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User Guide | Danfoss troubleshooting guide for supermarket electronics
3. AK-CC 550A
© Danfoss | Climate Solutions | 2022.02
AKV Not Opening
1. Is proper voltage at terminals 5&6 (should match coil voltage spec)?
2. Is case controller calling for valve to be open? (parameter u23 > 0%)
a. If yes
i. If voltage on 5 but not 6, bad relay
ii. If no voltage on 5, check voltage source
iii. If voltage to 5&6 ok, could be bad coil or issue with valve blockage
b. If no
i. Is superheat reading correct? (see 'incorrect superheat' below to troubleshoot)
ii. Is saturated suction temp above MOP temp setting (parameter u26 vs. n11)
iii. Is main switch on (r12)?
iv. Verify 'close EEV during rack shutdown' setting at rack controller is not exceeded
v. Verify shutdown schedule in rack controller not enabled
Incorrect Superheat
1. Is coil outlet sensor (s2) accurate?
a. Check parameter u20. If reading inaccurate, sensor should be replaced as this can lead to
floodback.
2. Is pressure transducer accurate?
a. Check parameter o20 (-15psi)
b. Check parameter o21 (174psi-HFC, 855psi-CO2)
Pe Error (E20)
1. Verify transducer wiring
a. If using 060G1034 connector, terminals 30, 31, 32 wired black, blue, brown.
b. Measure voltage across termainls 30, 31. Should be 5Vdc
c. Measure voltage across terminals 31, 32. Should be in range of 0.5-4.5Vdc.
d. Verify transducer type. Label of transducer should say AKS32R (HFC) or AKS 2050 (CO2)
S3 Error (E25)
1. If no return air (s3) sensor exists, verify the following parameters:
a. R15 = 100%
b. A36 = 100%
c. O17 = 100%
d. R61 = 100%
2. If return air sensor does exist, verify ohm reading of sensor, and confirm wired to terminals 37, 38.
AK-CC 550A Case Controllers Offline
1. Complete rescan
2. Verify if loop is Modbus or Lon
a. If LON, is comm card installed?
b. If Modbus, verify polarity on all units is consistent
3. Verify 'Channel Lonworks' or 'Channel Modbus' enabled appropriately on Network Nodes screen
a. If not, update and rescan afterwards
4. Verify term resistor switch position at AK-SM 800 is correct
a. If 1 loop from plug, switch = 'On' position
b. If 2 loops from plug, switch = 'Off' position
5. Verify EOL resistor in place at end of loop(s)
a. 120 Ω resistor
6. Verify # of devices on system manager is less than 120.
7. Verify total loop distance less than 4000 ft.
a. If longer, repeater must be added.
8. Verify no Duplicates on System Manager
a. Found under Duplicates tab in Network Nodes
b. If duplicates exist, identify controllers sharing address and correct
9. Verify wire type ok
a. Should be EIA485 rated cable
b. Refer to Danfoss comm guidelines document as needed
10. Isolate loop in sections, rescan
a. Identifies where comm problem may be introduced
BC337731384771en-000301 | 6
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