heating doesn't work anymore it's very small and it takes time before

Hi Laurore,

There isn't just one answer to all of the problems that can cause your heater to not work well. Off the top of my head, here's a list I can think of.

• Clogged heater core
• Defective mixing valve
• Low coolant
• Air in cooling system
• Control knob not working (detached/defective)
• Pinched/bent/obstructed heater hose

The easy things to start with are to check the coolant level in the radiator and visually inspect the heater hoses in the engine compartment for any bends or pinches that could obstruct the flow of coolant.

If those are okay, you will probably have to start taking things apart inside the passenger compartment. Unfortunately, heater cores tend to be buried deep in the dash and frequently require major disassembly to access. Here's a short video giving you an idea of what you may have to remove to get to one.

Nissan Rogue heater core replacement - YouTube

You'll want to start by verifying that turning the heat dial on the dash is actually moving a lever on the mixing valve that controls the amount of water being let into the core, thus regulating the temperature. The control usually consists of a cable running from the knob to the mixer, but can be electrical or vacuum powered on some vehicles. Regardless of the method, the mixing valve should physically move when the knob is turned. You will probably have to disassemble parts of the dash to access the knob and the mixing valve.

After that, check by feel that the temperature coming out of the mixing valve increases as you turn the heat knob up. If that seems to be working, the last and most desperate check is to open up the heater box and physically feel if the core is getting hot when the heat is on high. If everything else is working but the core still won't heat, it will need to be replaced.

All in all, this could be an easy fix, or you could end up tearing the entire dash apart; there's no way to know until you start troubleshooting and locate the problem.

I actually thought of one other thing that can affect the heating. I had a VW New Beetle where the blend door for the AC had gone bad. In that case I could get all the A/C I wanted, but the heat was minimal. So that's something else to add to the list if things to check.