I replaced the air con high pressure sensor on my Mk2 Octavia, old one was badly corroded inside. Tested the air with no joy, discovered there's no gas in the system.

I noticed the revs don't drop when I turn the air con on. So before I go and buy gas I'm wondering does the compressor still kick in, and so causing the revs to drop, if there's no gas in the system, or might there be another issue stopping the compressor kicking in?

If the system senses no gas pressure the compressor is not commanded to operate.

There isn’t a clutch on the compressor so doesn’t ‘kick in’ as such. 

So what does that mean, am I wrong in thinking you see a drop in revs when you turn on the air con?

Depends on the loading of the compressor

I had the same issue last year, just as the heat wave kicked in. Went to halfords for a regas, which failed to hold pressure; they instantly refunded me even though they'd put the gas in and collected it back so I wasn't out of pocket.

Luckily, or unluckily for me the sensor sheared off when I tried to change it which meant I had to replace the pipe.

This turned out to be my main issue as I found the pipe had rubbed and got itself a hole which was leaking gas. 

There is a "hidden menu" on the climate control system, I'm sure in the time it will take me to find it again someone will be able to post it for you, it gives pressures etc

I had the same issue last year, just as the heat wave kicked in. Went to halfords for a regas, which failed to hold pressure; they instantly refunded me even though they'd put the gas in and collected it back so I wasn't out of pocket.

Luckily, or unluckily for me the sensor sheared off when I tried to change it which meant I had to replace the pipe.

This turned out to be my main issue as I found the pipe had rubbed and got itself a hole which was leaking gas. 

There is a "hidden menu" on the climate control system, I'm sure in the time it will take me to find it again someone will be able to post it for you, it gives pressures etc

 

Long and short, get a regas if it fails to hold the problem wasn't just the sensor and you'll get a refund

Cheers lads. Refills the first port of call!

On 03/08/2019 at 17:05, Tech1e said:

There isn’t a clutch on the compressor so doesn’t ‘kick in’ as such. 

 

On my vRS, tried everything on the hope it wasnt a failed compressor as they Cost a fortune. The conpressor will not engage if theres no gas detected. If gas is available then the engine (in my vRS) will make a very slight differentiation in sound but you really need to listen for it. I had to replace the pipes and condenser which was damaged and split by stone chips. Even after this it didnt work so I gave up but it started working a week later and has worked since lol. Most reputable garages will have a machine that will run green dye through the system to check for leaks in pipes so would be worth doing this as it will also refill your AC gas too.

 

Edit: A VCDS would help determine the bar pressures of the refrigerant if it still doesnt work and whether theres a steady current going to the compressor etc if your refill fails.

Edited 7 August, 20197 yr by JacksVRS

I've been here. I had it re-gassed by an incompetent garage, it stopped working after a few days, I went back and they couldn't find any leak from the dye. They wanted to charge £45 for an electronic diagnostic. I wasn't filled with confidence so had a mate do the diagnostic for free.

 

It showed low pressure but it rushed out when we touched the valve open momentarily. 

 

I replaced the pressure sensor and stripped the thread of the pipe which led to the need for a new pipe. 

 

I went to a competent garage which found an obvious leak in the condenser and replaced the pipe I bust which came with another sensor on it from Skoda!

 

I had to pay for another re-gas too.

 

My lesson was take it to a proper garage. Mine was a Bosch Service Centre. Not cheap but no issues as a result!

 

Kirkynut 

OP How did you get on?

When mine gave up the ghost 2 1/2 years ago, it was the N280 valve on the compressor, could not find a replacement so I had to change the compressor, they recommend you change the drier pack too, problem, Skoda no longer do the plastic nut type now, so I had to have a new condenser too, did all the work myself, no leaks and touch wood , its' worked ok ever since. Got the parts from ECP.

 

 

Trev