Technical P0480 and T7 relay

[grapeman]

Hi all,

Had the aircon charged a couple of days ago but there's a further fault. I'm currently trying to fault diagnosis. When ac is on the cooling fan doesn't turn on with it. So naturally I've checked all the relevant fuses and now come to the relays. Im looking for relay T7 but all the ones on top are everything but T7. (Attached a couple of pics showing my box and cover showing their locations)

The only unlabelled relay is the big fat 50 amper in the middle - is this T7?


Extra info: odb reports P0480 so I think this confims my current thinking.

Any help would be appreciated!

Many thanks,
Jon

 

[a1ant]

Hi mate,

T7 is indeed the big relay in the middle. Its Hi side supply comes from the F7 fuse above it.

The fan wont necessarily come on instantly when the air-con is switched on, it cycles depending on temperature.

What engine are we referring to? And what exactly is the fault your having? other than just the error code.

Can you perform actuation tests on your diagnostics kit (MES?)

Alan

 

[grapeman]

Hi mate,

T7 is indeed the big relay in the middle. Its Hi side supply comes from the F7 fuse above it.

The fan wont necessarily come on instantly when the air-con is switched on, it cycles depending on temperature.

What engine are we referring to? And what exactly is the fault your having? other than just the error code.

Can you perform actuation tests on your diagnostics kit (MES?)

Alan

Hi Alan,

Thanks for the reply. I don't have multiecuscan so can't perform any actuation tests - I'm using torque on my mobile.

The engine is a 1.2 16V. (2001 HLX model)

My problem is that the clutch and fan don't come on when AC is turned on. I was looking to see if the relay feeding the cooling fan had a fault off the back of the OBD fault code.

The fault could also be coming from the pressure switch on top of the receiver drier. I had a quick probe of the wire (brown/blue) between the pressure switch and thermostate and found it to be sat at 12V - had to pack away before going any further though so haven't yet decided if that's where it should be. The other wires feed into the engine management - according the Haynes.

 

[a1ant]

Hi mate,

Yeah your looking in all the right places If you check to see if you have power at the compressor electro magnet, it will help you to rule out the 4 way pressure switch or the temp sensor on the condenser.

It's also worth checking f19 which is the direct supply to the compressor electro magnet.

Of course I'm assuming that when you had the system re gassed they checked it for leaks and that the pressure was within parameters.

Alan

 

[grapeman]

Hi Alan,

Thank you for your help!

When it's next dry I'll take a look at what you've suggested and report back.

The aircon guy did do a vacuum hold test before charging so should be leak free.

Jon

 

[grapeman]

Hi Alan,

Had another look today. Here's what I found:

Fuse 19 and the relays R9 and R5 are working as they should (found pin 30 and 87 are the opposite way around but doesn't electrically change anything). I've written the voltages I saw when turned off and relays unplugged and what they went to when plugged back in and turned on. R9 comes on and works fine however the engine managment line is seeming floating for R5 (sits at approx 3V) so does not turn on. I bridged pins 87 and 30 on R5 and the compressor starts up as you can hear in this video: https://www.dropbox.com/s/sznipdxogyibr6n/2014-08-10 19.07.42.mp4

The line between the pressure switch pin 2 (labeled 91) and thermostat pin 2 (labeled 92) is sat at 12V so would suggest the pressure switch has not turned on as you would expect this to be 0 from the diagram. I don't want to manually ground it out though as I'm not sure if this is a floating (open) 12V or if I'd be driving 12V from the thermostat into ground - obviously bad.

Not sure what to do next - any suggestions?

Many thanks,

Jon

 

[grapeman]

Just read this thread: https://www.fiatforum.com/punto-ii/343604-punto-air-con.html

Can anyone confirm that when the pressure switch detects a low pressure it stays off regardless to the pressure returning from a regas?

If so, can I reset it or do I need a new one?

 

[a1ant]

Hi mate,

The pressure switch does not need re- setting after re-gassing. It deactivates the compressor if the pressure is below 2.45 bar or higher than 28 bar.

The 4 stage switch also activates the cooling fan if the coolant pressure is higher than 15bar and the second speed cooling fang if it goes above 20 bar.

Essentially you need continuity between pins 2 and 5 of the pressure switch. This will confirm that a) the pressure is within range and b) the pressure switch is allowing the compressor to engage.

Just to confirm also, that when the fan control knob is pressed, you are getting a yellow light in the centre?

I'll just add- don't forget this is potentially a HIGHLY PRESSURISED SYSTEM - therefore be very cautious before undoing anything should you need to!

Alan

 

[grapeman]

Hi mate,

The pressure switch does not need re- setting after re-gassing. It deactivates the compressor if the pressure is below 2.45 bar or higher than 28 bar.

The 4 stage switch also activates the cooling fan if the coolant pressure is higher than 15bar and the second speed cooling fang if it goes above 20 bar.

Essentially you need continuity between pins 2 and 5 of the pressure switch. This will confirm that a) the pressure is within range and b) the pressure switch is allowing the compressor to engage.

Just to confirm also, that when the fan control knob is pressed, you are getting a yellow light in the centre?

I'll just add- don't forget this is potentially a HIGHLY PRESSURISED SYSTEM - therefore be very cautious before undoing anything should you need to!

Alan

Hi Alan,

Thanks for the info on how the pressure switch is working - I was wondering why the need for so many switches in it.

The fan control nob is indeed lighting up when I press it in and going off when pressing it again.

I checked between pins 2 and 5 and found no continuity between them. Pin 2 is sat at 12V (from the thermostat) and pin 5 is set to 0V (from the engine management). I would expect pin 2 to be 0V. Is the 12V I see from the thermostat a result of a floating to rail or is the thermostat driving it? I'm just wary of grounding 12V lines for obvious reasons.

Do you think I need a new pressure switch, or is there something else causing this [FONT=&quot]behaviour[/FONT]? If I do need a new one, I assume I best take it back to the aircon guy to be fitted because of the risk of pressurised aircon fluid spraying everywhere - is that fair to say?

Many thanks for the continued help!

Jon

 

[PuntoHowTo]

Do you still have a cooling fan error? The cars ecu has the ultimate decision to activate the aircon compressor clutch if errors exist it may simply be the ecu is saying no to the demand for aircon

 

[grapeman]

Do you still have a cooling fan error? The cars ecu has the ultimate decision to activate the aircon compressor clutch if errors exist it may simply be the ecu is saying no to the demand for aircon

Hi Andy,

Yes I do still have an active fault for the cooling fan (P0480). Have you any clues as to how I can look at the desions the ecu is making? Can Multiecuscan give me a better picture than just an obd reader to torque mobile app?

Thanks!

Jon

 

[s and b]

hi
i wont normally get involved in things i dont touch but you seem to be missing the obvious here in that radiator fan not working
now with mes you could actuate this and immediatly try both fan speed settings
so the obvious answer is the rheostat or more commonly the spade connectors on the rheostat on the radiator fan cowling are not allowing a circuit thus stopping aircon from switching in

elementary really

hth

 

[grapeman]

hi
i wont normally get involved in things i dont touch but you seem to be missing the obvious here in that radiator fan not working
now with mes you could actuate this and immediatly try both fan speed settings
so the obvious answer is the rheostat or more commonly the spade connectors on the rheostat on the radiator fan cowling are not allowing a circuit thus stopping aircon from switching in

elementary really

hth

Hi s and b,

Thanks for the reply. I wouldn't say im particularly experienced in car diagnostics so I wouldn't put it passed me overlooking the obvious. I'll try getting some adapters and a copy of mes then

Jon

 

[s and b]

Hi s and b,

Thanks for the reply. I wouldn't say im particularly experienced in car diagnostics so I wouldn't put it passed me overlooking the obvious. I'll try getting some adapters and a copy of mes then

Jon

join the two wires first
see what happens
if you get it working check rheostat for continuity and if good make good new connections

 

[grapeman]

Hi fellas,

Cleaned up the rheostat connections today and manually applied 12v though it to test the connections. The fan spins as it should. The problem has not gone away however. I still have fault P0480 (cooling fan circuit 1) and from probing the circuit found the ecu isn't even trying to turn it on - I wouldn't expect it to seeing as it also isn't enabling the condenser clutch.

I've got a usb obd (with all the different adapters) coming so should be able to do actuator tests soon with mes - will I need a licence or will the free one be ok?

Any other ideas welcomed in the meantime

Cheers,

Jon

 

[grapeman]

Hey all,

Hope you're having a nice Friday!

Probed the lines to/from the pressure switch today (voltages written on attached picture). Do the lines back to the ecu represent a state? E.g. 001 = high pressure, 010 = normal, 100 = low pressure.

Jon

 

[grapeman]

Elm and obd with all the leads arrived today! Got mes on a laptop so ready to go.

Can mes report the current state of the pressure sensor to me? Would be really helpful if I could make sense of its output.

I saw I can run an actuator test on the ac compressor. Isn't this the same as me jamming a wire bridge on the relay pins though?

 

[grapeman]

For the sake of completeness here's a link to a new related thread: https://www.fiatforum.com/punto-ii/355103-ac-thermostat-location.html