Goodday,

 

I have a 2006 Octavia (2.0 FSI), with less than adequate AC. 

 

Temperatures here reach high 30's & it takes forever for the AC to start cooling properly. I have fiddled at repair shops with Discharging & Recharging gas & compressor oil but with no resolution.

 

Some issues that I faced are:

 

·         Long period before AC starts pushing cold air. (It seems that the compressor is delayed until certain telemetries are available to the ECU.)

 

·         Somedays, the AC works fine, others it doesn’t cool well, not to mention the days where the AC works fine, then takes a break for a couple of minutes then works again

 

I bought a thermometer & stuck the gauge inside the AC vent and monitored the AC performance for 3 days.

It averaged around 10 degrees Celsius (mid 30 degrees outside temperature), I thought that driving on the highway would reduce the air temp (Due to more flow to the evaporators & High RPM), yet the result stayed the same. (Circulation Closed)

Btw, the refrigerant amount is adequate based on feedback from the repair shops, (don’t have the exact reading). Also, car history showed that the AC compressor was replaced (I bought it second hand)

 

 

My question is the following,

·         What air temperature should be at the air vents? (I suspect it should be below 7 degrees), because with the high temperatures over here, 10 degrees at the vent is not adequate to “Really cool” the cabin temperature.(cabin temperatures reaches > 50 degrees Celsius under sunlight)

·         Does the ECU control the temperature set point in which the Compressor works? (to my understanding the Compressor on the Octy II is  clutch-less and has a solenoid valve that regulates the refrigerant gas flow. How long the valve stays open or closed is most probably programmed on a temperature set-point.

·         What telemetries can show me what’s wrong with the AC on “VAG/VCDS” system, noting that there are no error logs when diagnosed

 

Sorry for the long post & many thanks… :|

 

Saleem

 

Assuming similarity with the Fabia system from the same time period, there's a temperature sensor at the evaporator, which is used to prevent condensation freezing, by reducing the (compressor) cooling power if the temperature gets too close to 0°C.  If that temperature sensor wasn't quite giving the correct resistance according to the true temperature, in the direction that made the relevant ECU think the evaporator is colder than it really is, your situation might be explained.  How to know for sure whether this thermistor is giving a good reading or not, I don't know. 

I guess VCDS can display what it's reading somewhere, but you'd need to know what the real temperature is in that location where the sensor is, somehow?

Could just try another sensor if it isn't to hard to access (a bit awkward on MK1 Fabia, no idea on Octy).

Many thanks.. I will try finding out some schematics of where exactly this sensor is located and try checking it out.