My AC isn't turning on. The interior fan comes on when you push the AC button or the recirc button, however neither the compressor or auxiliary fan engage. This is a factory system by the way, not the dealer fit one.
Anybody got any ideas as to what might be going on. Is there anyway to jump the pressure switches to test if it just needs a regas?
Thanks
Matt
AC not engaging
Moderator: martauto
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Brianmoooore
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You are probably on the right track with your low gas theory, and you can jump the pressure switches as a test.
Black/yellow to black/red, I think.
Black/yellow to black/red, I think.
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Brianmoooore
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Rethink! You say the low speed electric fan doesn't run? This isn't controlled by the pressure switches in any way. It's switched on by power on the black/purple from the aircon switch, which, for this wire,is just a simple switch from the green/brown wire (12 volts ignition live from fuse 20).
Are you sure the low speed fan was working as it should before this current problem occurred?
Are you sure the low speed fan was working as it should before this current problem occurred?
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matt320
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Right, done some more investigation.
I'm not sure of the answer to that Brian, as my dear sister has had the car for four months and seems to have a magic touch for breaking anything within a ten foot ring of her.
I jumped the pins on the pressure switches with no result and started working back.
I also jumped the pins on the temp switch on the radiator and got the fan to kick in on high speed but not low speed.
Did have 12V on the power to the temp switch.
I ended up cracking open the fuse box and have discovered that the pc board in the fuse box is looking like the culprit. What I found was a burnt out stretch on the run from pin 86 on the low speed relay. Brian, where would this lead to and is it feasible to repair with a wore run bypassing the burnt out section. I can try and photograph it but will have to break out all the close up gear to get a shot of it and it is now 2310 here. If it helps the burnt out stretch runs on the board along the fuses 16 to approx 23. Would it be easier to replace the pcb, how hard is this?
Thanks for the help so far and would like to get this sorted before going back to work for the rest of the summer.
Matt
I'm not sure of the answer to that Brian, as my dear sister has had the car for four months and seems to have a magic touch for breaking anything within a ten foot ring of her.
I jumped the pins on the pressure switches with no result and started working back.
I also jumped the pins on the temp switch on the radiator and got the fan to kick in on high speed but not low speed.
Did have 12V on the power to the temp switch.I ended up cracking open the fuse box and have discovered that the pc board in the fuse box is looking like the culprit. What I found was a burnt out stretch on the run from pin 86 on the low speed relay. Brian, where would this lead to and is it feasible to repair with a wore run bypassing the burnt out section. I can try and photograph it but will have to break out all the close up gear to get a shot of it and it is now 2310 here. If it helps the burnt out stretch runs on the board along the fuses 16 to approx 23. Would it be easier to replace the pcb, how hard is this?
Thanks for the help so far and would like to get this sorted before going back to work for the rest of the summer.
Matt
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Brianmoooore
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It's perfectly in order to replace damaged tracks on a PCB with lengths of solid wire soldered in place, either insulated if necessary, or bare wire. Make sure any burnt board is removed, as this is carbon, and conducts electricity.
I'm still not convinced that there aren't two seperate faults, but repair this first, and go from there.
I'm still not convinced that there aren't two seperate faults, but repair this first, and go from there.
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matt320
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Hi Brian,
I have rerun the burnt out track with wire but still not getting low speed auxiliary fan either from the AC switch on the dash or from jumping the temp sender in the radiator, and the ac still isn't turning on (no compressor kicking in). Any ideas on how to try and trace the fault from here?
Matt
I have rerun the burnt out track with wire but still not getting low speed auxiliary fan either from the AC switch on the dash or from jumping the temp sender in the radiator, and the ac still isn't turning on (no compressor kicking in). Any ideas on how to try and trace the fault from here?
Matt
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Brianmoooore
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First point: Only use a 12 volt 5W or 21W bulb to check voltages - a meter will give misleading results.
Check for 12 volts power at the green/brown wire on pin 1 or 7 of the aircon switch, with the ignition on.
If present, check for power on the black/purple wire on pin 2, with the aircon and ignition on.
Check for 12 volts power at the green/brown wire on pin 1 or 7 of the aircon switch, with the ignition on.
If present, check for power on the black/purple wire on pin 2, with the aircon and ignition on.
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DanThe
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Pin 86 of the relays is earth, Pin 85 is the live 'wired' connection from the temp switch in the rad, relay is engaged then current travels through either fuse 3 or 18 to the fan, bridge the temp switch then check for power at the fuses, could be a faulty fan resistor
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matt320
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Dan,
Also did as you suggested and found no power at fuses 3 or 18 with the low speed fan jump at the radiator switch. So would this solve the no fan state (blown low speed resistor), or could it also be caused by the AC not turning on?
Matt
Also did as you suggested and found no power at fuses 3 or 18 with the low speed fan jump at the radiator switch. So would this solve the no fan state (blown low speed resistor), or could it also be caused by the AC not turning on?
Matt
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Brianmoooore
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Fuse 18 is connected directly to the fan motor, so no power here is as expected with the fan not running.
Fuse 3 is before the fan resistor, so no power here suggests relay K1 isn't on.
Pull out relay K1, and link together pins 30 and 87 of its base. Does this make the low speed fan run?
The next question is: Why doesn't K1 pull in when the temp. switch is jumped? Why doesn't it pull in when the aircon switch is on, since the 12 volts you've found on pin 2 of the switch should connect directly to K1's coil?
Is there 12 volts on the green/black wire at the temp switch, with the ignition on?
Pull out K1 and push the wires from your test bulb into 85 and 86 of it's base (ignition and aircon on). The bulb should light. If it doesn't, try one wire of the bulb earthed, and push the other wire into 85 and 86 in turn.
The wiring diagram says it should light with the bulb wire in 86, but there is an error or two on the wiring diagrams - some relays are shown with 85 and 86 the wrong way around.
Air con: I still think this is a seperate fault, and you've only discovered the fan problems because you've investigated the aircon problem.
Let's bypass all the auto control system, and check that the compressor works - connect the black/purple - the one that's at pin 2 of the aircon switch, relay K1, the plug by the engine ECU, and at the evaporator temp. regulator to the black/red at the low pressure switch, or the black/grey at the compressor clutch.
Fuse 3 is before the fan resistor, so no power here suggests relay K1 isn't on.
Pull out relay K1, and link together pins 30 and 87 of its base. Does this make the low speed fan run?
The next question is: Why doesn't K1 pull in when the temp. switch is jumped? Why doesn't it pull in when the aircon switch is on, since the 12 volts you've found on pin 2 of the switch should connect directly to K1's coil?
Is there 12 volts on the green/black wire at the temp switch, with the ignition on?
Pull out K1 and push the wires from your test bulb into 85 and 86 of it's base (ignition and aircon on). The bulb should light. If it doesn't, try one wire of the bulb earthed, and push the other wire into 85 and 86 in turn.
The wiring diagram says it should light with the bulb wire in 86, but there is an error or two on the wiring diagrams - some relays are shown with 85 and 86 the wrong way around.
Air con: I still think this is a seperate fault, and you've only discovered the fan problems because you've investigated the aircon problem.
Let's bypass all the auto control system, and check that the compressor works - connect the black/purple - the one that's at pin 2 of the aircon switch, relay K1, the plug by the engine ECU, and at the evaporator temp. regulator to the black/red at the low pressure switch, or the black/grey at the compressor clutch.
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matt320
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Hi Brian
I linked pins 30 and 87 of relay K1 and the low speed fan kicked in. It didn't come to life immediately but did once I moved the relay in the socket. I am guessing it wasn't making good contact due to the linking wire on the relay. It stayed working consistently after this however while the jumped relay was in.
I confirmed there is 12V on the green/black wire at the temp switch with the ignition on, bulb lit up well.
The test light refused to light when testing both pins 85 and 86 in all situations you stated above, so no power present there. I was using the bolts on top of the front strut turret as an earth, I figured these would be OK as the other side of the car has a bolt used for this.
Aircon, when bypassing all auto controls and taking a feed from pin 2 of the AC switch to the black red of the low pressure switch, the compressor kicked in and ran beautifully, blowing very cold air. While it was running I checked the inspection window on the dryer and there were minimal bubbles present so I am guessing the system is charged ok.
Where should I head next with this?
Thanks
Matt
I linked pins 30 and 87 of relay K1 and the low speed fan kicked in. It didn't come to life immediately but did once I moved the relay in the socket. I am guessing it wasn't making good contact due to the linking wire on the relay. It stayed working consistently after this however while the jumped relay was in.
I confirmed there is 12V on the green/black wire at the temp switch with the ignition on, bulb lit up well.
The test light refused to light when testing both pins 85 and 86 in all situations you stated above, so no power present there. I was using the bolts on top of the front strut turret as an earth, I figured these would be OK as the other side of the car has a bolt used for this.
Aircon, when bypassing all auto controls and taking a feed from pin 2 of the AC switch to the black red of the low pressure switch, the compressor kicked in and ran beautifully, blowing very cold air. While it was running I checked the inspection window on the dryer and there were minimal bubbles present so I am guessing the system is charged ok.
Where should I head next with this?
Thanks
Matt
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Brianmoooore
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Any poor connections at 30 and 87 of K1 need to be sorted, or there will soon be more burning to contend with!Brianmoooore wrote: Is there 12 volts on the green/black wire at the temp switch, with the ignition on?
The problem with the actual aircon is now narrowed down to the pressure switches and evaporator temp. regulator and its temp. sensor.
If linking out the black/yellow and black/red at the low pressure switch doesn't make the compressor run, then that only leaves the evap temp controller and sensor, and I'm afraid I've no experience of problems with these.
Do you have a circuit diagram of this area?
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Brianmoooore
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Evap controller is held in place by a spring clip just above/behind the electric water valve on the LH side of the heater box. Easy to get at by removing the panels above and to the right of the glovebox, if your steering wheel is on the side it should be.
Note that the Russian wiring diagrams have the pin numbers all wrong.
1 and 3 are brown
2 is yellow/black
4 is purple/black
5 is purple
6 is white black.
The path the compressor clutch takes through the module is a normally open relay between pins 4 and 5. I.e. power goes in on 4 (purple/black) and out on 5 (purple) which then becomes black/white at the high pressure switch.
Note that the Russian wiring diagrams have the pin numbers all wrong.
1 and 3 are brown
2 is yellow/black
4 is purple/black
5 is purple
6 is white black.
The path the compressor clutch takes through the module is a normally open relay between pins 4 and 5. I.e. power goes in on 4 (purple/black) and out on 5 (purple) which then becomes black/white at the high pressure switch.
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matt320
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Hi Brian,
I think I have both issues sussed. The evap temp switch was the culprit (mines a chrome bumper). This was showing an open circuit in 22 degree ambient, so bridged the two wires (violet and black/white) and system pulled in. My understanding is this switch should be open to prevent the evap from freezing up but closed when system is ok to run. Will have to get a new evap temp switch for an early set up AC system.
The low speed aux fan turned out to be a bad earth at the relay (K1). Have re done the earth to the relay and this is now working as it should. Thanks for all your help on this, it has been invaluable.
Next, does anyone know where to get an early evap temp switch, the dealers here asked if I was sitting down before he gave me the price.
Matt
I think I have both issues sussed. The evap temp switch was the culprit (mines a chrome bumper). This was showing an open circuit in 22 degree ambient, so bridged the two wires (violet and black/white) and system pulled in. My understanding is this switch should be open to prevent the evap from freezing up but closed when system is ok to run. Will have to get a new evap temp switch for an early set up AC system.
The low speed aux fan turned out to be a bad earth at the relay (K1). Have re done the earth to the relay and this is now working as it should. Thanks for all your help on this, it has been invaluable.
Next, does anyone know where to get an early evap temp switch, the dealers here asked if I was sitting down before he gave me the price.
Matt