Projector Reset How do I reset the projector after I clean the Air Filter? The message of ,Clean air filter keeps coming up.

follow this steps and fix it. God bless you

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  Secure the lamp cover and the air filter cover of the projector body if the projector does not power on. Ensure that the power cable is firmly connected to the projector and an active power plug. If the projector was turned off and then on quickly--let it sit for 90 seconds before trying to turn it on.
  
  
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  Replace the projection lamp if the projector will not power on or if the lamp indicator is flashing. Turn off the projector and let it sit for at least 30 minutes. Locate the lamp cover and remove or loosen the lamp cover with a screwdriver. Carefully remove the projection lamp from the projector housing using the handle, if available.
  
  
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  Place the new projection lamp into the projector housing and secure it to the projector. Replace the lamp cover and reset the lamp timer. Power on the projector to ensure the new lamp is working correctly.
  
  
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  Remove the projector from the enclosed area to allow air circulation if it constantly overheats. Place the projector into an open area and make sure there is no blockage for the ventilation holes. Unplug the projector for at least 45 minutes to allow it to soft reset.
  
  
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  Clean the air filter to allow the projector better air circulation. Turn off the projector and unplug it from the outlet. Remove the air filter cover and use a vacuum to remove dust from the area. If the filter is unable to be cleaned correctly or is damaged, then replace it. Pull the air filter from the projector and place the new one in the now empty slot. Close and secure the air filter cover.
  
  

Air-Filter
Cleaning the Air Filter
The air filter should be cleaned as described below at intervals of approximately 100 hours. When
the filter is used for approximately 100 hours, the message "CLEAN THE AIR FILTER" appears
when the projector is switched on.
1 Switch the projector power supply OFF, and remove the power cord from the power outlet.
2 Clean the air filter with a vacuum cleaner.
3 Reset the Filter Timer using the function of the FILTER TIME on the OPTION Menu. Please
refer to the description of the "FILTER TIME" on the Table 9: MAIN Menu.
Replacing the Air Filter
Replace the air filter if contamination cannot be removed, or if it is damaged. To order a new air
filter see page 26 for contact information.
1 Switch the projector power OFF, and remove the power cord from the power outlet.
2 Remove the filter cover and the filter.
3 Replace the new air-filter and the filter cover.
4 Reset the Filter Timer using the function of the FILTER TIME on the OPTION Menu. Refer to
the description of the "FILTER TIME" on Table 9: MAIN Menu.

Procedure for resetting filter time.
Pressing the RESET button for about 3 seconds displays the FILTER TIME menu. Select the RESET using button to reset the timer. : RESET <- CANCEL Selecting the RESET resets the count of the lamp timer to 0. memo Perform this function only when you have cleaned or replaced the air filter. The filter timer counts the used time of the air filter after cleaning or replacement, to display the messages about the air filter. Incorrect performing causes incorrect operation of the messages. memo About caring for the air filter, please refer to the section "Air Filter".
Users manual located here. http://www.aboutprojectors.com/pdf/hitachi-cp-x1250-manual.pdf
Good info deserves a good thumbs up! Thank you!

WARNING ?Before caring, make sure the power switch is off and the
power cable is not plugged in, then allow the projector to cool sufficiently. The
care in a high temperature state of the projector could cause a burn and/or
malfunction to the projector.
?Use only the air filter of the specified type. Do not use the projector with the
air filter and filter cover removed.
?Avoid wetting the projector or inserting liquids in the projector. It could result
in a fire, an electric shock, and and/or malfunction to the projector.
CAUTION ?Please replace the air filter when it is damaged or too soiled,
and also when you replace the lamp.When the indicators or a message prompts you to clean the air filter, clean the air filter as soon as possible. If the air filter becomes clogged by dust or the like, internal temperatures rise and the power may be automatically turned off for malfunction prevention.
1. Turn the projector off, and unplug the power cord. Allow the projector to cool for at least 45 minutes and prepare a vacuum cleaner.
2. After making sure that the projector is cool adequately, slowly turn the projector so that the lens-side is facing up. Please be careful for a projector not to fall. While the projector is placed lens-side up, hold the projector.
3. Putting a finger on the filter cover's knob, slide the filter cover in the direction of the arrow to remove it.
4. Holding the air filter's knob, pull the air filter off.
5. Apply a vacuum cleaner to the vent of the projector for the air filter. And then slowly turn the projector bottom up.
6. Apply a vacuum cleaner to the air filter and filter cover.
Please replace the air filter when it is damaged or too soiled.
To prepare a new air filter, contact your dealer and tell the air filter type number = NJ09702.
An air filter of specified type will come even with the replacement lamp for this projector.
7. Position the cleaned air filter or a new air filter into place, and push the points
of "PUSH" word with claws to fix the air filter.
8. Replace the filter cover and snap it back into place.
9. Slowly turn the projector so that the top is facing up.
10. Turn the projector on, and reset the filter time using the FILTER TIME
function of OPTION menu (?37).
NOTE • Incorrectly resetting of the filter timer (resetting without replacement,
or neglect of resetting after replacement) will result in incorrect message
functions.

Hi There Teacher!
the air filter unclips on the left hand side, lens facing out.
after vacumming out the filter see below for filter reset counter procedure
Good Luck!
Turn the projector on and reset the filter time using the FILTER TIME item in the EASY MENU. Before taking care of the air filter, make sure the power switch is off and the power cable is not plugged in, then allow the projector to cool sufficiently. Taking care of the air filter in a high temperature state of the projector could cause an electric shock, a burn or malfunction to the projector. Use only the air filter of the specified type. Do not use the projector without the air filter or the filter cover. It could result in a fire or malfunction to the projector. Clean the air filter periodically. If the air filter becomes clogged by dust or the like, internal temperatures rise and could cause a fire, a burn or malfunction to the projector. WARNING Please replace the air filter when it is damaged or too soiled. When you replace the projection lamp, please replace the air filter . An air filter of specified type will come together with a replacement lamp for this projector . Please reset the filter time only when you have cleaned or replaced the air filter, for a suitable indication about the air filter. The projector may display the message such as ?gCHECK THE AIR FLOW?h or turn off the projector, to prevent the internal heat level rising. NOTE (1) Press the MENU button to display a menu. (2) Point at the FILTER TIME using the ??/?? button, then press the button. A dialog will appear. (3) Press the ?? button to select RESET on the dialog. It performs resetting the filter time.

check in the menu to see if there is a filter timer that you can reset. if so, reset it. if not, there is an air flow sensor on the projector that will send that message if the air flow is decreased so the projector does not overheat. find the filter and remove it. blow it out with canned air and blow out the projector as well. replace the filter and enjoy!

Hi there...FIRST remove the dust filter and clean it with some compressed air, or you can leave it in place and use a vacuum cleaner hose to suction off the dust. Some projectors have a sensor that gets reset when the filter is removed. A lot don't. Check the onscreen menu for a reset option for the dust filter. This option may be only accessible with the remote control...DON'T reset the lamp hours! The most important thing with LCD projectors or any other projector, for that matter, is to keep the dust filters clean--think of someone putting their hand over your nose and mouth. The projectors emit a *huge* amount of heat and need plenty of air flow to remain cool. Also, the benefit of cool air keeps the delicate LCD panels from aging prematurely!---Rick

go into the menu. it should be in the same menu as the lamp timer. as for cleaning the filter, use canned air.

There is a menu item which has both the lamp hour reset and check air flow, etc. You must go into the menu and reset the air flow item. MAKE SURE YOU CLEAN THE DUST FILTER!! Heat is the number one killer of projectors and Hitachi's run "hot". I clean my projector once a week--Hey, I'm not rich. lol! Also, excessive heat will cause the lcd panels to fail prematurely and cause lots of other components to do the same.--Rick

On the right side of the projector there are vents, put a vacume cleaner up to the vents, and the filter will be cleaned.
then on the top of the projector click the down arrow, then go down to option, use the down arrow to highlight the filter time, then hold the reset button on top of the projector for about three seconds. Clean the air filter every 100 hours.