If your Hikvision camera shows dark at night you may consult this article for a few possible solutions. The dark image at night may be caused by: a faulty IR block, a faulty IR cut-filter, image settings issues or incorrect installation.
In come cases the image shows dark because the IR block is dead and doesn’t lit the area where the camera is pointed at. All the Hikvision cameras have a light sensor which turns ON the IR block automatically when it gets dark. And subsequently it turns OFF when the environment gets bright again.

To find out whether the IR block works fine, cover the light sensor with a finger (for dome camera it is recommended to remove the glass dome and have direct access to the light sensor. Normally the IRs should glow red, make a click noise and then a few seconds later turn off. If so, that means the IR on your camera works properly. If the IRs don’t turn on than you need to replace the camera.
Sometimes only a few of the IRs don’t work, let’s say 7 our or 20 IR pieces on the IR block are burned. In this case the picture will be dark because the camera doesn’t get enough light from it’s IR block. You need to either replace the IRs or replace the whole camera.

In a few cases the dark image is caused by incorrect image settings. Access your camera directly via web browser and go to the image settings to do the adjustment. Under shutter speed, adjust the shutter value to 1/12 sec. After the setting is saved, adjust the shutter setting to 1/30. Verify if the image is clear. You may need to do a little testing till you are pleased with the image.
So, you say that if the IR block doesn’t work properly I have to replace the camera.
In my case all the IR leds are off even if I can hear the click noise.
Is it normal that the IR block stopped working after less than 2 years? What’s the lifetime of the IR block?
I’m quite disappointed. It is not acceptable.
IR block lifespan usually goes 5-10 years. Check if your camera is under warranty.
Hi,I have taken your advice and covered ir block
and the red lights come on and start showing the image in night vision but now it’s gone dark it’s not switching to night vision.I have moved the camera recently could I have disturbed something?
Thanks
Looks like your power supply is not providing enough juice for the cameras. That may be the reason why the IR block is not turning on at night (not enough power).