Heater Blower, Quick question
Moderator: RichardW
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windysurferuk
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Heater Blower, Quick question
Am I right in saying if my rear demist light lights up but my heater fan motor is not working then it is not the ingition switch problem?
Xantia 2.1TD SX 130000
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marsalek
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- My Cars: Xantia X2 HDi109
C5 X7 HDi240 - x 15
Not sure, but if the rear window is warm AND the heater blower is not working, then it is IMO not in the ignition switch. (In other words, am not sure, if the demist light is on the same circuit as the heating itself.) Ignition switch makes that trouble on Xantias only in Mk1. Mk2 does not suffer from that at all.
Karel
Karel
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windysurferuk
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The rear demister light lighting is not coming from the ignition switch’s rear demister and heater fan motor switch contact.
It’s lit from the switch’s ‘ignition’ and ‘start’ contact, third from the left on the picture of the switch.
The demister light will come on even if the demister relay/heater fan contact is completely open.
The demister/heater switch contact operates a relay that feeds the demister current from another un-switched source.
The heater fan current originally passes through the ignition switch, and when that fails, the output from the switch is low, causing the demister relay to lack voltage to keep it energised.
That’s the fourth contact from left on the switch picture.
You could have a situation where the demister will work when the heater fan is turned off, as the switch contact is still good for the low current to energise the demister relay, but will fail when the high heater fan current is added to it.
You could try the demister by itself, without heater fan.
If that works, switch on the heater fan next, and if that doesn’t work and stops the demister, then the switch is dodgy.
If the demister doesn’t work by itself, meaning not heating despite the light being lit, it can still be an open heater on the rear window, or a broken wire in the flexible loom going into the top of the rear hatch.
The demister relay is item 3 in the picture, and can be checked for clicking when switching on … hearing and feeling.
Since your heater fan doesn’t work, it’s most likely to still be the ignition switch.
It needs modifying with a relay, and if that’s already been done, they will have used the original demister relay/heater fan motor contact that’s packed up for good only now, as they sometimes do.
Relay modification here:
http://www.frenchcarforum.co.uk/forum/v ... hp?t=21372
It’s lit from the switch’s ‘ignition’ and ‘start’ contact, third from the left on the picture of the switch.
The demister light will come on even if the demister relay/heater fan contact is completely open.
The demister/heater switch contact operates a relay that feeds the demister current from another un-switched source.
The heater fan current originally passes through the ignition switch, and when that fails, the output from the switch is low, causing the demister relay to lack voltage to keep it energised.
That’s the fourth contact from left on the switch picture.
You could have a situation where the demister will work when the heater fan is turned off, as the switch contact is still good for the low current to energise the demister relay, but will fail when the high heater fan current is added to it.
You could try the demister by itself, without heater fan.
If that works, switch on the heater fan next, and if that doesn’t work and stops the demister, then the switch is dodgy.
If the demister doesn’t work by itself, meaning not heating despite the light being lit, it can still be an open heater on the rear window, or a broken wire in the flexible loom going into the top of the rear hatch.
The demister relay is item 3 in the picture, and can be checked for clicking when switching on … hearing and feeling.
Since your heater fan doesn’t work, it’s most likely to still be the ignition switch.
It needs modifying with a relay, and if that’s already been done, they will have used the original demister relay/heater fan motor contact that’s packed up for good only now, as they sometimes do.
Relay modification here:
http://www.frenchcarforum.co.uk/forum/v ... hp?t=21372
2002 C5 2.0i AL4 230,000 km 76372389