Air fryer not crisping? Work through these eight causes

An air fryer is a small convection oven. Everything it does well depends on fast-moving hot air touching the surface of your food, and everything that goes wrong is some version of that not happening. Work through these in order — they are arranged by how often they turn out to be the culprit.

1. The basket is overcrowded

The big one. When food overlaps, the covered surfaces never meet moving air, and the water coming out of the food has nowhere to go — so it sits in the basket as steam and softens everything, including the pieces that were browning nicely. The fix is unglamorous: cook less at a time. A single layer with visible gaps beats a full basket every time, and two quick batches genuinely produce better food than one slow one. If you are batch-cooking constantly, that is a sizing problem rather than a technique problem — see what size air fryer you need.

2. The food is wet

Surface moisture has to boil off before browning can start, so anything you have just washed, marinated or taken out of brine will spend the first several minutes steaming itself. Pat food dry with kitchen paper before it goes in. With marinated food, let the excess drip off rather than tipping the marinade into the basket — pooled liquid in the bottom is the fastest route to soggy results.

3. There is no oil at all

Air fryers are sold on using little or no oil, and that has been over-interpreted. A very light coating — a spray, or a teaspoon tossed through — dramatically improves browning, because oil conducts heat into the surface far better than air does. Frozen food that arrives pre-coated needs nothing extra; fresh vegetables, chicken and homemade chips very much benefit. This is not a health compromise worth worrying about: a teaspoon across a basket is a fraction of what deep frying uses, as we cover in air fryer vs deep fryer.

4. The temperature is too low

Browning is a surface reaction that needs real heat. If you are cooking chips at 320°F because that is what the packet says for a conventional oven, you will get pale, dry food. Most crisping jobs want 380–400°F, and many machines go to 450°F for a final blast. If your food is cooked through but never coloured, raise the temperature rather than extending the time — longer at low heat just dries it out.

5. You skipped preheating when it mattered

Preheating is optional for long cooks and genuinely useful for short ones. Putting food into a cold basket means the first three or four minutes are spent bringing the machine up to temperature, which is exactly the window where you wanted the surface to sear. For anything under about fifteen minutes — reheating pizza, crisping halloumi, finishing chips — run the machine empty for three minutes first.

6. You never shook the basket

Whatever is touching the bottom of the basket is not getting airflow underneath it. Shaking or turning halfway through redistributes the food so every surface gets a turn in the moving air. Machines with a shake reminder — the Cosori Pro Gen 2 among them — exist precisely because everybody forgets.

7. The basket or crisper plate is dirty

Baked-on residue insulates the basket, blocks the holes in the crisper plate and stops air circulating underneath the food. If crisping has got gradually worse rather than being bad from day one, this is a strong suspect. A proper clean usually restores performance — our cleaning guide has the routine that does it without damaging the coating.

8. It is the wrong food for an air fryer

Some things will never crisp in one. Wet batter runs off before it sets, delicate leaves fly into the element, and anything with a high water content and no coating — most raw tomatoes, for instance — will steam whatever you do. That is not a fault. Our guide to what not to cook in an air fryer covers the list.

When it genuinely is the machine

After all that, there are real faults. If the fan is not audibly running, if the machine never gets hot enough to brown anything even empty and preheated, or if it trips your breaker, stop troubleshooting technique and contact the manufacturer — those are warranty conversations. Age matters too: a coating that has worn through and a crisper plate that no longer sits flat both degrade results permanently. If your machine is old and you are replacing it, the current picks are here.