How a Misleading Thermostat Reading Masked a Frozen System

When a homeowner in Mills River, NC noticed their home getting uncomfortably warm, they initially suspected an issue with their thermostat. The digital readout wasn’t reaching the desired set temperature, and the home’s indoor air conditioning seemed to have completely given out. They reached out to get to the bottom of the issue and bring back their indoor comfort.

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Problem:

A simple thermostat complaint that uncovered a frozen system.

Upon arrival at the Mills River home, our service technician conducted a comprehensive system diagnostic. While the customer’s initial complaint pointed toward a faulty thermostat, the true culprit was hiding directly inside the indoor equipment.

The Frozen Reality: When verifying the indoor air handler, our technician discovered that the evaporator coil was completely frozen solid into a massive block of ice.

The Thermostat Misconception: When an HVAC system freezes up, it completely loses its ability to transfer heat. Because the system can no longer drop the indoor air temperature, the thermostat runs continuously without relief—giving the illusion that the thermostat itself is broken when it is actually just waiting on a frozen system.

The Root Causes: Evaporator coils typically freeze solid due to one of two critical failures: severe indoor airflow restriction or a major system refrigerant leak.

Solution:

A Complete 2-Ton York AC & Gas Furnace Revamp

???? Install Date: 6/23/2021
???? Time to Complete: 10 Hrs
???? Total Investment: $7,232.00

To permanently resolve the freezing issue and secure long-term comfort, we installed a fully matched, high-efficiency split system:

We replaced the old outdoor unit and frozen indoor coil with a brand-new 2-ton York central air conditioning system and matching indoor cooling coil to permanently stop the cooling failures.

To ensure reliable whole-home comfort, we replaced the aging furnace with a 80% AFUE York gas furnace designed for quiet, efficient operation.

We installed a Honeywell T6 Pro programmable thermostat. configured specifically for a conventional 1-stage cooling and 1-stage heating schedule. This seamlessly bridges the communication between the furnace and the AC.

To fortify the new installation, we secured a proper HVAC permit, stabilized the equipment on a fresh outdoor pad, and added an auxiliary condensate pump with a safety float switch to protect the home against potential future water damage.

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Why Was This the Best Choice?

A brand-new condenser and matched coil completely remove the old mechanical failures that caused the initial ice buildup. The addition of a new condensate pump and safety float switch ensures that if a drain line ever backs up, the system will safely shut down before moisture can overflow into the home. The new system comes backed by an exceptional warranty package, including 10-year parts coverage, 10-year compressor coverage, and 10-year labor backing. The project also included a complimentary 1-year complimentary membership agreement ($199 value) to keep everything running smoothly.

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4 Tips for Homeowners Protecting Their Climate Systems

Shut Off a Constant System

If your home is warm but the system keeps running without cooling down, turn it off immediately. Forcing a frozen indoor unit to run continuously can destroy the compressor, turning a simple diagnostic visit into an emergency replacement.

Check for Ice Early

Regularly inspect your indoor unit and outdoor copper lines for any white frost or ice buildup. Freezing is an obvious warning sign of a hidden refrigerant leak or completely blocked airflow that requires professional evaluation.

Install Flood Safety Switches

Always make sure your system has an inline float switch and a functional condensate pump. A thawing system produces an incredible amount of water, and these small components automatically shut down the system to save your floors from massive water damage.

Never Skip Labor Coverage

While standard equipment warranties cover replacement parts, specialized mechanical labor rates can still result in high out-of-pockt bills. Protect your wallet by prioritizing installations that bundle a long-term labor warranty alongside regular annual maintenance.

Think you might need to replace your unit soon? Check out our Homeowner’s Guide on HVAC replacements!

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