It is a good practice to make sure all of your dip switches are set to the factory position on all of your flow selector boxes during installation. If the dip switches are not set in the factory position you will have L11 and E17 error codes to follow. You can verify the factory dip switch settings by looking at access door on the flow selector box. The L11 and E17 error codes can also be caused by wiring issues, good wiring practices can prevent having problems.


Changing dip switches on your flow selectors is not necessary because all of your flow selector addresses and port numbers are set using and codes 00FE and 0105 on your thermostat. Making sure your flow selector address and your flow selector port address is correct will make the start up process much easier. If care is taken and you have a good understanding of the wiring and installation of a VRF system the start up process can be close to seamless.


L11- Detected indoor unit address, Flow selector unit not connected.


E17- Communication trouble between indoor unit and flow selector unit.

Andy Johnson

VRF Tech Support and Quality Assurance • North Georgia, North Alabama

September 17, 2024

The Sleeping Carrier/Bryant VRF

This month we will be covering a scenario that baffled even the Mingledorff’s VRF group for a while. Hard to believe right?


Scenario: You arrive at a jobsite with a Carrier VRF unit not cooling. Looking at all the components of the system, there aren’t any errors. Maybe something is going on with the Outdoor Unit (ODU). Looking at the spot check and main boards and they both display a _0_0.


Only if it is the filter board for the #1 compressor the unit will have a blank display.

Close-up of a green electronic circuit board with two red LED displays and various components.

Remembering what you learned in class, this is telling you the compressors are both at 0 RPS or OFF. Time to get out the computer with STT. First thing you notice is the ODU grayed out like it’s in standby mode. “That’s weird, I know all the thermostats are set to 70 and it’s 76 degrees in the space.”

Red-outlined ODU panel showing a white equipment header and status readouts.

Given this very ODD scenario we need to know a little information beforehand. Every compressor and fan motor have their own inverter boards. The location of the inverter boards depends on the quantity of compressors.


Compressor 1: Left side of ODU in the main control panel behind the main board.


Compressor 2: Right side of ODU in the panel shown below.


Compressor 3: Will be the panel that is the furthest right side of the unit.

Open HVAC unit with red arrow pointing to inverter board inside, carrier panel open

Today we will be focusing on the 2nd compressor inverter board. After removing the access panel for Compressor 2 you will see the Fuse/AC filter board. The compressor board lies behind the hinged door. LEDs can be accessed by the viewing window on the top right.

Open electrical cabinet with circuit board, highlighted by a red arrow on the right side.

RED LED: Power to board


GREEN LED: Status/Error



If there is an error on the green LED for the Compressor 2 Inverter board use the chart below to give you an idea where to start:

Crop rotation table with crop groups and recommended intervals on a white spreadsheet-like layout.

The error more than likely will be an L0 or L7 code indicating either a bad inverter board for the compressor OR fuse board.

Green circuit board with two large copper coils and multiple electronic components mounted inside a device

So where do we start? The easiest and fastest thing to check is the fuses. We need to ensure these non-replaceable fuses are intact. This can be accomplished 1 of 2 ways.


Power on: Check VAC voltage on either side of the fuse. If you get a voltage reading the fuse is bad. If the fuse is good, you should get a 0 VAC reading.


Power Off: Wait at least 3-5 minutes for capacitors to discharge and check continuity across the fuse.


!!WARNING!!


WHEN WORKING ON LIVE EQUIPMENT FOLLOW ALL SAFETY MEASURES. MINGLEDORFF’S IS NOT RESPONSIBLE FOR INJURY OR DAMAGE.

Hand holding test probes near a green circuit board with copper coils and wires inside electronics equipment

If any of the fuses are blown the board needs replaced. Contact your TM to order.


If you have any questions please feel free to contact the Mingledorff’s Technical Service Team.

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.

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