MajorCommonElectrical

Volkswagen Polo: 9N air-conditioning compressor lock plate failure

9N air-conditioning compressor lock plate failure is a common electrical fault on the Volkswagen Polo on the 2002–2009 cars, and we rate it major. Putting it right costs $300 to $2,200 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 22 documented faults on the Volkswagen Polo.

Vehicle: Volkswagen Polo
Years: 2002–2009
System: Electrical

This page covers the Volkswagen Polo as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Volkswagen Polo faults22 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph for this fault yet. We would rather show none than show a picture of something else.

What goes wrong

Air-conditioning trouble is common on the 9N, and one known cause is a damaged lock plate in the compressor rather than a simple gas leak. The give-away is air conditioning that works intermittently or stops working altogether, sometimes with a knocking or grinding from the compressor when it engages. It matters because the two causes cost very differently: a regas or a leak repair is a modest bill, while a failed compressor is a large one, and a compressor that has broken up internally can send debris through the system and require the whole lot to be flushed. Establishing which one you are looking at before you negotiate is the whole point.

What you would notice

Air conditioning blowing warm, or working only sometimes
Knocking, grinding or rattling when the air conditioning switches on
Compressor clutch not engaging at all
Squeal from the auxiliary belt when the air conditioning is switched on

How to check it

Where to look. Air-conditioning compressor at the front of the engine, driven by the auxiliary belt

Run the air conditioning for a good five minutes, not thirty seconds — intermittent faults need time to show.
Switch it on and off several times with the bonnet up and listen at the compressor for a knock or grind as the clutch engages, and watch that the centre of the pulley actually starts turning.
Feel the vent temperature at the start and again at the end; air that cools then fades is a different story from air that never cools.
Listen for a belt squeal when the compressor loads up.
Ask when it was last regassed and whether it has been done more than once, because a system that needs regular gas is leaking.

What it costs to put right

$300 to $2,200 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Does the air conditioning blow cold every time?”
“When was it last regassed, and how often has that been needed?”
“Has the compressor ever been replaced?”

Now check the Volkswagen Polo you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

Volksmaster — '8 VW Polo common issues'
WhoCanFixMyCar — Volkswagen Polo problems, common issues and repair costs

Volkswagen Polo buyer questions

Is 9n air-conditioning compressor lock plate failure serious on a Volkswagen Polo?

We rate it major and common on the Volkswagen Polo. Air-conditioning trouble is common on the 9N, and one known cause is a damaged lock plate in the compressor rather than a simple gas leak. The give-away is air conditioning that works intermittently or stops working altogether, sometimes with a knocking or grinding from the compressor when it engages. It matters because the two causes cost very differently: a regas or a leak repair is a modest bill, while a failed compressor is a large one, and a compressor that has broken up internally can send debris through the system and require the whole lot to be flushed. Establishing which one you are looking at before you negotiate is the whole point.

How much does it cost to fix on a Volkswagen Polo?

$300 to $2,200 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Volkswagen Polo years are affected?

Our research records this fault on the 2002–2009 Volkswagen Polo. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Run the air conditioning for a good five minutes, not thirty seconds — intermittent faults need time to show. Switch it on and off several times with the bonnet up and listen at the compressor for a knock or grind as the clutch engages, and watch that the centre of the pulley actually starts turning. Feel the vent temperature at the start and again at the end; air that cools then fades is a different story from air that never cools. Listen for a belt squeal when the compressor loads up. Ask when it was last regassed and whether it has been done more than once, because a system that needs regular gas is leaking. Look here: Air-conditioning compressor at the front of the engine, driven by the auxiliary belt