RS2 intermittant A/C

[Samppa]

Summer is coming so Im bringing this back from the dead. Still have the same codes, damn it. Tried a new MFS today, didnt actually install it but just connected the wires and grounded the sensor. Still the same codes, ******.. Running out of ideas here..

[Graham]

It sounds like there is too much refrigerant in the system. There is 2 sensors on the comp to condenser line just in front of the main radiator, one is low pressure, one is high pressure, and the range is only 50psi between the lower and higher sensor.
From what you say when it is stood still the pressure increases as there is not as much airflow (Cooling) capacity, your reliying on the fan to cool the system. Once the pressure gets up to the high pressure switch setting, the air con cuts out until the fluid cools and drops in pressure, where it cuts in again. If the opposite happens I.E. it cuts out when your driving then the fluid level is too low, or you have a leak which causes the pressure in the system to drop below the low pressure switch level, again causing it to cut out. When your sat stationary the low fluid level system will be working as the pressure increases when your stood still

[Samppa]

The system is de-pressurised now.. One AC pipe missing

[Samppa]

Ok, I found the solution for my problems. 15pin Red connector under the dash was loose. Put it back and the codes changed from .1 to .3, sporadic open. Now I can read the sensor values from climate control unit. 22.1 disappeared and 22.5 came in. Also outside temp re-appeared above steering wheel.

22.5 Compressor re-engagement circuit, VAG 1551 Scan Tool function

Does this mean that I need to reset the above with VAG-COM or go to dealership, after that it should start to work. I hope.

[alg]

Ok, I found the solution for my problems. 15pin Red connector under the dash was loose. Put it back and the codes changed from .1 to .3, sporadic open. Now I can read the sensor values from climate control unit. 22.1 disappeared and 22.5 came in. Also outside temp re-appeared above steering wheel.

22.5 Compressor re-engagement circuit, VAG 1551 Scan Tool function

Does this mean that I need to reset the above with VAG-COM or go to dealership, after that it should start to work. I hope.

Funny. I never posted my solution. I decided to replace the relay & while under the dash I found the connector was loose at one end. This explained why it worked each morning & as it became warmer the plastic plug expanded just enough to break the contact.
SO if you have intermittent A/C CHECK ALL THE CONNECTIONS

[Samppa]

Funny thing, I just went for a drive and 22.5 has disappeared but compressor still wont start. Still having these codes:

02.3 Interior Temperature Sensor, in Headliner, sporadic open
03.3 Interior Temperature Sensor, in Instrument Panel, sporadic open
05.3 Outside Air (Ambient) Temperature Sensor, front, sporadic open
06.3 Engine Coolant Temperature (ECT), A/C sporadic open

I can read values for these via climate control unit so they should be just fine.. Any ideas ?

[veneto rs2]

Check your multifuncion switch. This is the large brass one on the water outlet on the head. I have seen this switch cause A/C problems before. The newer switches come with three pins instead of the original four. This extra pin was for A/C cutout circut. Faulty MFS sometimes can cause intermittant function.

I second that.

If you have the four pins old version of the "multifuzzi" (that's what the Germans call it) a simple and easy way of checking it out it's loosing one pin per time.
If you find that by loosing one of them the AC kicks in.... then you have the solution.

One of the pins was ment to be protection when the motor coolant gets over a certain temp hence it stops first thing the AC.
I had problem with this sensor a couple of times with my S2 3B eventually after changing a couple of them (they cost a gunshot of money!) I just went for let the wire loose and keep an eye at the temp gauge... (wich i always do AC or not AC)

Stefano

[alg]

I second that.

If you have the four pins old version of the "multifuzzi" (that's what the Germans call it) a simple and easy way of checking it out it's loosing one pin per time.
If you find that by loosing one of them the AC kicks in.... then you have the solution.

One of the pins was ment to be protection when the motor coolant gets over a certain temp hence it stops first thing the AC.
I had problem with this sensor a couple of times with my S2 3B eventually after changing a couple of them (they cost a gunshot of money!) I just went for let the wire loose and keep an eye at the temp gauge... (wich i always do AC or not AC)

Stefano

Funny when I disconnected mine the A/C worked

[Samppa]

Ok, problem solved, almost Before I only checked fault codes from channel 01c. But when i checked channel 52, I saw low pressure fault. So system is leaking but at least now after refill it's working as it should.