Re: Skoda a/c intermittent

Thanks. Your link describes:

"Fresh air intake duct temperature sensor -G89-"

This is pretty similar to "AC/heater air intake temperature sensor" - except that the associated text makes no mention of it controlling the air conditioning.

Does your documentation give expected values - presumably resistance against temperature? I could take it out and measure it ... though if the ambient air temperature sensor is anything to go by it will show the expected values - but at least this would eliminate the sensor itself as being the cause of the problem.

[...]

'My documentation' was just a web page found by Googling.

I am unable to locate the sensor on my copy of Autodata, but if the second garage is still friendly they may be able to give you values from there.

Failing that, best suggestion I can come up with based on the sensor being a thermistor would be to connect a variable resistor in place of the sensor and try various settings to see if you can make the A/C work.

Chris

Interesting - what search terms did you Google with? I've found lots of useless links, but not the one you suggested.

I've also found the Climatronic codes - see separate posting - in translated Polish. Just now I wrote down all the values and will post them in due course. Some are fairly obvious and consistent with other evidence (engine temperature, revs, etc) and others look reasonable (compressor code 08).

I think the air intake sensor is probably adjacent to the pollen filter, so in time I will remove the passenger glove compartment and investigate.

Thanks.

[...]

skoda AC/heater air intake temperature sensor

Chris

Ah yes - that finds the diagram you showed. It also finds my post on

which roughly duplicates what I posted here. Mire later when I write up the diagnostic codes ...

OK so here's a link to a PDF of the diagnostic codes originally described at

Some help in translating the text would be nice. I suspect "shovel" means "flap" in this context.

Cheers,

Some more info - from the diagnostic codes link:

"Main channel:11 - Climate control compressor ...

6 Code disinserito compressor (you see system)"

For me this normally shows 08 meaning "incoming air too cold".

Driving today, after going over a bump the a/c starts working. So I park in a layby and look at channel 11.6 which shows 00, i.e. "compressor working"

Then I look at:

"Main Channel: 4 - External Temperature

0 External temperature (°C) 1 Temp. External line CAN (°C) 2 Temperature inhaled air climate (°C)"

Channel 4.0 shows 19.5C - what I would expect. It's nice and stable.

I drive away and as I leave the layby I can't avoid a pothole. With this bump channel 4.0 fluctuates wildly - anything from -2 to -25 - and of course the a/c stops working. As I drive about this continues to fluctuate wildly.

Channel 4.1 shows about -10 and drifts up and down slowly by a few degrees, so I suspect it comes from a filter.

Channel 4.2 shows 63.5 and never changes, so I've no idea what that means.

So it's time to find the sensor that generates this signal.

[...]

Or, more likely, the loose or corroded connection to it. ;-)

Chris

True, but I'm suspicious that because the ambient air temperature sensor on the front bumper also suffers similar intermittency, I'm beginning to suspect that both sensors share a common earth return. But I can't find any documentation that would prove this, or tell me where that return is.

Any ideas?

Easier to make a new earth return than go hunting for an elusive common one I would have thought.

Tim

But finding it would allow me to prove it is the cause of the fault. Currently I'm just guessing. If they don't have a common earth then the fault is probably elsewhere.

OK I've removed the pollen filter. Nothing near it that looks like a temperature sensor.

I've removed the glove compartment, but nothing looks like the sensor shown in your

- but looking mroe closely at that page the picture of the control unit looks like climatic rather than climatronic, and the general title says "Superb" so, not the same model as mine, which is "Elegance". I suspect the sensor might be nearer the air intake below the windscreen so tomorrow I will have that area apart to look.

The mechanic at the Skoda dealer could not find any documentation showing the location of this sensor!

However the Climatronic diagnostic codes do show this temperature as varying wildly from ambient to about -25C and is notable that it will read correctly for several seconds if I hit a pothole at speed with either left front or rear wheels.

Still looking for the correct drawing ...

[snip]

OP here ...

Talked to the technician at the Skoda dealer in Bury St Edmunds.

He printed out the Climatronic wiring diagram for my vehicle, found by VIN and registration number. This says "As of May 2007" and he thinks it includes my vehicle, registered 5 June 2008. It does not show any sensor for "AC/heater air intake temperature".

He also printed out the summary drawing (S87-0346) which he claims relates to my car. This lists "Fresh air intake duct temperature sensor

-G89-" but then says "only on vehicles manufactured up to 05.05". This conflicts with the circuit diagram from Autodata for vehicles up to

10/08 which shows "B163 AC/heater air intake temperature sensor".

The site

lists hidden diagnostic codes, and Channel 4.0 shows a fluctuating external temperature - usually between -10 or -20 degrees, never the same as the faulty reading on the dash from the sensor on the front bumper. Very occasionally it will show a sensible external temperature and the a/c then works correctly. So I think this indicates a reading from another sensor, other than the one on the front bumper. So I have conflicting information about whether or not there is an "AC/heater air intake temperature sensor".

Can anybody help, please?

Does this sensor exist? If so, where is it?

TIA

If it helps, my BMW with climate control has a sensor inside the front wing at the bottom - so quite prone to damage if you 'kerbed' it hard. It serves the dash outside temperature readout - and the AC. If it had an intermittent connection, it might then work sometimes. But if the dash gauge is reading rubbish, the AC won't work properly.

Fair comment. The sensor in the front bumper has been replaced, and testing with a fixed resistor confirms that it's not the sensor at fault, so it's probably the wiring. Not easy to get at. But very occasionally it reads correctly - when parked in the sun and got very warm it might show +30 degrees - and the a/c then works properly - until I drive off!

The sensor in the air intake to the heater (if it actually exists) does not appear to be affected that way, but sometimes it will read normally if I drive over a serious bump in the road - so that looks like a mechanical problem also - which of course might be the sensor itself. Easy to test by replacement, if I could find out where it is and get access to it.

If either sensor indicates a reasonable temperature the a/c works.

It's fairly unlikely the wiring has failed - unless because of a bad accident. So I'd check all the connectors on route - clean and re-grease with silicone grease. Dunno your car, but most are acessible. But of course it could be a dry solder joint etc in an ECU.

Can't find any connectors en route - I suspect the other end of this loom terminates at the Climatronic unit. But I can't find any sort of diagram or other confirmation of this. Surely such things must exist, if only in manufacturing ...?