Rear Screen De-Mister Not Working

[UnHandyAndy]

I bought a Mk 3 Leon at a year old (64 Plate) and realised the following winter that the rear element wasn't heating. Stupidly didn't return it to the dealer as it wasn't bothering me that much, but decided to finally tackle it this week, as like most folk had plenty time on my hands..... Having looked on here, there are quite a few instances of this and it seems, like mine, could have left the factory like this, but I did check the fuse and relay just in case, both fine. I looked at the Leon Workshop Manuals (in Resources) and removed the interior boot trim in about 5 minutes. The pictures show a white module, which I found did not have the right hand side plug fitted, it was loos inside the trim panel. I popped it back in, problem solved. I THINK the module is a radio amplifier, but don't quote me and I've no idea why the screen element would be powered through it. Re-fitting the trim was a fiddle, but as long as you make sure all the clips that stick in the body are removed and re-fitted to the trim first, it wasn't more than 10 minutes to replace. Can anybody confirm what the white module is? If you zoom in the part No is 5Q0 035 570, which breakers are selling as a radio amp. (radio worked fine before and after the 'repair', btw).

 

[RUM4MO]

Some of these wires are quite a heavy gauge, so are probably the supply to the rear screen heater, as the preamp was still connected to the heater element, it probably performed okay as an aerial, so what you have found does make sense. I've only ever had saloon cars or I've only needed to look for or connect to the rear window heater in a saloon (B8 S4) and they tend to have the preamp wired/plugged into the element directly - but as your car has an opening rear hatch then I can see why SEAT has chosen a different way of doing things.

I owned a VX Cav GSI 2000 16V 4X4, I bought it at 9 months old, when it was used in its first winter I discovered its rear window heater did not work so I removed the rear side trim panels, under one I found the +12V supply heat connector secured to the car's body using sticky tape, removing it from that and plugging it in got the heated window working for the first time!

Edit:- maybe the previous owner had used a dash camera with a rear camera as well, and found that the rear camera interfered with the radio reception, and discovered that it they removed the heater supply, the radio worked okay - just a thought that is all!

 

[UnHandyAndy]

Some of these wires are quite a heavy gauge, so are probably the supply to the rear screen heater, as the preamp was still connected to the heater element, it probably performed okay as an aerial, so what you have found does make sense. I've only ever had saloon cars or I've only needed to look for or connect to the rear window heater in a saloon (B8 S4) and they tend to have the preamp wired/plugged into the element directly - but as your car has an opening rear hatch then I can see why SEAT has chosen a different way of doing things.

I owned a VX Cav GSI 2000 16V 4X4, I bought it at 9 months old, when it was used in its first winter I discovered its rear window heater did not work so I removed the rear side trim panels, under one I found the +12V supply heat connector secured to the car's body using sticky tape, removing it from that and plugging it in got the heated window working for the first time!

Edit:- maybe the previous owner had used a dash camera with a rear camera as well, and found that the rear camera interfered with the radio reception, and discovered that it they removed the heater supply, the radio worked okay - just a thought that is all!

Thanks @RUM4MO , good insight and extra info there. A spanner genius I am not ?, will be a help to anyone else with this issue.

 

[RUM4MO]

I'm sure if I was completely on the wrong track someone would come along with a better bit of logic, I don't mind being corrected as we can all gain from that.