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[05omegav6]

Got the aircon regassed, but the compressor clutch isn't engaging...

0v going to the compressor, so where to be looking for the culprit

[05omegav6]

Clutch engages when connected direct to battery, aircon working as expected, which is a start

Fuses 12, 14 and 15 ok as well have swapped the relay with both the horn one and K87. No change, all three relays work on the horn circuit, so confident that I have ruled out that problem.

Every thing else (according to the book of blocks) seems to point to the engine ecu or wiring to the relay

[05omegav6]

Might be a coincidence, but the coolant pump on the radiator has just gone up in smoke

When compressor connected direct to battery...

1. Front fans run constantly.
2. Second stage fan in the cabin air intake runs.
3. Main fan cuts in/out as expected from the gauge.

Plug compressor relay in, and 1. and 2. both cut out instantly, 3. stays the same.

What is likely to happen with the clutch permanently engaged, even when engine off?

[Andy B]

... or wiring to the relay

At some point before I owned the car, the wiring underneath my battery had been 'modified' by Vauxhall. I've the receipt for it somewhere.
Any use?     

[05omegav6]

All looks to be in order under there

That looks like I soldered it

Front fans do come on with the compressor off, but only after the rear fan which I believe is normal when aircon off...

[RobG]

Got the aircon regassed, but the compressor clutch isn't engaging...

0v going to the compressor, so where to be looking for the culprit

Faulty low pressure switch

[05omegav6]

Got the aircon regassed, but the compressor clutch isn't engaging...

0v going to the compressor, so where to be looking for the culprit

Faulty low pressure switch

Presumably there are only three things which will tell the ecu not to power the clutch relay...

1. Low pressure.
2. ECO switch on the climate panel.
3. OFF switch on the climate panel.

How reliable are the pressure switches, and are they available separately 

[RobG]

Got the aircon regassed, but the compressor clutch isn't engaging...

0v going to the compressor, so where to be looking for the culprit

Faulty low pressure switch

Presumably there are only three things which will tell the ecu not to power the clutch relay...

1. Low pressure.
2. ECO switch on the climate panel.
3. OFF switch on the climate panel.

How reliable are the pressure switches, and are they available separately 

How long`s a piece of string. Can be obtained separately

[05omegav6]

All the other wiring seems to be behaving as expected. When the clutch is plugged to the battery, the front fans run instantly, and I have disconnected the radiator pump as that's now dead.

Shall try the pressure switch next

Thanks all

[biggriffin]

low pressure switches are available but cost £58.+ on tc, hence i got a s/hand one from scrappie £2.00.

[05omegav6]

 

Presumably the system will need regassing again

[RobG]

Presumably the system will need regassing again

Depends how quick you are with a spanner

[05omegav6]

 
Might only make a small hole in the Ozone layer if I remember to unplug it first

[Andy B]

Might only make a small hole in the Ozone layer if I remember to unplug it first

If the a/c specialist is going to re-gas your system afterwards, they'll normally de-gas it for you for free.

[05omegav6]

I try to keep things simple... the machine is much quicker if there's nothing to drain out of it

A valid observation though

[Andy B]

... the machine is much quicker if there's nothing to drain out of it
 .....

A good point, well made!       

[biggriffin]

Presumably the system will need regassing again

o yes,have you got your vx masterfit voucher,if so get vx to do it.
or you could go to (time to get linched) halfruds get a a/c kit using your trade card,(omega uses whole tin) refill with that to check system is working,(take empty back £10 back).

[sassanach]

I not sure on the ohmygod,but on vectras of the same period you can change the low/high pressure switch's without emptying the system.

[05omegav6]

Shall investigate some more at the weekend

[Kevin Wood]

Before you change anything, try diagnosing the pressure switch (aka triple switch) by bridging the contacts.

From memory, the aircon triple switch is fed a signal from the climate panel which enables air con if the climate panel is calling for cold air. It will break this circuit if the system pressure is below the minimum pressure or above maximum pressure. This wire is colour coded black with a white tracer at the triple switch.

This signal then feeds an input to the engine ECU. If you've got a code reader that shows live data I believe you can read the level of this input from the ECU. Output from the engine ECU feeds the air conditioning relay K60 so the engine ECU can veto the use of air con in certain cnditions.

There is also a coolant temperature switch that breaks the ground connection to the air con compressor if the coolant gets too hot. This would leave the fans operating as normal, so guessing this isn't the problem.

The triple switch also has another contact (Brown / Brown with white tracer) which brings the fans up to full speed at a certain pressure.

I would try bridging the black / white wires into and out of the triple switch next.

[Kevin Wood]

By the way, it's also worth checking fuse 29.

EDIT: and fuse 52 in the engine bay fuse box, considering that pump burnt out, although it will only affect engine cooling and not air con.

[05omegav6]

Thank you for that Kevin was thinking along the same lines so that I can refit the relay if nowt else

[albitz]

Well,if you need a compressor.
http://www.ebay.co.uk/itm/330973104057?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

[05omegav6]

Well,if you need a compressor.
http://www.ebay.co.uk/itm/330973104057?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

I don't, but at that price... I might

[biggriffin]

Well,if you need a compressor.
http://www.ebay.co.uk/itm/330973104057?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

If id have seen that would have had a go, new they cost £150.
 missed a bargin there

[05omegav6]

Before you change anything, try diagnosing the pressure switch (aka triple switch) by bridging the contacts.

From memory, the aircon triple switch is fed a signal from the climate panel which enables air con if the climate panel is calling for cold air. It will break this circuit if the system pressure is below the minimum pressure or above maximum pressure. This wire is colour coded black with a white tracer at the triple switch.

This signal then feeds an input to the engine ECU. If you've got a code reader that shows live data I believe you can read the level of this input from the ECU. Output from the engine ECU feeds the air conditioning relay K60 so the engine ECU can veto the use of air con in certain cnditions.

There is also a coolant temperature switch that breaks the ground connection to the air con compressor if the coolant gets too hot. This would leave the fans operating as normal, so guessing this isn't the problem.

The triple switch also has another contact (Brown / Brown with white tracer) which brings the fans up to full speed at a certain pressure.

I would try bridging the black / white wires into and out of the triple switch next.

Tried at the switch end. No joy

Bridging the BrWs wires puts the high speed fan on, but only the drivers' side both front fans run when the clutch is connected directly to the battery, so guess one high speed fan is normal...

Fuses 29 and 52 both fine

[Kevin Wood]

That's weird. I know you can force the ECU output to pull in K60 using a Tech 2. Might be worth a try. I would also try pulling K60 and bridging the pins where its' contacts are. Should enable the compressor clutch and fans.

I think one fan on full speed would be normal in the situation you describe. The other fan requires K60 to be pulled in.

[05omegav6]

Wiring diagram received guess the pressure switch is functioning as expected.

K60 not doing anything so guess an issue with the switching feed to that connect the clutch output to the battery, the front fabs run and clutch engages...

[symes]

not being funny but how is electrical plug connecting air con----mine was smothered in oil and caused all sorts of hassle
and it can chaff through as its near sharp metal

[Kevin Wood]

Wiring diagram received guess the pressure switch is functioning as expected.

K60 not doing anything so guess an issue with the switching feed to that connect the clutch output to the battery, the front fabs run and clutch engages...

K60's feed comes from the engine ECU only a few inches away. What happens if you take the top off K60 and activate the contacts manually?

[05omegav6]

Nothing

Just to add in response to Symes, compressor connection fine currently running it with 12v feed from battery direct to clutch output of the relay holder

[Kevin Wood]

Nothing

That's odd

Do you have 12V at pin 30 and 86 of the relay base with the ignition on?

Forgot to say, if you're going to manually operate the relay contacts, ignition needs to be on.

[05omegav6]

Had guessed that much

Nothing between 86 and 30, but my multimeter might be defunct doesn't register a voltage across the battery, let alone a relay

[Andy B]

..., but my multimeter might be defunct doesn't register a voltage across the battery, let alone a relay

Ooops!     

[Kevin Wood]

Had guessed that much

Nothing between 86 and 30, but my multimeter might be defunct doesn't register a voltage across the battery, let alone a relay

Have you been using the Amps range and fubared the internal fuse?

Anyway, I was talking about between 86 / 30 and ground. There'll be nothing between them but they should both get an ignition switched feed.

[05omegav6]

Can connect all four terminals together, engine running and nothing happens

[Kevin Wood]

Can connect all four terminals together, engine running and nothing happens

Ok.. But if you connect pin 86 to 12V the compressor and fans kick in?

Are you sure F29 is OK?

[05omegav6]

Yes to both

[05omegav6]

Right progress of sorts

Now if I connect sockets 30 and 87 together, with no relay, the aircon clutch engages, and the fans run when the ignition is switched on. Switch off, all goes off  which means I no longer need the direct connection to the battery

Relay in and nothing happens

Have yet to try another relay, but previously they all tested working in the horn circuit...