Ford Focus 1.6 Zetec petrol - Air temperature sensor

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Sun 27 Feb 2011 10:13
Ford Focus 1.6 Zetec petrol - Air temperature sensor - Onetap

The heating/AC blower on this stopped working and the dashboard display simultaneously started showing a temperature of -36 degC, or " --- degC", and the ice symbol.

I would assume that the air temperature thermistor/IAT sensor has gone out-of-limits or become disconnected, and that this is stopping the fan working.

Does anyone know where this air temperature sensor is located? I've searched the internet and drawn a blank. Most of the information I've found seems to relate to the US market Focus. TIA

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Sun 27 Feb 2011 10:47
Ford Focus 1.6 Zetec petrol - Air temperature sensor - elekie&a/c doctor

Can you supply model year please?Is this Mk2 2005 on or previous ?

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Sun 27 Feb 2011 11:05
Ford Focus 1.6 Zetec petrol - Air temperature sensor - Onetap

Sorry, forgot that. Registered January 2006, the Mk 2 version.

The resistor pack seems to be a common point if failure on these, but the blower not working on speed 4 (by-passing the resistors) and the air temperature error lead me to suspect the sensor.

Would anyone know what the sensor resistance should be at 20 degC?

Edited by afm on 27/02/2011 at 11:08

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Sun 27 Feb 2011 12:17
Ford Focus 1.6 Zetec petrol - Air temperature sensor - elekie&a/c doctor

The outside air temp sensor is behind the front bumper.Can't see how this could affect heater blower operation.(presume you have manual heat control rather than Eatc.(eletronic auto temp control)hth

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Sun 27 Feb 2011 12:37
Ford Focus 1.6 Zetec petrol - Air temperature sensor - Onetap

It has a bus system, the air temperature sensor data can be used by several devices, e.g., ECU and cabin air temperature control. I will have a look behind the bumper and post back if I make any progress.

I have a fault code reader and will check whether the ECU sensor is also showing a ridiculous value for the air temperature.

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Mon 28 Feb 2011 13:34
Ford Focus 1.6 Zetec petrol - Air temperature sensor - Onetap

I haven't done anything yet, but the air temperature display has started showing the correct temperature and the blower will start giving short sudden bursts on speed 4, mainly when cornering or braking. I now suspect the thermistor is innocent and the blower brushes (?) are knackered. I'll have to dismantle it, Haynes says it's a nightmare!

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Mon 28 Feb 2011 18:26
Ford Focus 1.6 Zetec petrol - Air temperature sensor - Onetap

Fixed, loose connector.

There is a drop down fuse board in the Focus passenger footwell. On this there are a few multi-pin plugs that connect to the underside of the board. The sockets have a plastic clip that, when pulled back, retains the plug and, when pushed forward, releases the plug and levers it out of the socket. There's a similar lever on CPU sockets on PC motherboards.

One of these levers had been knocked forward, partially releasing the plug for the fan, temperature sensor and bonnet switch.

The fuse board should be covered with a felt trim panel, but this had previously been removed to replace a fuse. The Focus power/cigarette lighter socket is cunningly designed to catch 5p pieces and blow the fuse. I'd replaced a fuse and left the trim panel in the boot to be refixed when I had more time. Someone's foot had obviously nudged the plug release lever thing.

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Wed 2 Sep 2015 18:26
Ford Focus 1.6 Zetec petrol - Air temperature sensor - inglaurentius

Hello,

I have a similar issue on my Ford Focus Diesel mk2 2007 -- fan blower not working in any of the 4 speeds and dashboard displying "---degC" with the frost red star indication.

All was working fine untill I replaced yesterday my cabin filter and had to unplug the 3 multi-pin plugs from the cabin fuse board in order to make some space to extract the cabin filter.

Replaced filter and fitted the 3 multi-pin plugs back, started engine and checked wipers, lights, radio, etc... When I started engine I noticed that dashboard was showing "---degC" with the frost red star indication. Tried all 4 blower speeds but no fan movement.

Unplugged the 3 multi-pin plugs from the fuse pannel and checked for any bent pins, cables visualy seem not to be damamged, checked all fuses on that board with multimeter and all show continuity, measured the relay marked "heater" from the engine compartment and is ok. Plugged everything back but same behaviour on blower and environmental temperature dashboard display.

Any suggestions are appreciated.

Thanks.

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Thu 3 Sep 2015 02:37
Ford Focus 1.6 Zetec petrol - Air temperature sensor - elekie&a/c doctor
Have you tried disconnecting the battery for 10 mins?Also check the multi plugs on the underside of the fuse box,as these regularly become dislodged
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Fri 4 Sep 2015 18:12
Ford Focus 1.6 Zetec petrol - Air temperature sensor - inglaurentius
I did a battery reset previously, just forgot to mention it.
However one thing I did not know about is the two underside multi plugs you advised to check as they were covered by a white protective panel. One of them might have been loose.
Fan and environmental temperature sensor work fine now.
Thanks for you help.
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