On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
Troubleshooting thermostat-open or over-temperature alarms involving airflow obstruction, blocked intake, hose restriction, filter condition, or internal temperature-control failure.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Immediately discontinue use of the WarmTouch WT 6000 if a thermostat-open or over-temperature alarm occurs during patient warming.
Move the patient to another approved warming system or alternate warming method according to clinical procedure before troubleshooting.
Expected outcome: The patient is no longer dependent on a warming unit with an unresolved heat-control alarm.
Why it matters: The WT 6000 monitors delivered air temperature and shuts down the heater and fan when temperature exceeds its operating limit; the safety thermostat provides additional over-temperature protection.
2. Verify and Document the Alarm Condition
With the unit removed from clinical use, confirm the displayed alarm or error message.
Document:
- Exact alarm text or error code.
- Temperature setting in use when the alarm occurred.
- Whether the unit was operating in Boost, High, Medium, Low, or Ambient mode.
- Whether the heater and fan stopped.
- Whether the alarm clears after the unit cools and is restarted.
If the display reports Error Code 157, the service manual identifies this as Thermostat open.
Expected outcome: The reported condition is accurately captured for troubleshooting and repair follow-up.
3. Inspect for Signs of Excessive Heat or Damage
Unplug the warming unit and allow it to cool before inspecting it.
Check the exterior, power cord, hose, nozzle, and blanket connection area for:
- Unusual heat.
- Burnt odor.
- Melted, discolored, or damaged plastic.
- Cracked or crushed hose sections.
- Evidence of fluid intrusion.
Expected outcome: No evidence of unsafe overheating or physical damage is present.
If heat damage, burning odor, or melted components are found: Stop troubleshooting, label the unit Out of Service, and send it for repair evaluation.
4. Verify the Power Source and Operating Environment
Confirm the unit is connected to a suitable hospital-grade grounded outlet.
Verify that the unit was not being operated:
- In an unusually hot environment.
- Directly next to a heat source.
- With the housing obstructed by linens, drapes, equipment, or stored supplies.
- In a stacked or confined arrangement that could restrict airflow.
Expected outcome: The unit has a proper power source and adequate clearance for normal air movement.
5. Check the Air Intake and External Vent Areas
Inspect the visible air intake and vent areas for lint, dust buildup, packaging material, linens, drapes, or other obstructions.
Do not open the enclosure or bypass safety devices.
Remove only external obstructions that can be safely cleared without disassembly.
Expected outcome: External air intake and vent areas are unobstructed.
Why it matters: Restricted airflow can contribute to abnormal temperature conditions in convective warming systems.
6. Inspect the Hose and Nozzle
Examine the warming hose from the unit to the nozzle.
Confirm that the hose is:
- Fully extended enough for normal airflow.
- Not sharply kinked, crushed, collapsed, or pinched under equipment.
- Free of visible internal blockage at the nozzle.
- Properly attached and undamaged.
Expected outcome: The hose and nozzle provide an unobstructed path for airflow.
If a damaged or obstructed hose is found: Remove the affected accessory from use and retest only with an approved, intact component when permitted by facility procedure.
7. Verify the Correct Blanket and Connection
Confirm that an approved WarmTouch blanket was being used and that the nozzle was properly secured to the blanket inlet.
Do not operate the warming unit with the hose blowing directly toward the patient or without the nozzle connected to the warming blanket.
Expected outcome: Correct blanket use and proper nozzle attachment are confirmed.
Why it matters: The manufacturer specifies use with WarmTouch blankets and warns against free-hosing because thermal injury may occur.
8. Review Filter Status and Exterior Filter Condition
Check for an onscreen filter expiration warning or documented overdue filter maintenance.
Inspect only the externally accessible condition of the filter enclosure area for obvious blockage, heavy lint accumulation, or damage.
Expected outcome: No external indication of overdue or restricted filter condition is present.
If the filter is overdue, visibly restricted, or the unit indicates filter service is required: Remove the unit from service for maintenance according to the approved service process.
9. Perform a Controlled Functional Check Only If Safe
Only after the unit has cooled, external obstructions have been ruled out, and no physical damage is present, perform a brief functional check off-patient according to department procedure.
Use an approved blanket connection. Observe for:
- Normal startup.
- Normal airflow.
- Recurrence of the alarm.
- Heater or fan shutdown.
- Unusual odor, noise, or excessive heat.
Expected outcome: The unit operates without recurrence of the thermostat-open or over-temperature alarm.
If the alarm returns: Stop testing. The unit is not safe for clinical use and requires repair evaluation.
10. Escalate Error Code 157 or Recurring Over-Temperature Conditions
If Error Code 157 — Thermostat open is present, or the over-temperature alarm repeats after external airflow, hose, blanket, filter, and environmental checks are completed, do not continue clinical use.
The WT 6000 service manual identifies Error Code 157 troubleshooting as evaluation of the internal thermistor position and, if required, replacement of the power PCBA. These are repair-level actions beyond basic external troubleshooting.
Expected outcome: A suspected internal temperature-sensing or heater-control fault is appropriately escalated.
If the Problem Persists
If the thermostat-open or over-temperature alarm remains after safe external checks, common external causes have been ruled out and the problem is likely internal to the temperature-sensing, thermostat, heater-control, or power-control system.
The device should be:
- Removed from service.
- Labeled Out of Service.
- Sent for repair or bench evaluation by qualified service personnel.
Knowing when to stop is proper troubleshooting. A warming unit with an unresolved temperature-control alarm should not be returned to patient care based only on a temporary alarm reset.
Clinical Use Tip
Never troubleshoot an over-temperature or thermostat-open condition while the device is actively warming a patient. Move the patient to a known-working warming system first, then evaluate the affected unit in a controlled off-patient setting.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the Medtronic WarmTouch WT 6000 alarmed for thermostat open/over-temperature during patient warming and stopped delivering warmed airflow."
Cause
What was observed during troubleshooting.
Example:
"Verified recurring thermostat-open alarm after confirming the hose, blanket connection, visible air intake, and operating environment were unobstructed, indicating a likely internal temperature-control fault."
Resolution
What action was taken.
Example:
"Removed the WarmTouch WT 6000 from service, applied an Out of Service label, documented the displayed alarm condition, and routed the unit for bench evaluation and repair."
Helpful Details to Include (If Known)
- Exact displayed alarm text or error code, including Error Code 157 if present.
- Temperature mode active when the alarm occurred.
- Whether the unit had been operating in Boost mode.
- Outlet tested and power cord condition.
- Hose and nozzle condition.
- Blanket type and attachment status.
- Air intake or vent obstruction observed.
- Filter warning or maintenance status.
- Unusual heat, odor, sound, or visible damage.
- Whether the alarm recurred during off-patient functional check.
- Final device status.
Final Thought
A thermostat-open or over-temperature alarm involves the safety of delivered warming therapy. Begin with patient protection, rule out simple external airflow and accessory issues, and escalate promptly when the alarm repeats or indicates an internal fault. Accurate CCR documentation supports safe repair decisions and prevents an unreliable device from returning to use.
That is successful troubleshooting.