75ZT Community

[Ed3]

On my 06 reg CDTi it was pointed out at the Nano that my Air Con Condenser has failed and there are lots and lost of bits falling off it.

I now have a strange noise when driving that I wonder if it could be a kind of wind noise on the air con condenser? The noise is a bit like what some of us may imagine a diff and gearbox could be like if no oil - but the sound is louder than a gearbox with no oil. If I coast in neutral the noise does not seem engine related. If I switch the engine off while travelling and coast the noise is there until car speed is below 5 or 10 mph when it is quiet below or 10 mph. I have looked around the drive shafts and front wheels and cant see anything wrong and so wonder if a condenser that is "very much" falling apart, gives a wind noise that is different or unusual?

[Arctic]

Sounds like the aircon "whale song" to me, a whoop whoop sound

Next time it happens, press the econ button on the aircon panel.

Quote From TC.

To quote member Ambleson - the whooping sound is from thermal transfer valve (TRV) reacting to the temperature drop in the evaporator. The evaporator is supplied with liquid refrigerant via the TRV and if the temperature in the evaporator is higher than 4°C the TRV opens to allow more gas to evaporate and so cool the unit. The evaporator starts cooling and the TRV detects this and slows down the amount of liquid released. It is this shut down that produces the whooping noise until the equilibrium is reached. The slight hiss you may hear is the liquid refrigerant boiling off in the evaporator. This produces the cooling. Press the 'Econ' button and the hiss will stop. The evaporated gas is then compressed and cooled in the condenser at the front of the car. This stage requires the slow running radiator fan to produce the liquid refrigerant again.

To add to this, the efficiency of the condenser is also important and any insufficiency there will also contribute to the whooping noise. If a simple recharge doesn't resolve the issue, check the condenser. The fins on the matrix are known to disintegrate after several years.

TC

[takestock]

If after trying Arctic's suggestion the sound is still there (I hope it isn't) then it would appear to be speed related as opposed to airflow but not driven by engine speed. That would then lead me to investigate drive shafts, wheels, tyres and bearings. I have had strange noises from tyres in the past that have worn uneven.

[Duncan]

If after trying Arctic's suggestion the sound is still there (I hope it isn't) then it would appear to be speed related as opposed to airflow but not driven by engine speed. That would then lead me to investigate drive shafts, wheels, tyres and bearings. I have had strange noises from tyres in the past that have worn uneven.

I'd add to that, to check for a stone trapped between brake disc and backplate.

[Ed3]

Sorry I dint explain enough. I am kind of in limbo because of rusty sills needing welding which may not be economically viable on a battle scarred workhorse that I paid £600 for 8 years ago. Although the car is an 06 plate it is more rusty from always being in rain places. So I left the air con totally empty with the old condenser on and shedding bits all the time while I work out if I can arrange cheap welding. While the condenser is falling apart I have the wind or scrapping type noise

[Duncan]

If there's no refrigerant (gas) in the system, the aircon system won't run. So it's not the condenser directly. It's kind of possible its the crumbling condenser coming into contact with the back of the cooling fan, but symptoms don't sound at all like that. The suggestions about driveshafts / brakes / wheel bearings are first places to look, I reckon.

[Ed3]

thanks Duncan, I'll get the front end up and turn the wheels by hand. i took a few photos but couldn't see anything.