There are several reasons for a hood to lose suction. Please see if one of the following will solve the problem.

Clean the grease filter regularly

If your hood has a vent connection, it most probably has a non-disposable metallic mesh filter which needs cleaning from time to time. If you don’t clean the filter regularly, grease and dust can breach it and make their way into your hood’s fans or inner walls. This will restrict air flow.

To see where the filter is located and how to remove it, consult your user manual. If you’re having trouble finding your manual, download it here using your product’s model number. 

To clean the grease filter, place it in hot or boiling water with some dish soap or a similar grease-removing agent. Let it soak for a while to allow the grease to soften. Then scrub with a sponge or soft brush. Remove and clean the filter thoroughly once a month.

Some hood filters are also dishwasher-safe. Make sure to dry the filter thoroughly before reinstalling it. 

Replace the carbon filter regularly (non-vented models)

If your hood doesn’t have a vent connection, it will most likely use a carbon filter. Carbon filters are disposable and need replacing from time to time.

Follow the instructions in your hood's user manual on how to remove and replace the carbon filter. If you’re having trouble finding your manual, download it here using your product’s model number.  

It’s recommended that you change the carbon filter every six months. If you cook a lot or do a lot of frying, you may need to change your carbon filter every three to four months. 

Check inside the hood for dirt built-up

If you’ve ensured that the filters in your hood are well taken care of, another thing to check is your hood’s air ventilation. If the hood hasn’t been cleaned for a long time, dust and grease may have seeped through the filters and made their way towards the hood’s fan. Though unlikely, some other foreign object might have been sucked up into the hood, obstructing air flow inside the appliance. 

To make sure that this isn’t the issue, take out all the removable parts of your hood and check the inside. While doing this, give the inside walls a good wipe with a damp cloth. You can use non-abrasive cleaning products or dish soap.

Make sure to dry the inner walls and the filter thoroughly before reinstalling it.

Vent connection

Your hood’s air flow might be obstructed by objects stuck in its vent connection or the vent itself. If you suspect this to be the case, contact an authorised service agent.

Consider technical problems

If the problem continues, your hood might have a technical problem. If you suspect this to be the case, contact an authorised service agent.