8
3M™ Bair Hugger™ Warming Unit Model 775 – Service Manual
Testing the Over‑Temperature DetectionSystem
!
Warning: Do not perform the over-temperature detection system test
while the warming unit is being used for warming therapy.
!
Caution: Perform all temperature testing of the warming unit with a
3M Model 22110temperature testunit.
!
Caution: Connect each warming unit being tested to a separate
powersource.
SERVICEFREQUENCY
Every 6 months or 500hours of use, or whenever service isperformed.
TOOLS/EQUIPMENT
Model 22110 temperature testunit
Calibrated thermocouple temperature monitor
Method
Note: If continuing from the previous section (Calibrating the Operating
Temperature) skip to step 4.
Note: If the warming unit has been stored at a temperature lower than
20°C, allow it to reach ambient temperature before beginning thetest.
1. Connect the warming unit to a grounded power source. The
warming unit performs a self-test and automatically proceeds to
Standby mode.
2. Connect the temperature test kit to the hose of the warming unit.
3. Press the Ambient button and allow the warming unit to run for
5 minutes.
NOTE: Verify warming unit is set to the high fan (
) setting by ensuring
the indicator light by the upper fan is illuminated.
4. With the warming unit in Ambient mode, press the Alternative Mode
button (See Figure 2. Location of Alternative Mode button on page 7)
and the 43°C button simultaneously for 3 seconds. The warming unit
is now in the Over‑Temperature Detection Test mode. In this mode, the
warming unit performs the following tasks:
• Blower remains ON.
• Heater elements turn ON at fullpower.
• 43°C indicator light flashes.
• Over-temperature timer activates.
• OT Test flashes in the alphanumeric display.
5. Wait for the warming unit to perform the over-temperature test. When
the test is complete, the warming unit performs the following tasks:
• Heater elements turnOFF.
• Blower continues to operate. (NOTE: The blower turns off if an
over-temperature condition occurs during normaluse.)
6. View the alphanumeric display to determine testoutcome:
a. PASS–The warming unit detected an over-temperature
condition within 150seconds. An alarm sounds for 2 short
beeps. The text “PASS” flashes in the alphanumeric display,
followed by thesemessages:
i. OT Test ‑ PASS‑Prx or OT Test ‑PASS‑Dst
ii. TestTime ‑ XXSecs
iii. Unplug ‑ ToReset
b. FAIL–Warming unit did not detect an over-temperature
condition within 150 seconds (time-out failure). An alarm sounds
and the Fault indicator light flashes. The text FAIL flashes in the
alphanumeric display, followed by thesemessages:
i. OT Test ‑FAIL
ii. TestTime ‑ 150Secs
iii. Unplug ‑ ToReset
Note: Do not place a warming unit back into service if it fails the
over-temperature test. Contact 3M technicalsupport.
7. Record the maximum temperature displayed by the test kit.
(Use Maintenance Log on page 17.) If the temperature is outside
the range of 46°C to 56°C, contact 3M technical support for
furtherinstructions.
8. After the test is complete, allow the warming unit to cool by running it
for at least five minutes.
9. Unplug the warming unit to reset it to normaloperation.
Viewing the Fault CodeLog
SERVICEFREQUENCY
As often as necessary.
TOOLS/EQUIPMENT
Nonerequired.
METHOD
1. If your warming unit is already ON, you can access the fault code
log from any operating mode. Otherwise, connect the warming unit
to a grounded power source. The warming unit performs a self-test
and automatically proceeds to Standby mode. Then select any
operatingmode.
2. Press the Alternative Mode button (Figure 2. Location of Alternative
Mode button on page 7) and the 32°C button simultaneously for three
seconds. The warming unit is now in Fault Code Log mode. In this
mode, the warming unit performs the followingtasks:
a. Continues to operate in current operatingmode.
b. 32°C and 38°C indicator lightflashes.
c. Text FC(n) XXX appears in the alphanumeric display. FC is
an abbreviation for the phrase fault code n represents the
numerical order of the fault code in the log, and XXX represents
the code for the fault condition. See page 9for a list of fault
codes and their meanings.
d. The time (HH:MM:SS) of each fault appears below FC(n) XXX
in the alphanumeric display. If the warming unit reaches 100or
more hours the time only reads hours and minutes.
3. Press either the 32°C or 38°C button to view the next fault code in
the log. The warming unit stores a maximum of 5fault codes in non
volatilememory.
4. Press the Alternative Mode button to return the warming unit to its
previous operatingmode.
Clearing the Fault CodeLog
Put the warming unit in Fault Code mode by pressing the Alternative Mode
button and the 32°C button simultaneously for three seconds; then, press
the 43°Cbutton.
NOTE: The fault code log should not be cleared unless instructed to do so
by a 3M representative.
9
GB / 34-8718-8817-7
Fault Code Table
The software will detect and report the following conditions by displaying
the corresponding fault code:
FAULT CONDITION FAULT CODE
Internal sensor 1 over-temperature condition 001
Hose end sensor 2 over-temperature condition 002
Hose end sensor 3 over-temperature condition 003
Internal sensor 1 shorted 004
Hose end sensor 2 shorted 005
Hose end sensor 3 shorted 006
Hose end sensor 2open 007
Rapid button press, blower failure,
open thermostat or low wattage heater failure
008
Open thermostat/medium wattage heater failure 009
High wattage heater failure 010
A/D converter timeout 011
A/D startup check failed 012
(Reserved Fault Code) 013
Error in execution loop 014
Timeout on alphanumeric display busy flag clearing 015
RAM corruption in duplicate RAM locations 016
Error in executing a depressed key 017
Stuck key during startup 050
EEPROM is at max # write cycles 051
Non-0EEPROM byte detected after zeroing 052
EEPROM checksum failure on copy#1
(see page 11)
053
EEPROM compare failure copy #1 to copy #2 054
EEPROM compare failure copy #1 to RAM 055
EEPROM write cycle time out 056
SPI byte transfer time out 057
EEPROM write error when entering standby 059
Real time clock failure 060
Temperature out of range high 070
Temperature out of range low 071
5 V power supply in excess of 5.333V 100
5V power supply under 4.667 V 101
Startup test EEPROM error 102
Startup test RAM error 103
Viewing the Hour Meter
SERVICEFREQUENCY
As often as necessary.
TOOLS/EQUIPMENT
Nonerequired.
METHOD
1. If your warming unit is already ON, you can begin the test from
any operating mode. Otherwise, connect the warming unit to a
grounded power source. The warming unit performs a self-test
and automatically proceeds to Standby mode. Then select any
operatingmode.
2. Press the Alternative Mode button for 3seconds. (See Figure 2.
Location of Alternative Mode button on page 7.) The warming unit
is now in Hour Meter Display mode. In this mode, the warming unit
performs the followingtasks:
a. Continues to operate in current operatingmode.
b. Hours appears in the alphanumeric display.
c. Cumulative hours of warming unit operation appear in the
alphanumeric display. The time is displayed in whole hours only.
3. Wait 60seconds or press the Alternative Mode button to return the
warming unit to its previous operatingmode.
Viewing the OperatingTimer
To view the amount of time the warming unit has been operating in the
current temperature mode, press and hold the current temperature mode
button for at least 3 seconds. The time is displayed in HH:MM:SSformat.
Replacing the AirFilter
SERVICEFREQUENCY
Every 12 months or 500hours of use.
TOOLS/EQUIPMENT
Replacement airfilter
#2Phillipsscrewdriver
!
Caution: Do not attempt to clean the air filter as it may be
contaminated from use. Discard the filter in a manner consistent with
institutional protocol.
Method
1. Disconnect the warming unit from the grounded powersource.
2. Turn the warming unit upside down.
3. Remove the 2 screws located in the louvered filter cover.
4. Lift the filter cover off the warmingunit.
5. Remove the air filter and discard it.
6. Place the new filter in the filter compartment with the gasket toward
the filter ledge.
7. Replace the filter cover with the louvers facing the back of the
warmingunit.
8. Replace the 2 screws in the filtercover.
Replacing theHose
SERVICEFREQUENCY
As needed.
TOOLS/EQUIPMENT
Replacement hose
Needle-nosepliers
Strapwrench
METHOD
Detaching Warming Unit Hose
1. Disconnect the warming unit from the power source before
replacinghose.
2. Unscrew the hosecollar.
3. Slide the hose out of the warming unit. The hose will still be attached
to the warming unit by a cable.
4. By hand or using a needle-nose pliers, carefully detach the cable
connector from the header plug located inside the hose connector
(see Figure 3. Hosereplacement).