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What This Guide Helps With
Troubleshooting missing, intermittent, or inaccurate CPR compression feedback caused by electrode placement, CPR sensor position, pad connections, surface movement, or accessory failure.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not interrupt clinically indicated CPR to perform extended equipment troubleshooting.
If CPR feedback fails during an active resuscitation:
- Continue chest compressions according to the facility’s resuscitation protocol.
- Do not delay rhythm analysis or defibrillation solely because CPR feedback is unavailable.
- Use trained clinical judgment for compression rate, depth, recoil, and hand placement.
- Obtain another verified AED or monitor/defibrillator when equipment performance is uncertain.
Expected outcome: CPR and defibrillation continue without depending on potentially inaccurate feedback.
Continue Clinical Engineering troubleshooting only after the device has been removed from active patient use.
2. Confirm the Reported Failure
Determine whether the complaint involves:
- No compression-depth bar or visual movement
- No compression-rate feedback
- Missing or delayed “Push Harder” or corrective prompts
- Feedback that appears only intermittently
- Depth readings that do not match the applied compressions
- CPR feedback that stops when the cable or pads are moved
Record whether defibrillation prompts, rhythm analysis, audio prompts, and the display otherwise function normally.
Expected outcome: The failure is isolated to CPR feedback rather than a broader AED malfunction.
3. Verify the Correct Electrodes Are Installed
Confirm that genuine, compatible ZOLL CPR Uni-padz are connected to the AED 3.
The AED 3 uses a sensor incorporated into the CPR electrode assembly to measure compression movement and provide rate-and-depth feedback. Standard electrodes without the required CPR sensor may not provide this function.
Inspect the package and electrodes for:
- Correct product identification
- Expiration date
- Opened or damaged packaging
- Visible cable damage
- Contamination or moisture
- Signs that the pads were previously used
Expected outcome: The correct, unopened, in-date electrode set is available.
If an incorrect, expired, damaged, or previously used set is found, replace it and repeat the functional evaluation. If feedback returns, stop troubleshooting.
4. Inspect the Electrode Connector
Disconnect and reconnect the CPR Uni-padz connector according to normal operating procedures.
Check for:
- Partial insertion
- Debris or moisture
- Bent, recessed, or damaged contacts
- A cracked connector housing
- Cable strain near the connector
- Intermittent operation when the connector is gently handled
Do not probe, bend, or attempt to repair connector contacts.
Expected outcome: The electrode connector is fully seated and remains stable without intermittent feedback.
If reseating restores consistent CPR detection, stop troubleshooting.
5. Verify CPR Sensor and Hand-Placement Position
Using an approved CPR training manikin, position the electrodes and CPR sensor exactly as shown on the electrode illustrations.
The rescuer’s hands must apply compressions over the marked hand-placement indicator containing the sensor. The sensor detects compression movement and sends the information to the AED for processing.
Check that:
- The sensor is centered over the intended compression location.
- Compressions are applied directly over the marked indicator.
- The sensor is not folded, twisted, displaced, or trapped beneath another item.
- The electrode cable is not pulling the sensor away from the compression area.
Expected outcome: Compression activity produces a responsive depth display and appropriate feedback prompts.
If correcting sensor position restores feedback, stop troubleshooting.
6. Confirm Proper Pad Adhesion
Verify that the electrodes and CPR sensor assembly lie flat against the manikin surface.
Look for:
- Lifted edges
- Air pockets
- Wrinkled adhesive
- Contamination on the contact surface
- Excessive cable tension
- Poor contact caused by an uneven or inappropriate test surface
Do not reuse clinical electrodes after opening them solely for repeated troubleshooting unless permitted by facility policy and manufacturer instructions.
Expected outcome: The electrode assembly remains securely positioned throughout compressions.
If poor adhesion is present, test with an approved replacement set. If feedback becomes reliable, document the original electrodes as the cause and stop.
7. Evaluate the Test Surface and Manikin
Test CPR feedback only on an appropriate CPR manikin or manufacturer-approved test setup.
A soft mattress, unstable stretcher, moving surface, rigid tabletop without chest travel, or unsuitable simulator can produce misleading compression-depth results because the sensor measures movement during compressions.
Place the manikin on a stable surface and ensure it provides realistic chest displacement.
Expected outcome: Compression feedback changes consistently as compression depth and rate are varied.
If the AED responds correctly on an appropriate setup, the device is functioning as expected and the original test method or surface likely caused the complaint.
8. Verify Adult or Child Mode
Confirm that the selected patient mode matches the intended functional test.
The AED 3 uses CPR Uni-padz for adult and child rescue, with pad repositioning and selection of the appropriate operating mode.
Check that:
- Adult mode is selected for an adult CPR test.
- Child mode is selected only when evaluating the pediatric configuration.
- The pads are arranged according to the illustrations for the selected mode.
- The reported issue is not simply a difference in the displayed feedback behavior between modes.
Expected outcome: The displayed mode and electrode placement match the test configuration.
If correcting the mode or pad arrangement restores expected feedback, stop troubleshooting.
9. Check Audio and Display Operation
Observe the AED during a simulated rescue sequence.
Confirm whether:
- The compression-depth bar is visible.
- The CPR timer advances.
- The metronome or CPR prompts are audible.
- Corrective prompts occur when compression depth or rate is intentionally varied.
- The screen remains responsive and readable.
- Audio volume is adequate.
The AED 3 provides visual compression-depth information and real-time CPR guidance through its Real CPR Help technology.
Expected outcome: Both visual and audible CPR guidance respond appropriately.
If visual feedback works but audio does not, troubleshoot the issue as an alarm-speaker or voice-prompt failure rather than a compression-detection failure.
10. Test With a Known-Good Electrode Set
When available, connect a compatible, in-date electrode set known to function correctly.
Repeat the test using:
- The same AED
- The same approved manikin
- The same surface
- Consistent pad positioning
- Comparable compression technique
Expected outcome: The known-good electrodes provide stable rate-and-depth feedback.
Interpretation:
- If the known-good set works, remove the original electrode set from service.
- If both sets fail in the same manner, suspect an AED connector, signal-processing, software, display, or internal hardware problem.
Do not repeatedly open new clinical electrode packages unless the test is necessary and authorized.
11. Restart and Review Readiness Status
Disconnect the test electrodes, power the AED off, wait briefly, and restart it according to normal operating procedures.
Observe:
- Startup behavior
- Readiness indicator
- Error messages
- Audible alerts
- Battery condition
- Whether the electrode connection is recognized
- Whether the problem returns during a controlled retest
Expected outcome: The AED starts normally, indicates readiness, recognizes the electrodes, and provides consistent CPR feedback.
If a readiness failure, service message, or diagnostic code appears, record it exactly and discontinue field troubleshooting.
12. Compare the Complaint With Stored Event Information
When authorized and available, review the applicable rescue or test record using the facility’s approved ZOLL data-management process.
Event information may help determine whether compression activity was recorded even though the rescuer reported that feedback was not displayed or heard. ZOLL identifies CPR rate and compression-depth information as part of AED rescue-event reporting capabilities.
Expected outcome: The record helps distinguish among:
- No compression signal received
- Compression data recorded but not displayed
- Audio feedback failure
- Intermittent electrode or connector operation
- Incorrect user or test setup
Do not alter configuration settings or software unless authorized by the facility and supported by current ZOLL service documentation.
If the Problem Persists
If compatible electrodes, connector seating, sensor placement, adhesion, patient mode, test surface, audio, display operation, and a known-good electrode set have been verified, common external causes have been ruled out.
The failure may involve the electrode receptacle, CPR sensor input circuit, internal signal processing, display system, software, or another internal component.
The AED should be:
- Removed from service
- Labeled Out of Service
- Replaced with a verified AED
- Sent for authorized repair or bench evaluation
- Evaluated using current ZOLL service procedures and approved test equipment
Do not open the AED or perform internal board-level repairs without appropriate authorization, training, and manufacturer service documentation.
Knowing when to stop external troubleshooting and escalate the device is proper troubleshooting.
Clinical Use Tip
CPR feedback is an aid and must not become a reason to interrupt chest compressions. During an active emergency, continue trained CPR and obtain another verified defibrillator if the AED’s overall performance is uncertain.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the ZOLL AED 3 displayed no compression-depth feedback and did not provide corrective CPR prompts during a readiness drill."
Cause
What was observed during troubleshooting.
Example:
"Testing found that the CPR Uni-padz sensor was displaced from the marked compression location and did not remain flat against the manikin."
Resolution
What action was taken.
Example:
"Repositioned the electrode assembly on an approved CPR manikin, repeated the simulated rescue sequence, and verified stable compression-depth, rate, timer, visual, and audio feedback."
Helpful Details to Include (If Known)
- AED readiness indicator condition
- Exact error or service message
- CPR Uni-padz product and expiration information
- Electrode package condition
- Electrode connector inspected and reseated
- Known-good electrodes tested
- Adult or child mode selected
- CPR sensor position
- Manikin and test surface used
- Compression-depth bar behavior
- Metronome and voice-prompt behavior
- Battery condition
- Intermittent response when the cable was moved
- Event data reviewed
- Final device status
- Replacement AED provided
- Repair or vendor case number
Final Thought
CPR-feedback troubleshooting should begin with patient safety, compatible electrodes, sensor placement, secure connections, and a controlled test setup. When external causes have been eliminated, remove the AED from service and escalate it for authorized evaluation. Clear CCR documentation preserves both device history and confidence in emergency-equipment readiness.
That is successful troubleshooting.