User Guide | Danfoss troubleshooting guide for supermarket electronics
7 | BC337731384771en-000301
© Danfoss | Climate Solutions | 2022.02
Mismatch Error during v2.0 Firmware Install
1. Refer to AK-CC 550A application guide, “Installing AK-CC 550A with the new v2.0 firmware”
https://www.danfoss.com/en-us/service-and-support/fix-and-troubleshooting/supporting-
Configuration (AK-CC 550A to AK-SM 800)
1. Refer to AK-CC 550A service guide, “AK-CC 550A to AK-SM 800 Configuration”
https://www.danfoss.com/en-us/service-and-support/fix-and-troubleshooting/supporting-
Dual Temp Setup
1. Dual temp setup uses the digital input on the case controller (below example uses DI1)
a. Set parameter o02 to 7 for thermostat band changeover (European term for dual temp)
b. Define your secondary setpoint in parameter r21
c. Define high and low alarm settings for that setpoint in parameter A20 and A21
4. AK-CC 750
Replacing AK-CC 750
1. Set address on the case controller
2. Perform rescan on rack controller
3. Do not upload from case controller
4. Verify the main switch is off
5. Determine how many evaporators are controlled by AK-CC 750
6. Set the Quick Setup in Config. Once Quick Setup is completed, download to AK-CC 750
7. Verify the number of evaporators is correct
8. Turn the main switch on
5. AK-XM Modules
AKS Temp Sensor not Reading on IO Module
1. Verify input sensor is wired to, verify program matches (including address and sensor type)
2. Ensure board/point is online
3. If reading 320F in program, this indicates open, -50F indicates short.
4. Ohm out sensor at module
a. If reading an open, break in cable or loose connection between module and probe
b. If reading closed, likely a short in cable between module and probe
c. If reading expected resistance (compare to temp-ohm chart for PT1000), move sensor to
different input and reprogram address
d. Verify other sensors on module reading ok to ensure not a larger problem
i. If so, may need to isolate sensors to identify problematic input on module
5. Verify that no external resistors are still wired to the board-point in question.
AK-XM 103A module not coming online
1. If 255, version must be v2.101 or higher
Relay will not respond to override through program
1. Ensure module has power, online
2. Check Service screen in Rack controller. If ‘remote’, override is through switch at relay module
3. If using the XM-103A module on the same controller, verify that relay points have not been
mistakenly assigned to the same board as the XM-103A.
Sensor Readings Fluctuating
1. Ensure module has steady voltage, ground connected on power plug, shield connected on comm
plug
2. If comm module is not powered by Danfoss power supply, switch to one. Lack of filtering from
other manufacturers or direct from RTU condenser, etc can lead to this.
3. Remove earth ground to see if fluctuations stop. This points to a bad transformer/power supply, or
miswiring.
4. Remove inputs from modules one at a time, checking other readings each time. Feedback from a
set of wires into the modules can cause this issue.
Intermittent IO Offline Issues
1. Ensure end-of-line termination is correct. Physical resistor or switch enabled (not both) at last
module, not enabled anywhere else in comm loop.
2. Ensure no loose comm cabling, strands touching, etc.
3. If issues are on module in condenser, very rare but possible issues from voltage spike requiring
snubbers. Contact Danfoss to discuss further.
