hello

having problems with my octavia air con, i think it is the compressor, but i dont wanna remove it if there might be something else causing the problem.

the fault code from vcds reads as below

1 fault found

00898 - control circuit A/C compressor

010 - open or short to plus

any ideas?

By the look of the text you quote, it isn't the compressor itself but the power supply wiring having a fault.

Ian

i have checked the wires running from the switch in the dash to the pump in the engine bay and get continunity on both wires so i assume that the wires are fine. if im right in thinking the pulley on the pump is electro magnetic maybe there is a fault in it?

Is it an Octavia 1 (therefore in the wrong section)?

it is 2007 car.

I'm assuming it's a late Mk1...

If you look inside the aircon compressor pulley, you will see the magnetic clutch plate.

Does the plate turn when you switch on the a/c?

Does the nut in the centre of the plate turn when you switch on the a/c?

It is an Octavia II. Pre facelift.

Does the plate turn when you switch on the a/c?

Does the nut in the centre of the plate turn when you switch on the a/c?

You need to be answering these questions...MKII's dont have the traditional clutch systems and the compressor runs constantly (even on ECON-just at 2% ot normal)

Nothing changes when I put the air con on. I don't see any change in the pulley

If the plate inside the pulley is not turning, then the compressor isn't running.

If it really is a Mk2, then the anti-seize pulley components have sheared to prevent the belt seizing. It is likely, that the compressor has seized. Was this car imported from the south? Is it a taxi?

If it is a Mk1 (or for some reason has the old arrangement) then the clutch is not engaging. If you look at the compressor, there will be a 2-way connector at the back, the wires will run to the front and disappear between the compressor body and the pulley. Is this what you see?

you wont, it doesnt have a clutch.

need to check in MBV compressor current, spec and actual, temp readings of evap sensor, external sensor and interior sensor and shut off code.

If the code is zero, the current is around 0.800amps (iirc) and the temps are all about the same the compressor has had it. needs a new compressor, drier and system flush.

I'm sure it's the mk2. Its a pd140 sport. It's not an import and not a taxi. It's been in the family from new.

can't really get a gd look at it. I would need it on the lift to see it better.

So your saying when the engine is running the centre shouldn't be turning unless the the Aircon is on?!

i am saying as its a MK2 it doesnt have a clutch so the drive will always be spinning.

Tech1e. Is there any chance I could call you when I'm at the car and you can explain in better detail. Only if if suits you though.

Can you check the readings through vcds?!

yes you can check with vcds, just go into hvac which is 08 and then into adv measured values and tick the ones in the above post.

compressor shut off code 16.0

engine speed 800/min

vehicle speed 0.0km/h

standing time 00:08

compressor current actual

compressor current specified 0.000A

compressor speed 0/min

compressor load 0.0Nm

coolant pressure 5.6bar

rad fan activation actual 10.0%

rad fan activation specified 0.0%

engine speed increase OFF

can some one else with vcds and working aircon let me know what there reading are

Edited 10 August, 201114 yr by Badger Driver

compressor shut off code 16.0

First thing to note is you have a shut off code!! :'( and your compressor isnt spinning or loaded :(

My 1.9TDi PD105 Octavia MK2 gives the results below:

At 22degrees

0.0 Compressor Shut-Off Code

0.820 A Compressor Current (actual)

0.820 A Compressor Current (specified)

1000 /min Compressor Rotations

4.9 Nm Compressor Load

10.2 bar Coolant Pressure

34.4 % Radiator Fan Activation (actual)

36.8 % Radiator Fan Activation (spec.)

OFF Engine Speed (increase)

At LO setting

0.0 Compressor Shut-Off Code

0.820 A Compressor Current (actual)

0.820 A Compressor Current (specified)

1000 /min Compressor Rotations

5.7 Nm Compressor Load

11.2 bar Coolant Pressure

42.4 % Radiator Fan Activation (actual)

43.2 % Radiator Fan Activation (spec.)

OFF Engine Speed (increase)

compressor shut off code 16.0

...

shutoff code 16 means that the Regulator Valve(N280) signal is implausible.

The N280 sets the compressor's variable displacement based on evaporator temp. It is not uncommon for these to stick resulting in this error but it is also possible that there is a problem with the wiring to the valve.

so can the valve be free'd up or is it just a replacement

The N280 valve is considered by VAG to be an integral part of the compressor. It is PWM controlled and the wires to it share a 4-pin connector with the alternator signal wires. Check the 4-pin connector, the connector at the N280 and the wires in between. Given that your readout gives zero current my guess is that a break in the wiring is the cause.

Check the centre nut of the compressor is rotating. Although you don't have an electro-mechanical clutch, you do have a shear clutch (also known as a driver clutch or belt protection clutch). The rubber components in the clutch will shear if the compressor seizes. The pulley will continue to rotate, but the compressor shaft and the centre nut will not.

4pin?? i think the wiring connector on mine is 2pin?

Somebody posted this on the N280 valve

Edited 11 July, 201114 yr by xman

4pin?? i think the wiring connector on mine is 2pin?

There is a 2-pin connector at the compressor but if you follow the wires back you will find a 4-pin connector. Pins 1/2 carry the alternator signals and pins 3/4 carry the compressor signals.

Check the centre nut of the compressor is rotating. Although you don't have an electro-mechanical clutch, you do have a shear clutch (also known as a driver clutch or belt protection clutch). The rubber components in the clutch will shear if the compressor seizes. The pulley will continue to rotate, but the compressor shaft and the centre nut will not.

^^^^^

This should still be the simplest thing to check. Get a spanner on the centre nut and establish whether the compressor shaft is seized! Its difficult to tell if it spins without some decent light on it, so with the engine off I got a spanner on mine and found the shaft wouldnt rotate (even though the pulley still rotated with the engine running-this is because of the belt protection). It should rotate without too much resistance with the engine off.

Though I agree and trust rwbaldwin, it does sound suspiciously more electrical than mechanical...

right i fitted a new compressor today and it cleared the short to earth fault code in vcds, however when i took the car to get re-gassed the pressures dont drop so there must be another fault somewhere causing this not to turn on. the compressor shut of code im getting is 12. whats causes this reading?