Wiring for Climatronic Control unit

[Norman Willcox]

My aircon has failed. VCDS shows no faults but HVAC measurements are abnormal.  I found information on an Audi forum that says grey/red core leading to B15 connector pin comes from the evaporator sensor. Resistance between that and the green earth core should be between 370 ohms and 3.2k ohms. Those cores on my Octavia go to pin 8 and 2 respectively on the centre socket. (Pin numbers are marked on the A socket but not on the B socket - so I must  assume that B positions are arranged similarly to A positions). The resistance between grey/red and green cores is just under 15k ohms - well outside the expected range.  Can anyone confirm that the grey/red core is indeed the evaporator sensor wire please?  The picture shows the 3 sockets - A is on the right, B is in the middle.

[langers2k]

You can access the wiring diagrams relating to your exact car for about €7 on erwin.skoda-auto.cz

 

You can 'print to pdf' to keep them so you should only need an hours access

[Norman Willcox]

OK I have found that the grey/red core in the centre socket goes to the left footwell sensor. I discovered this by removing the pin from the socket and then got a fault showing using Ross-Tech VCDS.  So I would really like the wiring information for all the Controller sockets.

I had been aiming to try to fool the controller by connecting a 2.2k ohm resistor between the sensor pin and earth to see if that allowed the compressor to work - but I do need to know the correct pin!

[Breezy_Pete]

What year was the car built?

[Norman Willcox]

Wino - The Octavia 2 was bought in 2006.

[Breezy_Pete]

Looks like the wire you're looking for is red/black, going to pin 11 of a 16 way connector. The other side of the evap sensor connects to earth.

[Norman Willcox]

Thank you Wino. Is the green wire on pin 10 the earth?  I am puzzled because I get an Open Circuit when I use the Cigarette lighter earth, but I get 2.666k between red/black and green. If that is correct I suppose that indicates a temperature of under 10 - that is too low. So if I should really get a reading to Earth, maybe it is telling me that I have an open circuit to (or of) the sensor.

[nige8021]

20 minutes ago, Wino said:

Looks like the wire you're looking for is red/black, going to pin 11 of a 16 way connector. The other side of the evap sensor connects to earth.

 

The earth is via pin 14 of the same 16 pin black connector

[Breezy_Pete]

 

 

Brown/white wire. Commoned to "connection earth in climatronic wiring harness".

[nige8021]

Pin 14 should be a Brown/White wire

[Breezy_Pete]

Can't you look at live VCDS data, seeking a column titled "Compressor shut-off codes". The number in that will tell you why the compressor isn't running if it isn't.

 

See here.

Edited 26 March, 2017 by Wino

[Norman Willcox]

It is running - says VCDS. . I think the freon is under value, but there are other defects, one of the sensors must be duff. It could also be the high pressure sensor.. I had hoped to confirm that the inaccessible evaporator sensor was not the duff one. Thanks for the info - I will look again later. Better half is calling.

[Breezy_Pete]

Radiator fans dong what they should?

 

Don't bother answering that now, answer the call.

[Norman Willcox]

Thank you everyone for your posts.This morning I measured the resistance of the evaporator plate sensor – 1.66k Ohms which is a reasonable value for the ambient temperature so a nice relief – short lived! I feel a bit of a fool! I have found that the compressor shaft is not turning. VCDS told me that Compressor Rotation was 1600rpm and I believed it. My eyeball, with a mirror on a stick, says different! It seems that OBD Compressor Rotation is meaningless. Here is a recap. Car is 11 years old. After 7 years the aircon became weak. I had it re-gassed but that made little difference. A year later operation became intermittent but never cold enough. This year aircon stopped working completely, hence my efforts to diagnose the problem.

I note that fan activation is stated to be 9.6% but neither fan ran during my tests from cold start-up I wonder what that reading means.

Address 08: Auto HVAC (1Z0 907 044 H)

10:55:57

1500 /min Engine Speed

0.820 A Compressor Current (actual)

0.820 A Compressor Current (specified)

1900 /min Compressor Rotations

0.9 Nm Compressor Load

4.2 bar Refrigerant Pressure

9.6 % Radiator Fan Activation (actual)

0.0 % Radiator Fan Activation (spec.)

15.0°C Fresh Air Intake Temperature

16.0°C Right Outlet Blower Temperature

15.0°C Evaporator Temperature