Board logo

Trying to Sort the Lads Corsa Air con.
karlak - 7/6/15 at 08:59 PM

I have finally got round to looking at my sons Corsa Sxi 06 plate (c model) which the air con has never worked since we bought it a while ago.

I got the system recharged which made no difference, the compressor centre clutch part won't spin when the air con button is pressed. So, had a look at it today with a Sealey electrical tester. While doing this I noticed the positive lead to the connector on the compressor had broken, happy days, or so I thought.... Repaired the break and popped it back together, but still the compressor isn't engaging.

However, if I use the electrical tester and put 12 volts into the connector to the compressor, it spins up and apparently (son sat in the car) starts cooling the air, so that discounts the compressor as being broken I assume.


I also see there is a Fuse 31 for the Air con system. I have checked this and it is fine.

So to summarise, I don't seem to be getting 12 volts to the compressor connector, but if I "force" 12 volts into the compressor, then the compressor will spin. I am off to find the Haynes manual as I presume there will be a coolant pressure switch somewhere, hopefully there is a way I can test that. Although, I seem to remember form looking before, the Haynes manual is very sketchy about the air con system.

Looks like there is a pressure sensor/switch, located in a bloody awful position to get to easily. It may have a 3 pin connector from some research, so hopefully if I can get the connector off and "short" out the pins, perhaps the compressor will kick in.

Any other ideas ? or am I on the right track....

britishtrident - 7/6/15 at 09:29 PM

The switch is the trinary switch, it has two functions to switch the cooling fan on when the compressor is on and pumping the pressure and to act as an over pressure safety cut off working via the ecu which disconnects the AC compressor clutch when the safe Max pressure is exceeded.

The fuse concerned is fuse 31 and the relay is K5 start by checking the fuse and relay.


[Edited on 7/6/15 by britishtrident]

karlak - 7/6/15 at 10:25 PM

quote:
Originally posted by britishtrident
The switch is the trinary switch, it has two functions to switch the cooling fan on when the compressor is on and pumping the pressure and to act as an over pressure safety cut off working via the ecu which disconnects the AC compressor clutch when the safe Max pressure is exceeded.

The fuse concerned is fuse 31 and the relay is K5 start by checking the fuse and relay.


[Edited on 7/6/15 by britishtrident]


Cheers

I have checked the fuse 31 and it is fine.

I was wondering if there was a relay driving it. The Corsa handbook and the Haynes manaul is pretty hopeless. It talks about a relay K49, but does'nt mention where it is located and I am not even sure that it is Air con related, more to do with rear screen heater by the looks of the wiring diagram.

Do you have any idea where K5 is actually located ? Apart from getting a new Relay and trying it, can I use the Sealey voltage tester I have to check the relay ? I guess I could remove the relay and and apply 12 volt down the correct pin/socket.

Ninehigh - 8/6/15 at 01:12 AM

Before you start going mad with testers and relays, could it be the switch in the dashboard?

karlak - 8/6/15 at 02:54 AM

quote:
Originally posted by Ninehigh
Before you start going mad with testers and relays, could it be the switch in the dashboard?


Pretty sure that the dash switch is fine.. We get the LED lit and a slight change in revs when pressed.

britishtrident - 8/6/15 at 05:40 AM

Check the small black relay bottom row 2 from left of the fuse box
Pretty sure it is the same as a Rover 75 fuel pump relay.

I have one of these http://www.maplin.co.uk/p/maplin-automotive-relay-tester-a19qx only cost a £10 from Maplin

MP3C - 8/6/15 at 10:01 AM

I don't know if it is related or not, but might be worth a try. I was trying to get my air con working on my fiesta as the clutch would not spin and no aircon but when I went to get it refilled it said it was full. However after getting new compressor (didn't fit in the end), relay and everything the problem was that the air con was such low pressure, the clutch wasn't engaging and as such wasn't allowing the coolant to flow when it was being filled. I tripped the relay to enable the clutch on the compressor and got one of those refill cans from halfords and it filled up. Once it got to a certain pressure, it stayed on fine and works as normal now.

Might be something different but might help.

Matt

karlak - 8/6/15 at 10:39 AM

OK,

So, I popped 12 volts into the fuse box where the relay sits and the compressor spins up. The Relay is switching when I put 12v on to it and swapped with the low beam relay anyway, but still not working.

So it is something that is stopping the activation voltage getting to the relay when I press the air con button in the car. I am thinking it is the pressure switch, or perhaps the regas hasn't worked properly... I may run it back down the garage who gassed it when i get a chance, to double check.

Getting to the pressure switch looks a right pain

[Edited on 8/6/15 by karlak]

DW100 - 8/6/15 at 11:26 AM

Ok so the diagram I have shows the K143 relay powered from fuse 31 and activated by the engine ECU grounding pin 85

The "switch" is actually a pressure sensor and should be readable in ECU live data.

[Edited on 8/6/15 by DW100]

karlak - 8/6/15 at 01:46 PM

quote:
Originally posted by DW100
Ok so the diagram I have shows the K143 relay powered from fuse 31 and activated by the engine ECU grounding pin 85

The "switch" is actually a pressure sensor and should be readable in ECU live data.

[Edited on 8/6/15 by DW100]


Have no way of reading the ECU live data

My theory is that when I apply 12 volts where the Relay would be in the fuse box, the compressor kicks in, I would have thought that this in itself would only allow the compressor to spin if the pressure sensor/switch was in a "good" state ?

I am trying to find a wiring diagram that shows how the sensor is related to the compressor. eg. is it just an inline switch, if so, then it must be OK as the compressor will spin, when 12 volts is applied at the fuse/relay box.

I am starting to wonder about the actual dashboard aircon button in the car now.. Its LED does light, but then I guess that does not guarantee the button is actually activating.

DW100 - 8/6/15 at 02:57 PM

The Air con pressure sensor is an input to the Engine ECU. When it is happy the ECU grounds the control wire to the relay switching on the compressor clutch.

You can test the output of the sensor with a multi meter. You should have 3 wires, +5v, ground and a signal. Signal will be 0.5 to 4.5V proportional to pressure.

karlak - 9/6/15 at 11:52 AM

A bit of an update.

I found how to check the Corsa for error codes. - Pedal pressing while putting ignition on... and get this.

P1530 A/C Relay Voltage High Air Conditioning System B-10
P1530 A/C Relay Circuit Open Air Conditioning System B-10


Which I guess is good as it points to the problem I have. Also doesn't pick up code for a pressure problem, which discounts the pressure sensor hopefully, which is good, because I cant get to that to check anyway.

DW100 - 9/6/15 at 12:30 PM

Those look like faults you have caused by removing the relay whilst testing.

Clear them and see if they come back.

karlak - 9/6/15 at 12:32 PM

Doh!!! of course..

I guess I will need an OBD device to clear the codes..

karlak - 11/6/15 at 06:51 AM

Thanks for your help guys with this.

Still not fixed as I have had to leave it for now as he is using the car to get to School for his A-level exams. Last thing I want to do is break something else and leave the car unusable.....


So, I am thinking the problem is the Air con Pressure switch, which looks like a 3pin "transducer" type and have now found where it is located . I was wondering if anyone has replaced one of these ? It seems some of these pressure sensor/switches can be replaced without de-gassing etc. They screw into a valve which will keep the system sealed when the sensor is unscrewed. I am just struggling to find any information about the Corsa C '06 model about this, which is really weird as it is a very common car.

==========

Also, as an aside. I borrowed a bluetooth OBD reader and had a quick look at what was going on. No faults are logged at all (the two previous AC RElay ones have cleared themselves). But, what I did find is that the coolant temp was showing very high, the car had just been started and it was reporting over 120 deg C. The normal dash gauge seems fine - need to double check though. I did think the OBD reader/software could be screwy, but have had that checked by trying it on a friends Corsa (same model) and that showed the coolant sensor reporting as expected,

I cant understand how it could be reporting 120 deg C and yet the gauge in the car was not off the scale.

britishtrident - 11/6/15 at 11:52 AM

Sounds like the coolant temperature sensor or the wiring to it is the cause of the AC fault On modern cars the temperature gauge is driven by the ECU, if the ECU isn't getting a signal from the coolant temperature sensor or the signal is out of the expected range compared to other engine sensors the ecu will drive the gauge to "N" .



[Edited on 11/6/15 by britishtrident]