WARMING UP Message Appears Between Pages of a Single Print Job

The control panel message, WARMING UP, appears on the HP Color LaserJet 8500 or 8550 series printer's control panel in between pages during a single print job. This issue is most often seen when printing from Tray 1 using tabloid sized (11" x 17") paper. However it can occur using any size media. This message is displayed to indicate that the fuser is changing temperature. This temperature change can be warming up or cooling down. The same message is displayed for both conditions.

The WARMING UP message displayed on the printer control panel is normal and indicates an adjustment in progress of the fuser temperature. This is done to ensure proper fusing as appropriate for the current media type or print mode (color or monochrome). When printing from Tray 1, the fuser temperature is adjusted to a preset baseline temperature between each print job. This is done to ensure that the fuser is not damaged and that high print quality is maintained even when media type is not known in Tray 1. The duration of the warming up message is variable depending on the extent of fuser temperature change needed for the current printing conditions.

The conditions where warming up is displayed between jobs can be triggered by printing from Tray 1 or by changing between monochrome and color pages. In both cases the fuser temperature may be adjusted to ensure the best possible print quality with a wide variety of media for color and monochrome printing. The two scenarios during which this can happen are as follows:

When printing from Tray 1, the printer may be warming up to adjust the fuser temperature to its baseline. The printer always returns the fuser to this baseline temperature before printing any media from Tray 1. This is done to protect the printer from damage when unspecified media is fed from the multi-purpose tray. Tray 1 is the only printer tray that has this characteristic.

WARMING UP may be displayed when the printer switches between a color print job and a monochrome print job. The fuser temperature is adjusted to accommodate the difference in media feed rate between color and monochrome print jobs. In Monochrome mode, media is passing through the fuser at a rate of up to 24 pages per minute requiring more energy in the fuser than with the color rate of approximately six pages per minute.

How to identify the issue

Verify the source of the media.

Verify the type and size media is being printed.

Print a Continuous Self-Test with standard letter size paper from all sources to verify printer functionality.

It is important to verify that control panel settings are correct:

Tray 1 must be set for Cassette on the HP Color LaserJet 8500 series printer and to the appropriate paper type on the HP Color LaserJet 8550 series printer.

Paper Type must be set for the type of media being used.

Verify in the application that the proper selections are being made. For example, in Microsoft Word where the Page Setup tab must have the proper selections, see the Figure below which shows the selections on the Paper tab that need to be verified.

Figure 1: Page Setup tab in Microsoft Word 1-Paper tab 2-Paper Size 3-Paper source

Finally, make sure the driver is setup correctly:

Make sure that the number of copies is correctly selected from the Application tab.

The number of copies selected in the Application tab will override the Driver Properties tab.

Determine if the issue is specific to a particular application:

If the print job is from any type of spreadsheet or graphic from Microsoft(R) Excel, determine if any shaded or hatch-marked cells are there.

If shaded or hatch-marked cells are in the document, restructure them with other types of fills, or remove them entirely.

NOTE: Excel will process each of these hatch marks as individual characters, and this could cause a variety of error messages, including the WARMING UP message

Verify the settings within the printer driver:

Ensure that the Paper Size and Source are set to the default values (Letter and Autoselect).

Check the Configuration Page to verify that the tray settings are correct.

NOTE: Educate the customer as to why the printer displays this message and that the WARMING UP message means that the fuser is adjusting its temperature for the media being used. This by design, the printer is functioning normally.

© 2005 Hewlett-Packard