An automatic door not closing is one of the most common faults on a commercial entrance, and it is usually the door doing its job: something tells it a person is still in the way. Before you call anyone, a few safe checks often find the cause. This guide explains why an automatic door stays open or keeps opening and closing, what you can check yourself, and when to call a technician.
In this guide
Safety first
Never tape over, unplug or turn down a safety sensor to make a door close. The sensors stop heavy glass leaves closing on people. If the door is behaving unpredictably, switch it to a safe mode or off and call a technician.
Common causes of an automatic door not closing
1. Something is in the detection zone
The presence and safety sensors hold the door open while they see something in the opening. Common culprits are a mat edge, a sign, a pot plant, a trolley, stock left near the threshold, or a banner moving in the wind. Clear the opening and watch whether the door closes. This is the cause of an automatic door not closing more often than any fault in the mechanism.
2. The mode switch is set to open
Most operators have a mode switch for automatic, hold-open, exit-only and locked settings. If someone has left it on hold-open, the door will stay open, which looks exactly like an automatic door not closing. Check the switch before anything else.
3. Dirty or misaligned sensors
Dust, rain, cobwebs or a knock can make a sensor see a false target. Wipe the sensor lenses gently with a dry cloth and check they have not been bumped. See automatic door sensor types.
4. Debris in the floor guide or track
Grit, a stone or a coin in the floor guide can jam the leaf before it closes. Switch the door off before you clear it.
Why it keeps opening and closing
A door that cycles open and shut is a close relative of an automatic door not closing. An automatic door that keeps opening and closing on its own is usually reacting to something it should ignore:
- Passing foot traffic outside the entrance, because the motion sensor field is set too wide.
- Movement in the zone: flags, plants, signage or a fan.
- Reflections from a shiny floor, rain or glass.
- Vibration from traffic or a loose sensor mounting.
These are adjustments to the sensor field and sensitivity, done by a technician with the door’s commissioning settings to hand.
When it is a mechanical fault
If the opening is clear, the mode is right and the sensors are clean, but the automatic door still will not close, or closes slowly or unevenly, the cause is usually mechanical:
- a worn or slipping drive belt;
- worn rollers or a damaged floor guide;
- a loose end stop or bracket;
- a controller or motor fault.
An automatic door not closing for any of these reasons needs a technician. See automatic door repairs and our automatic sliding door motor guide.
Parts that often fix it
Prices are for MC-125 spares, excluding VAT, at the time of writing (October 2026).
| Part | Price |
|---|---|
| MC-DL8 motion sensor | R3 163 |
| MC-507 safety sensor | R5 588 |
| Nylon floor guide | R546 |
| Main rollers, set of 4 | R4 972 |
| Drive belt, 10 m | R2 778 |
Fitting and setting up sensors needs a technician, because the safety zones must be re-checked afterwards. See automatic door spare parts.
Getting it fixed
In Gauteng, MC Automations attends call-outs within 24 hours, at R1 450 excluding VAT within 60 km, then R7 per km. Book through automatic door call-outs. For other faults, such as a door that will not open, see the automatic door troubleshooting guide.
Preventing the fault
Regular servicing is the best defence against an automatic door not closing. It catches worn belts, rollers and drifting sensor settings before the door gets stuck open. Service automatic doors every six months, more often on a very busy entrance. See automatic door maintenance and automatic door safety. The South African Bureau of Standards publishes the national standards framework for buildings.
Automatic door not closing: frequently asked questions
Why is my automatic door staying open?
Usually something in the detection zone, a mode switch left on hold-open, or a dirty sensor. Check these first.
Why does my automatic door keep opening and closing?
The motion sensor is picking up passing traffic, movement, reflections or vibration. A technician can narrow the sensor field.
Can I turn the sensor down to make it close?
No. Never disable or turn down a safety sensor. Call a technician.
Is it safe to use a door that will not close?
Switch it to a safe mode or off and keep people clear until a technician has checked it.
How quickly can someone come out?
In Gauteng, call-outs are attended within 24 hours.
Coetz™, Unit 2, 84 Ridge Road, Laser Park, Johannesburg. Call 010 412 0062, WhatsApp 076 613 4418 or use our contact page.
Track problems: see automatic sliding door track.
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