Restaurant AC Not Working: Common Causes and Solutions

Restaurant AC Not Working: Common Causes and Solutions

A malfunctioning AC unit can be a major headache for any restaurant owner, especially during the hot summer months. Not only can it make the dining experience uncomfortable for customers, but it can also lead to food spoilage and other health hazards. In this article, we’ll delve into a common AC issue that often plagues fast food restaurants and discuss how to identify and fix the problem.

The Problem: A Secondary Tray Filled With Water

One frequent culprit behind a non-functional AC unit in fast food restaurants is a secondary tray filled with water. This tray is designed to collect condensation from the evaporator coils, a vital part of the AC system. When the tray becomes full, it can trigger a float switch, interrupting the low-voltage circuit that powers the AC unit.

Why Does This Happen?

The accumulation of water in the secondary tray can be attributed to several factors:

  • Clogged Drain Line: The drain line is responsible for carrying the condensation away from the evaporator coils. If it becomes clogged with debris, the water will back up into the tray.
  • Evaporator Coil Problems: A dirty or damaged evaporator coil can lead to excessive condensation, overwhelming the drain line and filling the tray.
  • Refrigerant Leak: A refrigerant leak can cause the evaporator coils to freeze, leading to increased condensation and water buildup.

Identifying the Issue

To determine if a full secondary tray is the cause of your AC problem, check the following:

  • Look for a water puddle: If there’s a puddle of water underneath the AC unit, it’s a strong indicator that the tray is overflowing.
  • Inspect the drain line: Check the drain line for any blockages or leaks.
  • Listen for unusual noises: A gurgling sound coming from the AC unit might signal that water is backing up in the tray.


Once you’ve identified a full secondary tray as the issue, there are several solutions you can implement:

  • Clean the drain line: Use a wire hanger or a specialized drain cleaner to remove any debris from the drain line.
  • Clean the evaporator coil: Clean the evaporator coil with a coil cleaning brush and a solution of water and detergent. Avoid using harsh chemicals that could damage the coil.
  • Check for refrigerant leaks: If you suspect a refrigerant leak, call a qualified HVAC technician to inspect and repair the system.

Preventing Future Problems

To prevent future issues with your restaurant’s AC unit, consider these preventative measures:

  • Regular maintenance: Schedule regular maintenance checks for your AC unit to ensure it’s functioning properly and to identify any potential problems before they become major issues.
  • Clean the drain line regularly: Clean the drain line at least once a month to prevent clogs.
  • Keep the evaporator coil clean: Clean the evaporator coil every few months to prevent dust and debris buildup.


A malfunctioning AC unit can be a major inconvenience for your restaurant, but with proper identification and troubleshooting, you can quickly restore your system to working order. By understanding the common causes of AC problems and implementing preventative measures, you can ensure a comfortable dining experience for your customers and avoid any potential health hazards.