Why there say tray full red light - FoodSaver Smart Seal Vacuum Sealer V3825

That can mean the bag is full.

Depends on which model you have. If it's a red light it might be your full bag indicator. If it's glowing red you might have a clog somewhere .

Hair dryer. Remove both tray inserts and dry thoroughly, paying special attention to the sensor area in the center of the upper tray.

Hi.

If the red light is solid, that means that the Roomba is near to full discharge. If the light is flashing red, then the Roomba is completely out of charge.

If the Roomba is fully charged, then there may be a fault.

Here full list of light codes:

Pulsing Amber - Charging
Green - Fully Charged
Amber - Partially Discharged
Red - Almost Fully Discharged
Flashing Red - Fully Discharged"

Here manual

See also
Roomba DISCOVERY MODELS' DIAGNOSTIC TESTS

The red light will also come on when there is a blockage in the pipes leading to the bag compartment. To test that the light is working correctly, you can unplug the flexible hose from the top of the bag compartment then switch the machine on. The red light should be off, but will come on if you block the hole with your hand. If that test shows the light is working, you need to search for a blockage - which is most likely to be in the flexible hose, but can be in the rigid plastic tube or in the base of the machine (turn it over and look in the little trap-door). Clearing a blockage from the hose can be difficult - you are more likely to be successful if you can devise a way to pull it out rather than trying to push it (as with a broom handle, for example), because pushing may just compact it. Good luck!

There is a shampooer head with shampooer brushroll, water tank, small hose that hooks to the tank, collection tray

Need to use the Kirby shampoo. It goes down as wet suds but you pick up the suds with the vacuum when it drys. Fill tank adding 1 cap full of soap (kirby soap only) per level on the side, this attaches on the side where the bag is attached

After using the shampooer you need to reattach the vacuum bag and main brushroll nozzle as though you were just vacuuming up dirt.

Instructions:

Lift the front of your kirby up (front part with light) open the handle on the dail in the front (if epquipt), remove the power head, put on height adjustment on highest level, turn dial on front of power head until you see 2 red arrows facing each other, unlock by turning knob, power head should come right off, get shampooer out the power head for shampooer with collection tray, make sure dial is set red on red, put on front of Kirby and lock in, turn dial to green on green arrows, fill tank adding 1 cap full of soap (Kirby soap only) per level on the side, this attaches on the side where the bag is attached, line up arrow and notch and turn, to hook up hose put Kirby down to lowest level, notched end of hose hooks in on tray other end on the tank,on/off switch refers to the foam, Turn machine on to lay the foam & scrub carpet, take shampooer back off to extract the foam once it's dry.

Good luck.

Most likely the hose or the inlet down by the brush roll has a clog in it. The red light indicates a full bag, but if there is a clog, then it thinks it has a full bag.

Not sure if yours is a 4499B, couldn't find in the parts list any red light. But most times when there is a red light it is telling you that if it had a bag, it would be full, but in your case, maybe you have a cogged filter and inlet down by the brush roll.