This is a pretty common problem on the Guardian, and it's usually caused by 1 of two things. Both are pretty simple fixes. The first thing you should try is simply eliminating the wand assemblies from the vacuum cleaner. So remove the hose from the upper wand, and disconnect the lower wand from the power nozzle. Now try connecting the hose directly into the power nozzle and turn on the vacuum cleaner, and power nozzle. Does it work? If yes, then one of your wands has gone bad, and you'll need to replace it. Here's a link to the wands on our website if you need purchase a new Guardian wand;
Electrolux Guardian Replacement Wand Assembly
If the power nozzle still won't come on, then you may have a much simplier problem. This is either a terrible design by Aerus, or they knew this was going to happen, and made it this way so you'd have to take your machine into to have them service it. It's a very simple problem usually.
Look on the neck of the power nozzle. You will see a small circle indent on the front part of the neck located underneath of where the wand connects into the neck. This is actually a cover that hides a screw below. Simply use a small flat head screw driver, and pop off the small circular cap that hides the screw. There is a Star bit screw underneath. I believe it's a T15, but it may be a T10 sized screw. Use I believe a T15 Torx screw driver and remove the screw from the neck.
Once the screw has been removed, Use a flathead screw driver, and pry the front cover of the neck off. It shouldn't take a lot of force, and should come off pretty easily. Once this has been removed, you should see to metal pins, and two lead wires. What happens is the lead wire becomes disconnected from the metal pin, which then prevents the power nozzle from turning on. Simply reattach the lead wire into the metal pin, and snap the front cover of the neck back on. Put your screw back in, and your screw cover (or you can just leave this part off, you'll probably be having to remove it frequently to reinstall the lead wire, lol).
If neither of these two problems fixed your machine, then it sounds like you may have a bad hose assembly. Hopefully this isn't the case, and it's usually not. 9 times out of 10, it's just the lead wire that's come loose. If you do however need to buy a hose, here's a link to the Guardian hose on our site;
Electrolux Guardian Replacement Electric Hose Assembly, Blue Color
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Thanks so much,