130 radiator fan

[martin sheppard]

Hello Everyone,

First time post for me, I've had four Galaxy's ( two now )

My 130 ghia fan wont come on at all  - vag com, no faults.

Pressure transducer has a square wave output - there's gas in system

compressor comes in and starts to work but but the air con guy said turn it off because the fan isn't working so the pressure will build up and vent the gas?
The fan has 12v and 0v and i've tried three other fans?
does anybody know what the two control wires to the fan do? so I can probe with a scope.

regards Martin

[insanitybeard]

There's a little mention of the fan (first paragraph) setup on the 130/ 150ps models in this article here, the upshot is that unlike the other models, the 130 and 150ps TDI's (with the large single fan) have fans that are controlled by the main engine management ECU.

Regarding the air conditioning, I thought that normally the system is designed to not work if the fan isn't working, so although the compressor might cut in briefly, if the fan isn't working, it should quickly disengage. Is this not the case?

So are you saying you have a 12v feed to the fan motor and a good earth but it still isn't working?

[martin sheppard]

Hello

there is a good supply present (when the compressor runs)

My worry is that the air con bod said that the compressor has a safety relief that would vent the newly paid for gas

The fan motors have six triacs/ transistors in them I assume to energize the coil winding's in sequence.

I wonder if the two small cables might be a safety signal or a "run fan at ** speed signal".

[johnnyroper]

The system won't dump its refrigerant if fan not running,the high pressure switch will open due to excessive condenser temp and switch compressor off.
How many wires go to the fan?

[johnnyroper]

Sorry just re read your first post the 2 wires will be control from engine ecu to switch the fan on. Fans have a live and earth present but ecu sends signal to switch on depending on coolant temp or air con operation. I would think it is a varying voltage to vary speed of the fan.

Does yours have a temp switch in rad? If so does the fan run if it is bridged?
Have you checked the basics like fuses?

[johnnyroper]

Don't know if this will be of any use but it shows the control system for air con,the cooling fan will be activated by the output to PCM from pressure transducer and then PCM sends signal to fans.
If transducer is sending signal out then I would be looking at wiring to/from PCM or the PCM itself being at fault.

i know these engines take some heating up but have you had the fan running to cool engine or is it not running for either?

[martin sheppard]

Thanks for the info, just got back in

rad does have switch - bridge it, no fan
when we first tried it the air con guy still had gauges connected and the pressure went straight up to 140 bhp +

he said stop, if it wont vent the pressure the i can test more -

you say wiring to pcm, where do i find that?

thanks for the help - I wondered if the fan kicks in and out when needed  so i might be working anyway?

Theres not much info about the 130/150 aircon stuff

[johnnyroper]

Thinking about it vw thermo switches I believe are normally closed and open when cooling fan is demanded? So theoretically with it disconnected it should run by default?

As it does not work with air con or engine temp I would be looking at PCM and wiring especially as you have tried a different fan.

I think the PCM and other control units related are within the car behind dash engine one requires instrument cluster removal to access.

[insanitybeard]

PCM on mine is behind the battery and to the right of the coolant expansion bottle, next to the nearside wing.

[attachimg=1]

[martin sheppard]

I remember now i have probed around that clutch control relay job in the fusebox, the square wave output signal does appear on that relay.

That being said, there is a output signal from that relay to the pcm where ever that is?

The plot thickens...if only we new what signal was supposed to be on those two control wires on the fan I could work backwards

[martin sheppard]

is it the big alloy case job, looks like an ecu?

[insanitybeard]

Added image to previous post ^

[johnnyroper]

Are you saying pressure went straight to 140psi when turned on?

If it has no fan it would take a while to heat return refrigerant and condenser enough to cause that much pressure. Have you got rear air con? If not I would suspect he has filled with 1100ish grams as per rear air con rather than 740 for front only.

Yes your right my mistake PCM is by battery don't know what one I am thinking of behind clocks.
Mark 1 was behind clocks I had to change one in my mates old sharan that's the reason for my confusion!

[martin sheppard]

it has dual climate control but no vents in the roof, there are two weights 750/1150 on the plate

if it has been over pressured would this be an issue?

[johnnyroper]

Yes if filled to the higher weight you would have instant HP so pressure transducer would shut it down fairly quickly. There's not much else that can cause such a high pressure so soon after turning on,I don't even think a compressor would cause they they usually cause low or equal pressures.

[martin sheppard]

So if the gas won't get vented I could call for air con and see if the clutch drops back out after a while. Do think vag com would see an over pressure code?

[johnnyroper]

I would expect vagcom to see high pressure code as it sees low pressure I think?
Personally as it went straight up to 140 I wouldn't try that as it could damage compressor,the high pressure switch will be set below that to protect the system.

[martin sheppard]

I'll check wiring from fan plug back too pcm and go from there

[johnnyroper]

I would get in touch with air con man see what he filled with, generally want to see about 90psi when first turning comp on before it settles down to 40-50 once it's been running.

[martin sheppard]

I've just re-read my post's -bhp! - psi

great help thank you

why are they classed as dual climate if the cold air only comes from the front cabin?

[insanitybeard]

The rear blower box on the more basic models does blow cool (i.e, ambient temp) air as well as warm, but there isn't a rear air conditioning circuit or evaporator matrix within the rear blower box to cool the air below ambient air temp.

[martin sheppard]

thanks for all your help, I'll up date the post as it goes

Beer o clock me thinks

[johnnyroper]

I don't think it is classed as dual climate unless it has rear aswell or on some cars driver and front passenger have seperate temp controls?

[martin sheppard]

second hand fan fitted and its started to work

THe fan doesn't come on straight away after about 15 seconds

it starts slow and speeds up.

Now that I have a working system at the weekend I will put a scope on the control signals to see what happens.