Short answer
A THC cartridge with no airflow has a block in the air path or a bad connection to the battery. Four causes cover most cases: thick oil in the center tube, a clogged mouthpiece, a 510 pin that does not touch the battery contact, or oil that leaked into the battery. Warm the cartridge, check the contacts, and test it on a second battery before you return it.
The air path inside a 510 cartridge
Air enters at the base of the cartridge through one or two holes above the threads. It passes the coil, then moves up the center tube and out the mouthpiece. That tube is narrow, often under 2 millimeters. A drop of oil, a piece of lint, or a bent pin can close it. The coil still fires, so the battery light comes on and you get no vapor.
Checks in order
- Cold oil. Distillate thickens below 70 F. Hold the cartridge in your hand for two minutes, or press the preheat button if the battery has one. Preheat runs at low voltage for about 10 seconds.
- Clog in the tube. Take a dry pull with the battery off. If air moves after 2 or 3 pulls, the clog broke loose. Wipe the mouthpiece.
- Mouthpiece. Look for a film of oil, pocket lint, or a silicone plug left on from shipping. Some carts ship with a rubber cap under the mouthpiece.
- 510 pin contact. Remove the cartridge. Wipe the battery contact and the cartridge pin with a cotton swab dipped in isopropyl alcohol. Let both dry. Do not press or bend the pin.
- Over-tightening. Back the cartridge off a quarter turn. Tight threads can push the pin past the battery contact.
- Magnetic adapter. If your battery uses one, the ring must sit at the base of the cartridge. A missing ring adds a 1 to 2 millimeter gap.
- Battery airflow ring. Some batteries have a ring near the top that closes the intake. Turn it to the open position.
- Leaked cartridge. Oil on the battery threads means the cart flooded. Wipe the threads. If the cart leaks again, stop using it.
Test with a second battery
Put the cartridge on a different 510 battery. If it hits, the problem is the first battery: a stuck pin, a dead cell, or a closed airflow ring. If it does not hit on either battery, the cartridge is the problem. This test takes a minute and tells you which part to replace.
What not to do
- Do not push a paperclip, pin, or wire into the center tube. You can crack the glass or shift the coil.
- Do not heat the cartridge in a microwave, an oven, or with a lighter. Heat above 150 F can crack glass and degrade the oil.
- Do not draw on a cart that leaks oil into your mouth.
- Do not use a cart with a burnt taste. The coil is scorched and the hardware is done.
Returns at the dispensary
Keep the receipt and the original package. Return policies vary by state and by store. Many stores replace defective hardware. Some states do not allow returns of opened cannabis products at all. Call the store before you drive over. Ask for the manager, describe the symptom, and give the batch number printed on the label.
Safety notes
The CDC tied the 2019 EVALI outbreak to vitamin E acetate in THC cartridges sold outside licensed stores. State-licensed products carry batch labels and lab test results. Products from unlicensed sellers often do not. If a cartridge leaks, clogs on every battery, or tastes burnt, treat it as defective hardware and stop vaping it.