C350CDI engine fan comes on straightaway

[Dankewell]

Hi everyone,

Just got a quick question, my engine fan comes on within about 10 seconds of the engine turning on. Engine temp is a constant 90 degrees, Any ideas what it could be?

 

[MrGreedy]

Is this even when the car engine and coolant temperature is low. If so, it could be low air con pressure. I've just had this. I'm waiting for an air con pipe, as whilst it was the condenser that had a leak, the short pipe that connects between the compressor and the bottom of the condenser had welded itself on with corrosion. Even leaving the bolt soaked over night with penetrating fluid (not WD40), I ended up (very easily) snapping the head off the bolt. Such a pain.
Now FedEx have lost the pipe which was sent by Mercedes Grangemouth last week.

 

[Dankewell]

Is this even when the car engine and coolant temperature is low. If so, it could be low air con pressure. I've just had this. I'm waiting for an air con pipe, as whilst it was the condenser that had a leak, the short pipe that connects between the compressor and the bottom of the condenser had welded itself on with corrosion. Even leaving the bolt soaked over night with penetrating fluid (not WD40), I ended up (very easily) snapping the head off the bolt. Such a pain.
Now FedEx have lost the pipe which was sent by Mercedes Grangemouth last week.

Yep even when engine is cold, good shout cos I tries the air con last week and it wasnt cold at all, might get it re gassed see if that fixes it

 

[MrGreedy]

If the car is an older model (i.e. more thsn 4 or 5 years old) by all means get the car regassed. If it passes a nitrogen pressure test, they regas and this fixes it, I would also them get booked in for an aircon fault check/inspection by a good independent aircon specialist, and ask them to see if they can find a leak very slow leak not identified by the pressure test. This is often most easily identified by PAG oil showing a leak somewhere, or by the presence of UV dye leaking out.
Make sure you get UV dye added as part of the regas.
Probably best to use the same aircon specialist for the whole thing.
You might find if they regas, then a few days later degas as part of the fault finding, you might save some money because they will 'weigh in' any gas recovered as part of the degas and knock that off you 2nd regas bill if they have found a leak that needs to be fixed.

If there is a leak, you will be losing oil as well as gas, and running the aircon without enough oil will damage the compressor. A specialist will need to take an educated guess about how much oil to put back in.

Most common failure points:
Hole in condenser.
Leak on compressor shaft seal.

 

[Dankewell]

Thanks for the info will try and get that booked in, hopefully it fixes the issue