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249 VAN Launch Kit 249 VAN Consumer Brochure Smart Thermostat Sell Sheet 249 VAN Launch Kit

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This installation was on a 4-story home, and the tech had not yet gone to the basement to troubleshoot the “infinity” water source heat pump, as he was told he by the homeowner. He was in the attic at the infinity furnace above the 4th floor. He was getting his dcv in the proper range on his A and B green plug on the air handler, 3 to 4 vdc. His indoor board ohm reading was in range, 28k to 32 k. The tech ohmed out the A and B thermostat wires on the water source heat pump from the upstairs. His ohm reading was not in range of a normal infinity board. His reading was around 64.4k. The tech then made the long walk to the basement where the “geothermal heat pump” was located. Bingo. 

Disclaimer: The technical statements, information and recommendations contained herein are believed to be accurate as of the date hereof, but Mingledorff’s does not make representations or warranties, express or implied, as to its accuracy, its completeness, or the results to be obtained. The information is being provided for informational purposes only and is intended for use by persons having adequate skill and expertise regarding the proper selection, use and application of the products and recommendations and at their own risk and discretion. 

Portrait of a smiling man in a blue polo shirt against a white background

Kevin Thigpen

Technical Services Manager North Alabama District

March 31, 2020

How to Check Fault Codes Stored in Controller

Mingledorff’s Technical Services Group would like to share these steps on how to check faults and HVAC codes to see if you have an “active” fault.



From time to time, our Technical Services Group gets calls where the Service Tech doesn’t know how to check the fault codes stored in the controller. This information is helpful with seeing how the system has been running. The following steps will help your Service Tech see the last 10 events the system has stored.

Thermostat touchscreen with a red arrow pointing to the “menu” button and text “Press Menu”

Step 1

From the main screen push the arrow on bottom right side of screen.

Menu screen with a highlighted car icon and arrows pointing to “Press and hold 10 sec” instruction.

Step 2

You will see a baseball cap. Press and hold for 10 seconds (note the screen will change)

Black menu screen with a red arrow pointing to the down arrow button.

Step 3

You are now in the installation and service screen. Press the arrow on bottom right.

Black menu screen labeled “installation & service” with “service information” highlighted and a red arrow pointing to it.

Step 4

Select the service information.

Black service info menu with a red arrow pointing to “Select Last 10 System Events” and a dark blue “done” button.

Step 5

Select "last 10 system events".

HVAC error log screen showing last 10 system events with heat and AC faults and active status

Step 6

This screen will have the last 10 events. If it's an active fault, the system will not run until the fault is cleared.

By following these steps, you will be able to see the fault history, when the fault occured, and how many times the system has tripped on a fault.

249 VAN Launch Kit 249 VAN Consumer Brochure Smart Thermostat Sell Sheet 249 VAN Launch Kit

Unlock the Full Potential

View Quick Start Guide

This installation was on a 4-story home, and the tech had not yet gone to the basement to troubleshoot the “infinity” water source heat pump, as he was told he by the homeowner. He was in the attic at the infinity furnace above the 4th floor. He was getting his dcv in the proper range on his A and B green plug on the air handler, 3 to 4 vdc. His indoor board ohm reading was in range, 28k to 32 k. The tech ohmed out the A and B thermostat wires on the water source heat pump from the upstairs. His ohm reading was not in range of a normal infinity board. His reading was around 64.4k. The tech then made the long walk to the basement where the “geothermal heat pump” was located. Bingo. 


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