[zaiddroid]

I own a 2008 Skoda Fabia, and recently I've been experiencing an issue with the AC. It cools fine for about 30 minutes, but then the cooling stops, although the fan keeps blowing air. To get it working again, I have to turn the car off and on.

I visited a local AC technician who thought the issue was with the compressor wall, the high-pressure switch, and the water pump (since he noticed the engine was running hot). I replaced all of these parts, but the problem persisted. While replacing the compressor wall, I noticed a black oil-like substance leaking from the compressor. However, the technician assured me that if the compressor or condenser were the problem, the cooling wouldn't work at all, not even for the first 30 minutes. We also tried removing and reinserting the same evap sensor below the steering wheel and noticed that the pipes were getting frozen when removed and the ice melted when inserted.

I then took the car to a different technician, who tested the power supply to the compressor by attaching a light bulb to the compressor wire. After about 30 minutes, the light went out, indicating the power was being cut off. When the car was restarted, the light and the AC came back on. He was certain that the issue was electrical, not with the compressor or the AC system itself, since the cooling would restart once the power was restored.

We scanned the car, and the only error that came up was related to the drive battery voltage ("implausible signal"), which the technician said wasn’t related to the AC issue. He ran tests on various car modules, and while checking, the wipers activated randomly, and the AC started cooling again, only to stop after 30 minutes as usual. Despite the tests, no significant errors appeared, except for the battery voltage issue.

The technician now believes the problem lies with the Body Control Module (BCM) and suggests it needs replacing. I'm unsure if this is the real issue, especially since I initially thought the black oil in the compressor indicated a fault with the compressor or condenser. Could it be the BCM, or is there another potential cause? I’d appreciate any advice. Please help. Thanks

[audioholic]

Please dig deeper with the diagnostic tool and if possible go with a VW specific tool like VCDS, OBD11 Etc. This is a systematic cutoff which could happen due to various reasons. These reasons and the status of the compressor can be read via measuring values in the ECM and Climate modules. Sometimes the ECM can request compressor to be cut due to reasons like Torque demand, Temperature etc or it can be also something like a faulty outside temperature sensor. This can be clearly observed via advanced measuring values. I would only touch the hardware like compressor only if the diagnostics report that the compressor is triggered but it wont run. Normally there wont be an error seen if the compressor shut off is due to natural reasons such as low outside temperature, low evaporator temperature etc. Only diagnostics can tell this story.

[zaiddroid]

Thank you so much audioholic for your comment. I think you are right, only after being certain with a diagnostic tool like vcds can we proceed ahead to really diagnose the issue. Only after the issue is confirmed we can make changes to the hardware. However, I’m not very knowledgeable in this field and I stay in Bangalore, India too. Can you help me with it, if you can? We could scan using vcds. I’m not very knowledgeable in this niche. Please help. Thanks

[audioholic]

Originally Posted by zaiddroid

Thank you so audioholic. You are right. We gotta we sure before we oroceed with a vcds diagnostic tool. Are you from bangalore as well? Can you helo me? I’m not very knowledgeable in this niche. Please help. Thanks

Unfortunately I dont have the time or space to do this. There are plenty of competent garages with good tools which they can use to both diagnose faults and do the necessary work. So do check with some recommendations on TBHP or elsewhere. This is not something the conventional auto mechanic/electrician can diagnose.

[zaiddroid]

You are right a conventional garage/technician cant solve this. If you have any personal recommendation in Bangalore that you trust for your car, please let me know. I would be grateful. Thanks a lot for your advice. Someone recommended me automobile exponential in whitefield, but if you can vouch for them or suggest your own recommendation it would be great. Thanks

[mercedised]

Get it checked at Skoda authorized service center, let them diagnose the issue. They will tell you the actual problem which you can then get rectified from outside if budget is an issue.

[anujmishra]

Originally Posted by zaiddroid

I own a 2008 Skoda Fabia...

removing and reinserting the same evap sensor below the steering wheel and noticed that the pipes were getting frozen when removed and the ice melted when inserted.

I think the AC thermostat gone bad. In most of the cases it is fixed inside dashboard. Due to this the evap coil get frozen with ice and cooling stops.

My previous car also had similar issue and I was managing periodically swithing off and on the AC.

[zaiddroid]

If the thermostat was the problem, when I removed the thermostat ice was formed and when I reinserted it, the ice melted. So that means the thermostat is fine right? Also shouldn’t the scan show the error of thermostat?

Hey @mercedized, the Skoda showroom denies to check as the compressor is an outsider manufactured compressor which I had changed 2 years back. They suggest to replace the compressor and wiring (they don't even accept joints in wires, they recommend new wiring altogether)

[ninjatalli]

Originally Posted by zaiddroid

You are right a conventional garage/technician cant solve this. If you have any personal recommendation in Bangalore that you trust for your car, please let me know. I would be grateful. Thanks a lot for your advice. Someone recommended me automobile exponential in whitefield, but if you can vouch for them or suggest your own recommendation it would be great. Thanks

Go through garages based threads in the Bangalore section and you'll get options that are recommended by bhpians based on their experiences.

EE (Engineering Exponent, Whitefield) is probably the garage recommendation you got. If so, they do have quite a good reputation / feedback in Bangalore.

[AMG Power]

Originally Posted by zaiddroid

So that means the thermostat is fine right? Also shouldn’t the scan show the error of thermostat?

The only way to confirm if the thermostat is gone to fit another one (a spare) and see if there is a difference.

The VCDS will only show a generic fault with the HVAC system. Isolation of the fault to check whether it is the thermostat will have to be as above.

[zaiddroid]

Originally Posted by ninjatalli

Go through garages based threads in the Bangalore section and you'll get options that are recommended by bhpians based on their experiences.

EE (Engineering Exponent, Whitefield) is probably the garage recommendation you got. If so, they do have quite a good reputation / feedback in Bangalore.

I connected with engineering exponent and they said that they don’t deal with Ac issues. They just work with coding and upgrades.

[sumeethaldankar]

Had a Civic where the a/c would stop to work after driving sometime. It was diagnosed to the a/c relay in the fuse box. It was changed and the problem went away.

[zaiddroid]

oh ok nice, Ill get the relay checked again. Thanks

[svsantosh]

Try united motors Rajajinagar (Bosch Authorised) near Magadi road toll gate. They are the 2nd best to any A.S.S because they have access to all brands manuals and laptop and scanners.

Skoda AC issue is not as simple as a condensor leak or compressor going weak. Get a laptop + knowledgeable AC mechanic to check the car.

You spoke of changing the Pressure switch that sticks into the compressor, but did you also change the Expansion valve (mostly seen in the firewall between the cabin and engine area?) Please advice. If that is also done then it is the electronics fooling the compressor to cut off.

The compressor diagnostic is pretty simple, the mechanic needs to hardwire/short a test lamp from compressor power to the inside of the car, when the AC clutch is engaged the light will be on, if compressor/clutch is getting cut off at the 30 min mark, then you can pin point the issue. Was this tried?

[zaiddroid]

Originally Posted by sumeethaldankar

Had a Civic where the a/c would stop to work after driving sometime. It was diagnosed to the a/c relay in the fuse box. It was changed and the problem went away.

Originally Posted by AMG Power

The only way to confirm if the thermostat is gone to fit another one (a spare) and see if there is a difference.

The VCDS will only show a generic fault with the HVAC system. Isolation of the fault to check whether it is the thermostat will have to be as above.

Just to confirm, by a thermostat do you mean an evaporator sensor? Where exactly is this located, please guide. Thanks

Originally Posted by svsantosh

Try united motors Rajajinagar (Bosch Authorised) near Magadi road toll gate. They are the 2nd best to any A.S.S because they have access to all brands manuals and laptop and scanners.

Skoda AC issue is not as simple as a condensor leak or compressor going weak. Get a laptop + knowledgeable AC mechanic to check the car.

You spoke of changing the Pressure switch that sticks into the compressor, but did you also change the Expansion valve (mostly seen in the firewall between the cabin and engine area?) Please advice. If that is also done then it is the electronics fooling the compressor to cut off.

The compressor diagnostic is pretty simple, the mechanic needs to hardwire/short a test lamp from compressor power to the inside of the car, when the AC clutch is engaged the light will be on, if compressor/clutch is getting cut off at the 30 min mark, then you can pin point the issue. Was this tried?

Hey I'll definitely try united motors if they have vcds system to diagnose a skoda/VW car. You are right a knowledgeable person is needed with a greater laptop scanner. The pressure valve inside the compressor was changed. The expansion valve, I have no idea where it comes. High-pressure switch in the front engine bay was changed as well.