Alfa Romeo Forum banner

1 - 20 of 36 Posts

·
Registered
Joined
·
434 Posts
Discussion Starter #1
I have a PH2 spider and air con is not blowing cold air. It was recharged last year and the compressor is working when 12v is fed to it. When air con switch is on, there is no power to the wire which connects to the compressor, so I am now on the hunt for an electrical fault. I have located and checked fuses but can't find relay referred to in workshop manual which is Q22. It says: 'grouped in the engine compartment, next to those of the ignition/injection unit'.

I can find the ignition fuses but no sign of Q22! Does anyone know where it is and are there any other relays/connections I should be checking?
 

·
Registered
Joined
·
434 Posts
Discussion Starter #2
I think I've found it under the o/s engine cover. It is working ok, but no power feeding the coil side when A/C is on. So, I'm now thinking no fliud in the system causing low pressure switch to kick in preventing compressor from running. Thoughts anyone? Thanks.
 

·
Registered
Joined
·
4,627 Posts
I think I've found it under the o/s engine cover. It is working ok, but no power feeding the coil side when A/C is on. So, I'm now thinking no fliud in the system causing low pressure switch to kick in preventing compressor from running. Thoughts anyone? Thanks.
The relay coil should have +12v on it if the ignition key is turned to 'MAR' ( ignition on/car running ). The source ( fuse and maybe relay ) of the +12v varies between years and engine

The other side of the coil is earthed by the engine ECU and will only be earthed if the coolant pressure is OK ( not too high or too low ) and the engine isn't under heavy load.
 

·
Registered
Joined
·
434 Posts
Discussion Starter #4
The relay coil should have +12v on it if the ignition key is turned to 'MAR' ( ignition on/car running ). The source ( fuse and maybe relay ) of the +12v varies between years and engine

The other side of the coil is earthed by the engine ECU and will only be earthed if the coolant pressure is OK ( not too high or too low ) and the engine isn't under heavy load.
Ok, many thanks for the info. There's definately no 12v to the coil. It's a my2000 and CF2. I'm finding the workshop manual a tad confusing with regards to the correct wiring diagram! Is there possibly another relay feeding the compressor relay then? Maybe there is no earth feed as pressure is low (no fluid) and I have lost fluid since last year! Would you see any sign of a leak?

I connected up multi scan and checked compressor clutch again and it is ok.

Thanks.
 

·
Registered
Joined
·
692 Posts
Ok, many thanks for the info. There's definately no 12v to the coil. It's a my2000 and CF2. I'm finding the workshop manual a tad confusing with regards to the correct wiring diagram! Is there possibly another relay feeding the compressor relay then? Maybe there is no earth feed as pressure is low (no fluid) and I have lost fluid since last year! Would you see any sign of a leak?

I connected up multi scan and checked compressor clutch again and it is ok.

Thanks.
You are correct the compressor has a pressure switch so wont come on if the gas is low.
 

·
Registered
Joined
·
4,627 Posts
MY 2000 CF2? Isn't the MY2000 CF3?

You need Vol 3 part 2.

Then select the section for 1998 cars.

Climate control is section 55-26

The first complex wiring diagram is the wiring for the climate ECU. Note the wire saying 'compressor engagement'. That goes to the engine ECU to say switch on the compressor if everything else is OK.

The compressor engagement wiring diagrams start at page 4. They go through 1998, 1999 & 2000 for the different engine types.

For a MY2000 TS ( built after Oct 2000 ), look at page 4/2. For a pre October 2000 TS, look at p4/1.

For pre Oct 2000 V6 p6/2 and Post Oct 2000 V6, page7.

Depending on the engine/year, the compressor coil may be fed from another relay ( 'main' relay or key operated supply relay ) or directly from the ignition switch.
 

·
Premium Member
Joined
·
1,165 Posts
You don't mention what year your car is from or if it a TS or V6. If you have the VIN you can check the production day of the car in ePER
But you don't see any 12V on pin 85 of the relay (Q22) right?
If this is correct I would propose to check connector G314 to see if the orange wire (to the relay) in the connector has a bad connection
 

·
Registered
Joined
·
434 Posts
Discussion Starter #8
Sorry, I should have said it's a TS and is CF2. PKR, thanks for the heads up on the manual pages. I have printed out section 55-26 but I only have a page 4, no 4/1 etc. I have the wiring diagram for chassis number post 6023907 and mine starts 606. According to that, the 12v supply goes to pin 85 on the relay and the feed from the ECU is pin 86.

The reason I had no supply to the coil on the relay is because I was checking the wrong pin! On mine the 12v feed goes to pin 86 and there is indeed a supply (Orange wire). Pin 85 is presumably the earth feed (white wire) and when the A/C is on there is no continuity between that pin and earth so it looks like I have no feed from ECU.

My thought goes back to low pressure and therefore no fluid. Is that a reasonable assumption? Is there anyway to test for fluid in the system or should I take it for a recharge and pressure test? Thanks.
 

·
Premium Member
Joined
·
1,165 Posts
You can measure the voltage level on the green-white wire and the black-purple wire on the presure sensor.
If the presure is too low or too high the pressure switch will be open and you should measure a different voltage on the two wires.
If the presure is ok you should measure the same voltage on the two wires (as the switch is closed)

Have you checked if the outdoor temperature measurement is ok?
If the climate control thinks the outdoor temperature is below approx. 3°C the compressor will not be engaged.
 

·
Registered
Joined
·
434 Posts
Discussion Starter #10
You can measure the voltage level on the green-white wire and the black-purple wire on the presure sensor.
If the presure is too low or too high the pressure switch will be open and you should measure a different voltage on the two wires.
If the presure is ok you should measure the same voltage on the two wires (as the switch is closed)

Have you checked if the outdoor temperature measurement is ok?
If the climate control thinks the outdoor temperature is below approx. 3°C the compressor will not be engaged.
Is the pressure switch attached to the dryer filter under the bumper? If it is, I tried to disconnect it and could not get a proper grip on it to pull it out due to the lack of space. Any tips to get it out? Also how do I check the outside temp is measuring ok? I checked on multi scan and it seemed consistent with the ambient temp. Is this the way to do it? Thanks.
 

·
Registered
Joined
·
4,627 Posts
Is the pressure switch attached to the dryer filter under the bumper? If it is, I tried to disconnect it and could not get a proper grip on it to pull it out due to the lack of space. Any tips to get it out? Also how do I check the outside temp is measuring ok? I checked on multi scan and it seemed consistent with the ambient temp. Is this the way to do it? Thanks.
You can also pick those wires up from a second connector between the radiator and air filter housing. It looks like this -

http://www.ebay.co.uk/itm/5Kit-Set-...582052?hash=item488b5a1564:g:agYAAOSwboVXOWKd

Much easier than disconnecting from the filter/drier!

The upper and lower air temperature sensors ( located within the heater unit ) will also be around ambient if the car hasn't been baking in the sun or recently used. So if all three sensors say the same thing, you can be confident they're all OK.
 

·
Registered
Joined
·
692 Posts
easiest way is to remove the bumper. remove the screws attaching it to the wheel arch trim and undo the 2 hex bolts underneath the headlights and the bumper simply slides out (you might need to unplug a couple of looms) Hex bolts might need penetrating oil and a bit of force as they are often rusty (use copper grease when refitting). Its a worthwhile exercise anyway as it makes removing the bumper a 10 minute job in the future in case you need to replace the radiator or condenser which is also much easier with the bumper off. Also, you can check the condition of the supporting irons which can snap due to rust which is why you see GTVs with sagging front bumpers
 

·
Registered
Joined
·
434 Posts
Discussion Starter #14
You can also pick those wires up from a second connector between the radiator and air filter housing. It looks like this -

http://www.ebay.co.uk/itm/5Kit-Set-...582052?hash=item488b5a1564:g:agYAAOSwboVXOWKd

Much easier than disconnecting from the filter/drier!

The upper and lower air temperature sensors ( located within the heater unit ) will also be around ambient if the car hasn't been baking in the sun or recently used. So if all three sensors say the same thing, you can be confident they're all OK.
Many thanks for pointing me in this direction. I'll check it out.
 

·
Registered
Joined
·
434 Posts
Discussion Starter #15
Many thanks for pointing me in this direction. I'll check it out.
I've found the connector and disconnected it, but which side am I checking? Is it the side which goes to the dryer? Thanks!
 

·
Registered
Joined
·
4,627 Posts
Look at the car side half of the connector and identify the pins with the Black/Purple and Green/White wires.

Measure the continuity between these pins on the pressure switch ( filter drier ) side of the connector.

If you have continuity, there is enough gas pressure in the system. No continuity, insufficient ( or maybe too much! ) pressure.

If you look at the same workshop manual document ( v3 pt 2 ), but under the first section for 1997 MY, go to section 55-26 page 28 and it goes into detail there about how the pressure switch works. A lot of this useful info was chopped out of the workshop manual for 1998 on.
 

·
Registered
Joined
·
434 Posts
Discussion Starter #17
Look at the car side half of the connector and identify the pins with the Black/Purple and Green/White wires.

Measure the continuity between these pins on the pressure switch ( filter drier ) side of the connector.

If you have continuity, there is enough gas pressure in the system. No continuity, insufficient ( or maybe too much! ) pressure.

If you look at the same workshop manual document ( v3 pt 2 ), but under the first section for 1997 MY, go to section 55-26 page 28 and it goes into detail there about how the pressure switch works. A lot of this useful info was chopped out of the workshop manual for 1998 on.
Many thanks for clarifying this. I'll check it out and report back....
 

·
Registered
Joined
·
434 Posts
Discussion Starter #18
Many thanks for clarifying this. I'll check it out and report back....
Look at the car side half of the connector and identify the pins with the Black/Purple and Green/White wires.

Measure the continuity between these pins on the pressure switch ( filter drier ) side of the connector.

If you have continuity, there is enough gas pressure in the system. No continuity, insufficient ( or maybe too much! ) pressure.

If you look at the same workshop manual document ( v3 pt 2 ), but under the first section for 1997 MY, go to section 55-26 page 28 and it goes into detail there about how the pressure switch works. A lot of this useful info was chopped out of the workshop manual for 1998 on.

There's no continuity, so I guess the next step is take it for a recharge and pressure test. Is there any way to tell if there is any fluid/gas in the system?
 

·
Registered
Joined
·
1,729 Posts
If you need any parts let me know. I have a almost complete aircon system from a phase 2. I know it was working cos it sprayed me with refrigerant when I undid the pipes.
 

·
Premium Member
Joined
·
1,165 Posts
There's no continuity, so I guess the next step is take it for a recharge and pressure test. Is there any way to tell if there is any fluid/gas in the system?
You can locate the Air-Con fillings points. They have a black dust cover. When you remove these you can see a valve. Just push carefully of this with a screwdriver to see if there is any gas in the system.

On my spider the fillings points is on the tubes on the right inner wing.
 
1 - 20 of 36 Posts
Top