HP OfficeJet Pro 6978 / 8025 Missing Cyan: Why Blue Won't Print Even After Deep Cleaning

Question

I have an HP OfficeJet Pro 6978 / 8025-style printer that stopped printing blue, which means I have not been able to print colors properly for almost a year. During that time, I mostly printed in black only. I recently tried to fix the issue before replacing the printer. I followed the unclogging method from your video, performed four deep cleaning attempts, moved the printhead over wet paper towel pads, ran many Clean Printhead cycles, and worked on the printer for about five days.

The cyan/blue still does not print at all. The printer's cartridge report says the cyan cartridge is almost empty, but I weighed the cartridge and it is actually the fullest color cartridge. It is also a new cartridge. Could this be an electronic or technical issue instead of a mechanical clog, since the printer seems unable to detect or read the ink correctly? Is there still hope for reviving the printer?

Answer

In your case, the missing color is cyan, or what most people call blue. Since the printer has been unable to print cyan for almost a year, there are several possible causes, and they do not all have the same solution. The issue can be caused by a severe clog, but it can also be caused by ink starvation, a dried internal ink path, a bad cartridge, poor cartridge chip communication, air in the system, a damaged printhead, or even an electronic failure in the printer's printhead control circuit.

The first thing to understand is that the printer's "almost empty" message does not always mean the physical cartridge is actually empty. HP printers usually do not weigh the cartridge or directly measure the liquid ink inside. Instead, they rely on chip data, estimated ink usage, cartridge history, and firmware logic. Therefore, it is possible for a cartridge to feel or weigh full while the printer still reports it as low or nearly empty. That does not automatically prove that the printer has an electronic failure. It may simply mean the chip or ink-level estimate is no longer matching the actual ink volume.

If the cartridge is new but the printer reports it as almost empty, I would first suspect one of these cartridge-related issues:

The cartridge chip may not be communicating properly with the printer. You can try removing the cartridge, turning the printer off, unplugging the power cord, waiting a few minutes, then reinstalling the cartridge. Also inspect the copper-colored contacts on the cartridge and inside the printer. If there is ink residue, oxidation, or debris, gently clean the contacts with a lint-free cloth slightly dampened with distilled water or isopropyl alcohol. Let everything dry fully before reinstalling.

The cartridge may be defective even if it is new. This happens more often with remanufactured, refilled, third-party, or long-stored cartridges. The cartridge may contain ink, but the outlet sponge, internal vent, or chip can still fail. If the cartridge is not venting correctly, ink cannot flow out even when the cartridge is full. A simple test is to try a known-good HP cyan cartridge if you have access to one. If a different cartridge immediately starts supplying cyan, then the problem is likely cartridge-related rather than printhead-related.

The printer may remember the previous cartridge's low-ink status. Some HP cartridges and printers track estimated usage in a way that cannot always be reset simply by refilling or replacing ink in the same cartridge body. If you are using a refilled cartridge or a cartridge that was previously recognized as low, the printer may continue treating it as depleted.

However, the more serious part of your case is that cyan does not show up at all, even after multiple deep cleanings and wet paper towel treatments. If a color is completely absent after that much effort, the problem may be deeper than a simple surface clog.

On HP OfficeJet Pro 6978, 6900-series, 8020-series, and 8025-style printers, the printhead has very fine nozzles. If cyan ink sat unused for close to a year, the ink can dry not only at the nozzle plate but also inside the internal ink channels. Once the internal channel is dried or blocked, normal cleaning cycles may not be strong enough to pull ink through. Running many Clean Printhead cycles can sometimes help a mild clog, but after a certain point, repeated cleanings mostly waste ink and may overfill the service station or waste ink area.

The wet paper towel method is useful when dried ink is sitting on the bottom surface of the printhead. It softens dried ink around the nozzle plate. But if the blockage is inside the printhead, or if the cyan channel is air-locked, dried upstream, or electrically damaged, sitting on a wet towel may not restore flow.

There is also a difference between a clog and an electronic failure. A clog means the printer is trying to fire the cyan nozzles, but ink cannot physically pass through. An electronic failure means the printer may not be firing the cyan nozzles correctly at all. This can happen if the printhead's cyan firing circuit is damaged, if the printhead ribbon/circuit connection is damaged, or if the printer's mainboard is no longer sending the correct signal. Unfortunately, from the outside, a severe clog and a dead color channel can look almost the same: the color is completely missing.

Here are a few ways to narrow it down.

First, print a Print Quality Diagnostic Page or nozzle check pattern. If cyan is completely blank with no dots, no streaks, and no partial recovery after cleaning, that is more concerning than a weak or broken cyan pattern. A weak, streaky, or partial cyan pattern usually means some ink is flowing and there may still be a recoverable clog. A totally blank cyan block after many cleaning cycles may mean the channel is either completely blocked or electronically dead.

Second, check whether the cyan ink outlet is actually supplying ink. Remove the cyan cartridge and inspect the outlet area. There should be evidence that ink can wet the outlet or sponge area. If the outlet looks dry, the cartridge may not be feeding. If the cartridge outlet is wet but the printer still prints no cyan, the problem may be in the printhead or ink intake.

Third, avoid running endless cleaning cycles. After several cycles, the benefit usually drops sharply. Too many cleanings can consume the other colors, saturate the maintenance area, and create additional mess inside the printer. Since you have already done four deep cleaning attempts and many Clean Printhead cycles over five days, I would not keep repeating the same software cleaning process.

Fourth, consider a more controlled printhead flushing approach, but only if you are comfortable with hands-on repair. Cyan may need to be flushed from the correct ink intake port using proper cleaning fluid and gentle pressure. This must be done carefully. Too much pressure can delaminate the printhead, damage seals, force fluid into areas where it should not go, or create cross-contamination between colors. If the cyan channel is severely dried, soaking and flushing may need to be repeated patiently, but there is no guarantee.

Fifth, consider the possibility that the printhead has reached the point where replacement is more practical. HP 6978 / 8025-type printers can sometimes be revived after long periods of inactivity, but not every unit can be saved. If the cyan channel has been dry for almost a year, the dried pigment or dye residue may have hardened inside the microchannels. If the nozzles overheated from firing without ink flow, the cyan nozzle section may also be permanently damaged. Ink acts as both the printing fluid and part of the cooling process. When a thermal inkjet nozzle fires while starved of ink, it can burn out.

Regarding your thought that this may be "technical" rather than mechanical: yes, that is possible, but the incorrect ink-level reading alone does not prove it. The ink-level problem may be cartridge chip or printer estimation logic. The missing cyan may be a separate physical clog or starvation issue. But when both symptoms happen together, I would check the cartridge first, then the contacts, then the printhead ink path, and only after that suspect electronics.

If you see any HP error codes or messages, those would also help narrow the direction. For example, a cartridge communication issue may show messages such as "Cartridge Problem," "Ink Cartridge Problem," "Remove and Reinstall," "One or more cartridges appear to be missing or damaged," or similar cartridge-related alerts. Printhead-related problems may show "Printhead Problem," "There is a problem with the printhead," or sometimes an alphanumeric HP error code depending on the model and firmware. In your description, you did not mention a specific error code, but you did mention the cyan cartridge reporting almost empty despite being physically full. That points us toward cartridge recognition, chip data, or ink-estimation issues, while the total absence of cyan points us toward either a severe cyan clog, ink starvation, or a failed cyan channel.

If I were troubleshooting this printer on the bench, my order would be:

1. Test with a different known-good cyan cartridge, preferably a genuine HP cartridge if possible.

2. Clean the cartridge contacts and printer contacts.

3. Print a diagnostic page to confirm whether cyan is completely absent or partially present.

4. Check whether cyan ink is reaching the printhead intake.

5. Attempt a careful cyan-channel flush if there is evidence of clogging.

6. If cyan remains completely absent after verified ink supply and controlled flushing, suspect printhead damage or electronic failure.

The fact that you worked on it for five days and still got no cyan at all means you are no longer dealing with a simple maintenance cleaning. There may still be hope, but I would set expectations carefully. A printer that has been missing one color for almost a year has a much lower recovery chance than a printer that only clogged recently. If the printer is otherwise valuable to you, and if you enjoy repair work, it may be worth trying a careful cartridge swap and controlled cyan flush. If you need reliable printing soon, replacing the printer or replacing the printhead assembly may be more practical.

Addressing printer issues can be a complicated process because many of these problems require hands-on inspection and testing. Because of that, we are not able to provide remote troubleshooting, personalized repair guidance, or direct support for printer repairs. However, we do offer in-person evaluation and repair through our local diagnostic facility: BCH Technologies Printer Repair Service [https://bchtechnologies.com/printer-repair-service]. Due to high demand, repairs are handled on a first-come, first-served basis, so it may take a few weeks before your printer can be dropped off or evaluated. Our service is structured to repair either the whole printer or specific parts, with instructions provided for how to proceed. That said, we understand that our rates may not be the most economical option for every situation. For that reason, we strongly encourage self-help through online research. A good starting point is YouTube, including our own homepage at BCH Technologies on YouTube [https://youtube.com/@bchtechnologies]. Once you are on the channel page, use the search icon next to "About" on the right-hand side of the menu bar to search for the specific topic or printer model. I receive many questions every day asking where to find videos on particular repairs, and after making videos for the past nine years, it is difficult to remember every individual video. YouTube's search function is usually the most efficient way to find the right video, and it may also suggest helpful videos from other creators.

Thank you again for watching our video and for sharing such a detailed description of what you tried. I know it is frustrating to spend that much time and still see no cyan on the page, but your careful testing already gives us a much clearer picture of the likely causes. I truly appreciate your support and hope this helps you decide whether the printer is worth further repair or whether it is time to move on to replacement.