Chat with one of our friendly reps to get help quick.

Something on your mind not found here? E-mail us.

We offer phone support if you don't want to type.

Support Center

<h2 id="isPasted"><u>Introduction</u></h2><p>The &quot;ATL&quot; error code indicates over-temperature protection. This article is for <a href="https://www.pioneerminisplit.com/collections/vertex-ducted-central-split" target="_blank" rel="noopener noreferrer">Vertex Ducted Central Split (DYC-18) systems</a>.&#xA0;</p><p><strong>Cause:&#xA0;</strong>The outdoor sensor T4 detects the ambient temperature is exceeding its range.&#xA0;</p><h2 id="troubleshooting-diagram"><u>Troubleshooting Diagram</u></h2><p><img src="https://attachments.gorgias.help/Q9r0k7BYaV2vg13y/hc/9JWjXVxG8m6DvMqm/2026020316-da26bdd8-2acf-435a-92ef-a892e804d675-dyc18_troubleshooting_atl.png" style="width: 800px;" class="fr-fic fr-dib fr-bordered"></p>

The "ATL" error code indicates over-temperature protection. This article is for Vertex Ducted Central Split (DYC-18) systems.

ATL Error Code

Troubleshooting

By Error Code

Error Codes for Vertex Ducted Central Split (DYC-18) Systems

Pioneer Offers Hyper-Heat Units

Pioneer Systems Offer Both Heating & Cooling Functions

Understand the Difference Between 115V & 230V Systems

Understand the Refrigerants Used for Each Model

How to Choose a System

Mini Splits are Capable of Using Fewer Indoor Units than the Outdoor Unit’s Zonal Capacity

Pioneer Mini Splits Function as Dehumidifiers

Pioneer Offers Different Lineset Lengths

Pioneer Offers Pre-Charged Linesets

Pioneer Offers Pre-Flared Linesets

Pioneer Systems Include Factory Pre-Charged Refrigerant

Single-Zone Mini Splits Cannot be Used with Multiple Indoor Units

Understand the Life Expectancy of Pioneer Systems

Understand how Mini Splits are Powered

Mini-Split Basics

Determine the Unit Size Needed for Your Space

Match the Lineset Diameter to Your Pioneer Indoor Unit

Understand Why Short Cycling Occurs When Sizing Systems

Sizing & Efficiency Guide

Start Here

Understand the Differences Between Inverter+ & Inverter++ Systems

Understand the Differences Between the Wall-Mounted Ductless Mini Splits

Understand Which Units are Rated Energy-Star

Compare Models

Learn About the Discounts Available

Learn About the Energy-Star Tax Credits Available for Pioneer Systems

Learn More about IRA Tax Credits

Learn Why Your Pioneer Discount Code Only Says "SAMPLE"

Redeem Your Pioneer Rewards Points When Shopping Online

Understand How to Manage Multiple Credit Card Charges with Pioneer

Financing & Payment

Learn About Our Shipping & Delivery Details

Understand the Qualifications for Free Shipping

Order Status & Shipping

Diamante Essenza High-Wall (WYT-17) Overview

Diamante Pro High-Wall (WYT-20) Overview

ECOasis 50 Wall-Mounted Energy Recovery Ventilator (ERV) Overview

ECOasis 150 Wall-Mounted Energy Recovery Ventilator (ERV) Overview

QHD070 High Performance Dehumidifier (QHD) Overview

Quantum Fresh High-Wall (WYT-FA) Overview

Quantum Hyperformance High-Wall (WYT-25) Overview

Quantum Ultra Ceiling Cassette (CYT-24) Overview

Quantum Ultra Ducted Ceiling Concealed (RYT-24) Overview

Quantum Ultra Floor-Ceiling Flex (UYT-24) Overview

Quantum Ultra High-Wall (WYT-24) Overview

Quantum Ultra Multi-Zone Overview

RV Rooftop Inverter (PYZ) Overview

RV Under-Bench Inverter (PYR) Overview

Vertex Ducted Central Split (DYC-18) Overview

Product Line Overviews

Find Out How to Complete Returns

Figure Out How to Start Your Return

Learn About Our Policy for Undeliverable or Refused Shipments

Learn About Our Return Policy

Understand How to Return an Item

Understand the Eligibility Requirements for Refunds

Understand Our Return Fees

Understand Our Return Process

Returns & Refunds

Shopping & Pre-Purchase

Find an Installer for Your System

Find Professionals to Install Your Pioneer System

Learn Who is Permitted to Install Your System

Understand if Our Systems can be Self-Installed

Understand the Cost & Time Spent on Installing Systems

First-Time Setup

Connect the Drain Hose for LCAC Systems

Connect the Refrigerant Piping to the Indoor Unit

Install the Decorative Panel for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Prepare the Ceiling & Install the Hanging Hook for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Select the Indoor Unit Installation Location for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Set Up the Indoor Unit Condensate Piping Connections for Quantum Ultra Ceiling Cassette (CYT-24) systems

Suspend the Air Handler Unit for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Understand the Additional Leakage Sensor for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Understand the Air Duct Parameters for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Wire the Indoor Unit & Decorative Panel for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Wrap the Lines & Seal the Air Gaps for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Cassette Units

Ceiling Concealed

Central Split

Ducted Units

Drill the Piping Wall Hole for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Mount the Indoor Unit to the Ceiling for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Mount the Indoor Unit to the Floor for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Prepare the Refrigerant Piping of the Indoor Unit for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Select the Indoor Unit Installation Location for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Set Up the Indoor Unit Condensate Piping Connections for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Understand the Additional Leakage Sensor for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Wire the Indoor Unit to the Outdoor Unit for Quantum Floor-Ceiling Flex (UYT-24) Systems

Wrap the Lines & Seal the Air Gaps for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Flex Units

Connect the Drain Hose for Quantum Fresh (WYT-FA) Systems

Connect the Drain Hose for Wall-Mounted Systems

Connect the Fresh Air Pipe for Quantum Fresh (WYT-FA) Systems

Drill the Piping Wall Hole for Wall-Mounted Systems

Install the Indoor Unit Mounting Plate for Wall-Mounted Units

Prepare the Refrigerant Piping of the Indoor Unit for Wall-Mounted Systems

Select the Indoor Unit Installation Location for Quantum Fresh (WYT-FA) Systems

Select the Indoor Unit Installation Location for Wall-Mounted Systems

Understand the Additional Leakage Sensor for Wall-Mounted Systems

Wire the Indoor Unit for Wall-Mounted Systems

Wrap the Lines & Mount the Indoor Unit for Wall-Mounted Systems

Wall-Mounted Units

Indoor Units

Angle Linesets Upward

Complete the Safety Checks & Test Run

Find Out if a Wall-Mounted Indoor Unit can be Set onto Ceilings

Find Out if the Indoor Unit Requires Anything Extra in Order to be Wall-Mounted

Find Out the Ideal Height for Mounting Indoor Units

Leakage Inspection & Vacuuming for Refrigerant Lines

Learn the Gauge of Wire Used for Ductless System Connections

Open the Service Valve

Setup the Lineset to Exit from the Side of the Indoor Unit

Understand 6-Foot Plastic Whips & 4-Lead Mini Split Connection Wire

Understand how to Properly Uncoil the Lineset

Understand the Drilling Details to Accommodate Drain & Refrigerant Lines

Understand the Requirements for Installing Your System

Understand the Torque Wrench Size for Installing Your System

Installation Requirements

Understand the Meaning of “Multi-Zone”

Multi-Zone Units

Air Evacuation & Bleeding the Circuit

Connect the Power/Signal Electrical Wiring to Outdoor Units

Connect the Refrigerant Piping to the Outdoor Unit

Mount the Outdoor Unit

Select the Installation Location for Outdoor Units

Select the Outdoor Unit Installation Location for Vertex Ducted Central Split (DYC-18) Systems

Set Up the Condensate Water Drainage for Outdoor Units

Understand how to Install Outdoor Units on Support Pads for Vertex Ducted Central Split (DYC-18) Systems

Outdoor Units

Create the Roof Opening

Install the Air Duct & Top Mounting Plate

Mount the Panel

Place the Unit onto the Roof

Setup the Electrical Wiring for RV Rooftop Systems

Setup the System Connections for RV Rooftop Systems

Understand the Installation Requirements for RV Rooftop Systems

RV Units

Installation & Setup

Understand the DIP Switches for Vertex Ducted Central Split (DYC-18) Systems

DIP Switch Layouts

Turn the LED Display On or Off

Understand the Display Panel for RV Rooftop Systems

Understand the Display Board for Quantum Ultra Ducted Ceiling Concealed (RYT-24) Systems

Understand the Front Panel Displays for Quantum Ultra Ceiling Cassette (CYT-24) Systems

Understand the Front Panel Display for Quantum Ultra Floor-Ceiling Flex (UYT-24) Systems

Understand the Front Panel Display for Wall-Mounted Systems

Display Layouts

CL error code

Clean the Anti-Dust Filters for Diamante Essenza & Pro Systems

Clean the Anti-Dust Filters for Quantum Fresh Systems

Cleaning the Anti-Dust Filters for Quantum Ultra Ceiling Cassette Systems

Clean the Anti-Dust Filters for Quantum Ultra Ducted Ceiling Concealed Systems

Clean the Anti-Dust Filters for Quantum Ultra Floor-Ceiling Flex Systems

Clean the Anti-Dust Filters for Quantum Ultra High Wall-Mount & Hyperformance Systems

ATL Error CodeUpdated 4 days ago

Introduction

Troubleshooting Diagram