Switched on the heated front windscreen this morning as it was frozen and I was amazed how quickly it cleared... the passenger side. The drivers side stayed frozen.

Is it new windscreen time or is there something else which could be causing the issue?

Thanks in advance.

Not sure L322 specifically but I had this problem in my last x type.

I believe it would be abnormal for one side of the whole screen not to work, as usually when they 'fade' over time certain lines stop working. If the passenger side is working fine, i'd be looking a possible electrical problem.

First thing I would check would be the fuses for that side of the screen, in my X type for some reason the fuse for one side of the heated screen was missing, I replaced it and it all worked!

Easy fix I know, but the next things to check would be relay, and then connections to the screen which is probably hidden behind the trim on the A pillar I would have thought! 

It might be something else, but might not.

There are separate connections either side - you can remove the pillar cover to see the connection - it might be that simple.

On the L405 there are 2 connectors - if the plug is in the wrong one, it only does the wiper area, the other does the entire windscreen - I assume it's similar on the L322.

After a quick look in the electrical library, maybe I was wrong.

It seems to be just one relay and fuse, so my thoughts would be possible wiring.

How long have you had the vehicle, or have you had a screen replacement recently? it might just be a case of the fitter has forgotten to plug one side in!

Here is the information about the heated front screen from the electrical library:

Quote:

HEATED FRONT SCREEN (HFS)
DESCRIPTION
General
Operation of the Heated Front Screen (HFS) is controlled by the Automatic Temperature
Control (ATC) ECU via the non latching HFS switch.
When the engine is running and the HFS is selected, the ATC ECU illuminates the LED
above the switch and energises the HFS relay attached to the passenger end of the fascia
cross tube. If not already active, the ATC ECU also activates the A/C compressor and the
blower, and sets air distribution to windscreen. After 10 minutes (when ambient temperature
is
–
15
°
C (5
°
F) or above) or 17 minutes (when ambient temperature is less than
–
15
°
C (5
°
F)), the ATC ECU extinguishes the LED and de-energises the heated front screen relay.
After the heater times out or is switched off, the timer in the ATC ECU is reset to zero.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fusible link 1 and fuse 53 of
the passenger compartment fuse box (C0632) on an R wire. Fusible link 1 (C0592) provides
a constant battery feed to the HFS relay (C0994) on an R wire.
Fuse 53 (C0583) provides a constant battery feed to the ignition switch (C0099 on Td6
vehicles, C0028 on V8 vehicles) on an R wire. When the ignition switch is turned to the
'ignition' position, current flows across the switch (C0099 on Td6 vehicles, C0028 on V8
vehicles) to fuse 34 of the passenger compartment fuse box (C0585) on a G wire. Fuse 34
(C0587) provides an ignition feed to the HFS relay coil (C0994) on a GY wire. The earth path
for the relay coil (C0994) is controlled by the ATC ECU (C1629) on a UN wire.
HFS
When the HFS switch is pressed, a momentary earth path (C1630) is created on an N wire.
If all operational conditions are met (
see 'Description' above
), the ATC ECU energises the
HFS relay. The energised HFS relay (C0994) provides a feed to the LH (C0247) and RH
(C0246) heater elements on a pair of B wires. Both elements are earthed on N wires.

 

i'd go with Alistairs suggestion, check the 2 connections.. ... - .- -.




Y. O. L. O.
.

Not sure on the L322, on the L405 - to remove the pillar, there's a screw behind the plastic airbag tab

If you have a meter, you can test the voltage at the connector - that should tell you whether it's the windscreen or car side.

Cheers for your help guys. Think I need to pull the a pillar trims off and have a look.

It does seem very odd how it's exactly half the screen so I'm wondering if there's a power connection at either side.

I've only had the vehicle since March but it's possible that the previous owner has had a new windscreen fitted at some point and just not noticed / been bothered that only half of it works.

on mine passenger side about 10 lines work and drivers side about 3 or 4. Have deep chips in windscreen tho don't think that helps tho. Get less each year .

Hmmmm, mines the same. Like a line straight down the middle, half clear and half frozen. Thought I needed a new screen.
Hopefully will find a lose connection behind the drivers A pillar.

Are these A pillars easy to unclip and re fix? never removed one before and worried that it will look a mess if it doesn't clip back.

Its right in front of you and can't miss it lol Not Galway but Balmoral green actually
148,000 miles

If I remember correctly, if you pop out the Airbag plastic cover on the A pillar there is a single screw behind it then the cover comes off.

Thanks Paul, you're right.

Looks like previous owner been here before as insulation tape around the plug in connectors.

Seem to have 14v getting to the screen and continuity through the elements.

Will try some contact cleaner and cross my fingers lol Not Galway but Balmoral green actually
148,000 miles

You've inspired me to have a look at mine now!

Hopefully I've just got a connector off / loose.

if its the screen a ball hammer is good for a new screen replacement  _____________________________________________________
Zambezi silver Vogue Se unique

MR GLOVER wrote:

on mine passenger side about 10 lines work and drivers side about 3 or 4. Have deep chips in windscreen tho don't think that helps tho. Get less each year .