season Works the Same Way
A new heat pump that won’t keep up in winter, or a new furnace that turns on and off constantly, deserves the same measured approach. For furnaces, see furnace short cycling: causes and fixes.
If It Needs to Be Redone
If the problem can’t be corrected and replacement is the right answer, our HVAC replacement and installation page explains how we install, configure and commission air conditioners and heat pumps. New Comfort Medics systems include a 10-year manufacturer parts warranty on qualifying equipment (registration may be required), a 10-year labor warranty and a lifetime craftsmanship guarantee.
Get a Second Look
Comfort Medics Heating & Cooling is a family-owned, licensed and insured Georgia contractor (GA. REG. CR2011437) serving North Georgia from Kingston. We measure instead of guessing.
Want us to take a look? Request a second opinion, and see how second opinions work on our HVAC replacement and installation page.
Call (470) 360-8887 Request a Second Opinion
