(h)  
Remove the cooling source from the low temperature switch.

 (i)  
Apply a heating source to the low temperature switch or let the temperature in the compartment increase to more than 50°F (10°C).

 NOTE: Make sure you do not increase the temperature of the
____ overheat switch to more than 90°F (32°C) (if it is necessary, apply a cooling source to the overheat switch).
 (j)  Make sure the control valve closes and the override valve stays open.
 S 735-059
 (2)  Do a test of the overheat switch:
 (a)  
Make sure the AFT CARGO HT switch on the P5 overhead panel is set to ON.

 (b)  
Set the applicable CARGO HEAT switch (forward of the cargo compartment door) to the up (50 degrees F/10 degrees C) position.

 (c)  
Apply a heating source to the high temperature switch to close the control valve.

 (d)  
Make sure the applicable control valve is closed.

 (e)  
Apply a heating source to the overheat switch to increase the temperature of the switch to more than 90°F (32°C).

 (f)  
Make sure the override valve is closed.

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 (g)  
Make sure the TEMP light on the AFT CARGO HT switch is off.

 (h)  
Make sure the advisory message TEMP CARGO HEAT does not show on the EICAS display.

 (i)  
Apply a cooling source to the high temperature switch to open the control valve while you maintain the overheat switch temperature above 90°F (32°C).

 (j)  
Make sure the applicable control valve opens.

 (k)  
Make sure the TEMP light on the AFT CARGO HT switch comes on.

 (l)  
Make sure the advisory message TEMP CARGO HEAT shows on the EICAS display.

 (m)  
Apply a cooling source to the overheat switch to decrease the temperature of the switch to less than 80°F (27°C).

 (n)  
Make sure the override valve opens.

 (o)  
Make sure the TEMP light on the AFT CARGO HT switch goes out.

 (p)  
Make sure the advisory message TEMP CARGO HEAT does not show on the EICAS display.

 S 735-019
 (3)  Do a test of the high temperature switch:
 (a)  
Set the AFT CARGO HT switch on the P5 overhead panel to off.

 (b)  
Make sure the ON light on the AFT CARGO HT switch goes out.

 (c)  
Make sure the override valve and the control valve are closed.

 (d)  
Make sure the CARGO HEAT switch is set to 50 degrees F (10 degrees C).

 (e)  
If the temperature in the compartment is more than 50 degrees F (10 degrees C), apply a cooling source to the high temperature switch to decrease the temperature of the switch to less than 50 degrees F (10 degrees C).

 (f)  
If the temperature in the compartment is more than 90°F (32°C), apply a cooling source to the overheat switch.

 (g)  
Set the AFT CARGO HEAT switch to ON.

 (h)  
Make sure the override valve and the control valve are open.

 (i)  
Remove the cooling source from the high temperature switch.

 (j)  
Apply a heating source to the high temperature switch or let the temperature in the compartment increase to more than 60 degrees F (16 degrees C).

 NOTE: Make sure you do not increase the temperature of the
____ overheat switch to more than 90 degrees F (32 degrees C) (if it is necessary, apply a cooling source to the overheat switch).
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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747-400
MAINTENANCE MANUAL

 (k)  
Make sure the control valve closes and the override valve stays open.

 (l)  
　
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