Monday, February 04, 2013

That dam fan

Right the weather was good again today so after studying the electrical diagrams to the Skoda Superb’s Air Con system I got the bumper off again. Today I was looking for the air con pressure switch.

Right with the bumper off here is the blighter. You still can’t get at it though without further dismantling.

Well I can’t get the camera up there either.

But with my magic mechanic hands I did manage to get my fingers in places they should be and got the plug out of the socket. With the plug removed the fan stopped like it should. I then linked two of the terminals and the fan came on slowly like it should. I then linked the other two terminals and the fan ran at full speed. So its probably faulty even though it has not registered on the Vag com. So it will be ordered. Anways here's an overview of how the system works the fan.

The climate control unit in the car.

The air con system control unit J314.

Air con pressure switch F129 and Radiator Fan Control Relay J26

The radiator coolant sensor F18, The radiator fan V7 the high speed realy J280 the low speed realy J279 The Fan Run On Relay J397

System overview

This is the page with the fan shown item V7. The fan has two speeds of operation slow and fast.

The two speeds are controlled by relays J280 for fast and J279 for slow.

For slow speed relay J279 needs to be energised. This is done by:

The coolant temp sensors F18 stage 1 near the radiator or the The Radiator fan control relay J26 being energised.

The fan can also run in slow mode via relay J397 – the radiator fan run on relay, which keeps the fan going when the engine isn’t running but a temperature sensor F38 is seeing hot temp..

Fan control relay J26 can be energised by:

The air con switch E35 in the climate control unit or the air con pressure switch 1 F129 to signal there is sufficient pressure in the air con to allow it to run. The power through the air con switch 1 comes from J314 the Air conditioning system control unit (which also brings on the air condition condenser magnetic coupling into action).

For fast fan speed J280 needs to be energised. This can be energised by the following:

The coolant temp sensors F18 stage 2 near the radiator  or the air con pressure switch 2 F129 sensing high pressure.

So here is the diagram of the pressure sensor I intend to swap to see if this gets things working correctly again.

One ponders is the air con gas going to come out?

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