HEVAC error symbol due to Heated Windscreen

**glenhendry** · 21st October 2013, 08:57 AM

Hi there

I have always had the HEVAC error book symbol, but my air con has always worked fine. The Faultmate shows only 2 faults, Heated windscreen short to ground on both sides, but I dont have heated windscreens!!

I can't find a setting that tells it that they are not installed? Also, I did install a UK HEVAC panel to get the heated front seats, but the problems exists with both the Aust HEVAC panel and the UK one. Any ideas?

**RR P38** · 21st October 2013, 10:50 AM

Fuse box, is there a fuse installed for said annoyances?
Check the relays as well, for the screen heater.
Put one in and see if it goes away.........just an idea.
Contact cleaner spray the plugs for the screen heater and the switches in the HEVAC.

Just ideas thats all.

**mtb_gary** · 21st October 2013, 11:51 AM

Glen

Just had a quick look at the RAVE manual:
1

CIRCUIT OPERATION

This operates only with the engine running, which is
determined by the HEVAC panel. In the off state, the
signal is at 12 volts. When the Heated Front
Windscreen is activated, the signal is switched to 0
volts. This provides the ground required for relay 5 to
be pulled in, as there is an ignition feed on the other
side of the coil provided by relay 15. This relay
energises one half of the heated screen elements.
Once relay 5 has been energised, a 12 volt signal is
provided to the coil of relay 4. The other side of the
coil is connected directly to ground, thereby
energising the relay and switching on the other half
of the elements.
There is also a feed spliced from the harness which
provides the petrol Engine Control Module with a
signal that tells the unit there will be a large electrical

load turned on/off.

RR P38 sounds like he's on the right track with the relay and fuses, even though you are not using the heated windscreen the HEVAC panel is still looking for the 12v.

Gary

**flathead steve** · 21st October 2013, 07:35 PM

OH MY GOD What have I done

I thought it couldn't be any harder to work out than a 1928
flathead

WRONG AGAIN

Oh well a bloke's gotta have
a hobby

**glenhendry** · 24th January 2014, 10:09 AM

FIXED! Thanks RR P38, you were right!

I put two yellow relays in the fusebox and the symbol went away next start up. I didnt have to reset any codes. I am so relieved.

I assumed that there were no relays in there because it was a Aust model and they didnt have those relays installed from the factory. However, I have since put in a HEVAC unit with heated seat switches (from the UK), so maybe it assumes that the heated windscreen is fitted?

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