e36 318ti Aircon and Heated Rear Screen

[far4ngn 14]

My heated rear screen doesnt function at all and neither does the aircon, both circuits are driven from the same moulded switch and although it illuminates to say its working neither system does anything.

Any idea on the best way to check the wiring or the relays?

[hotwire 352]

For a start - what car are we talking?

[bmw.maniac 1]

For a start - what car are we talking?

Title says: e36 318ti

[jochen 4]

Sounds like you have the IHKA (electronic control).

Switch nighttime illumination is completely separate from the function of the switch, so the fact that the switch is illuminating with the dash lights only tells us the switch is plugged it :-)

The switch assembly with the rear defogger also has the RecircAir and AC switches in it.

They are both powered from fuse F23 (5A) in the fuse holder in the engine bay. Check it.

You know the fuse is OK because it also powers the Recirc, Defog, and AC indicator lights.

If any of these lights work when you activate the switches, then fuse F23 is OK.

Defogger is switched on by relay K13 (also in the engine bay power box)

Make sure you hear it clicking when you switch defogger on and off.

Defogger power comes from fuse F6 (30A)

If switch and relay and power are OK, then look for power at the defogger elements and check condiiton of heater elements.

As for the AC, give us some more info

Does the fresh air blower work on all levels?

Does the AC compressor kick in?

Does the AC indicator light illuminate?

The AC system is a bit more complex: the AC compressor is switched on by the engine control unit (DME) upon instruction from the IHKA control unit.

Exact cableing etc varies with model years - so tell us your model year and describe in more detail exactly what climate control system you have.

There are pressure switches that will cause safety cutout of the AC system if you have under or over pressure (under = under 1.6bar, over = over 31bar).

Edited July 1, 2008 by jochen