A/C Problem

[The Fixer]

A/C was not working had it serviced and re-gassed, worked for a while then stop but started to work again, now it is not working (clutch not engaging).
Removed the engine fan, stripped it down and Ohms tested the wiring all appears OK, then check the relay, it activated when tested next checked the voltage on the relay with the ignition on, voltage to both large pins, turn ignition off voltage to only one large pin. Anyone have any idea what may be causing the problem??

 

[ozVTR]

Sounds like you have a refrigerant leak. System works off pressure in the high side. If the pressure gets below a certain point the system wont work. The clutch will respond to test inputs though but not while the engine is running. The stop-then-start of the system might be because that day was warm and bumped the pressure up just enough for it to work but I bet it's performance was poor. You can inspect the system for oil leaks, tell-tale of gas leaks. However a lot of slow leaks don't leak out oil and are hard to find.
Yes, on some systems cooling fan faults will also shut down the aircon, however if your car has relays to run the thermo fans, that's not typically the fault. It's the variable speed fan controllers that give the problems.
You need to check the pressure in the system. At rest on an "average" temperature day (mild), the pressure should be about 100PSI(g). Unfortunately you will need a set of service gauges to do that.
Even though the engine ECU monitors the high side pressure, I have not seen a display of it in PP or LEXIA. But if anyone knows how to get it out of PP or LEXIA I would be delighted.

 

[jo proffi]

I have just had exactly the same issue on my soon to be driven over a cliff i30, except I didn't do any of the electrical test you did.
Paid for the mechanic to sniff out the leak with his wizz bang leak sniffer, and of course after much scrutiny and yoga (and more expense), leak was found to be under the dash, in the hardest place to find, and the hardest place to service. GRR

$2000+ quote to replace,

Bough a new car with AC that works

 

[schlitzaugen]

Hang on a second. If the clutch pulley is not engaging how would you expect it to work? Or am I missing something?

I would suggest you disconnect all the relevant circuitry and power the clutch directly from a healthy 12V first. That should clarify something. Next move to relays and such.

 

[The Fixer]

As the saying goes If it ain't broke don't fix it, well the clutch was engaging and the system worked ok but I had not re-taped (insulated) all of the wires, took it to pieces and did so, put it all back together, front grill etc lo and behold the clutch didn't engage. So I thought I would ask you good persons if they might know what to do.

 

[ozVTR]

So you removed the cooling fan for some reason and disturbed the wiring? You then put it all back and everything worked? Once more you pulled the fan and ETC out to tape up the wiring, put it all back and now the aircon doesn't work?
IS the cooling fan working? Does the cooling fan cycle (on/off) when the engine gets up to temp at idle?
The engine ECU controls both the compressor clutch and he radiator cooling fan. If the engine ECU believes the cooing fan is not working it will not engage the compressor.
I do not have a circuit diagram for the 407 so I don't know how the fan is driven or how the engine ECU monitors the fan circuit.
However if the cooling fan does not cycle at idle that probably explains why the aircon is not working.
If the cooling fan is working and cycling at idle then there is a problem with the fan monitoring system or you are back to investigating a leak or whatever in the aircon system.

 

[Armidillo]

Air con stops working in my 406 from time to time. Cause has pretty much always been wear in the ignition switch. I replace with cheap Chinese knock-off and it works again, but only for a couple of years. Last time I bought 2 so I've got spare on hand when the inevitable happens...

When this happens I can still test compressor with PP2000 - passes every time! Also am pretty certain there are no (relevant) fault codes when this happens.

 

[dmccurtayne]

Air con stops working in my 406 from time to time. Cause has pretty much always been wear in the ignition switch. I replace with cheap Chinese knock-off and it works again, but only for a couple of years. Last time I bought 2 so I've got spare on hand when the inevitable happens...

When this happens I can still test compressor with PP2000 - passes every time! Also am pretty certain there are no (relevant) fault codes when this happens.

I used to put relays into that side of the ignition switch that runs the fan.

 

[The Fixer]

Hang on a second. If the clutch pulley is not engaging how would you expect it to work? Or am I missing something?

I would suggest you disconnect all the relevant circuitry and power the clutch directly from a healthy 12V first. That should clarify something. Next move to relays and such.

thanks for you reply,\.
When you say "power the clutch directly from a healthy !@v first", which connection do I apply the 12v to?

 

[IRAs-Frog]

Have you checked for error codes using an OBD reader?
My T7 308 A/C stopped working and only by chance did I connect my OBD reader up and it reported an error with the thermostat!
It appears that the A/C relies on a switch in the thermostat. Sorry, I can't remember the code.
My A/C came good after I purchase a new thermostat and before I could fit the new thermostat.

 

[The Fixer]

About 3 weeks ago I had the A/C re gassed. When the A/C stopped working I took the car back to have them check the A/C, they told /showed me, what they say was a leak of the gas, in the front top near the pully, which they highlighted wit UV light, (stain showed yellow) then told me the total cost would $3,450.00, since that is about the value of the car, I declined their offer. Somehow I still think it is something to do with the wiring, as I said in my post, it was working great until I disconnected the wiring the wrap in insulating tape, which I haven't got around to yet, I will post the results as soon as I find the time to do the job.
Thanks for you suggestion, it may well be the wiring from the Temperature Sensor!!

 

[The Fixer]

Hang on a second. If the clutch pulley is not engaging how would you expect it to work? Or am I missing something?

I would suggest you disconnect all the relevant circuitry and power the clutch directly from a healthy 12V first. That should clarify something. Next move to relays and such.

Hi, which wiring conection do I apply the 12v to???
Cheers

 

[borosa]

You ignore the advice of ozVTR and your mechanic who both said what the issue is - your mechanic going as far as to actually prove it to you. No gas, no aircon. The clutch will NOT engage if the gas pressure is low. It has nothing to do with the electrics, the system is working exactly as it is designed to. Manually engaging the clutch with the system in this state will ensure you do more damage, this time to the compressor, but hey, what do we know.

 

[Armidillo]

I know it would cost $100 or so, but can you get a mechanic (perhaps a different one) to test AC gas pressure. If it is Ok, then pursue your wiring theory. If it is not Ok, get him to add gas and see if system starts working. Yes it will leak out (if there really is a leak) and AC will soon stop working again, but then you will know for certain one way or the other...

 

[The Fixer]

I know it would cost $100 or so, but can you get a mechanic (perhaps a different one) to test AC gas pressure. If it is Ok, then pursue your wiring theory. If it is not Ok, get him to add gas and see if system starts working. Yes it will leak out (if there really is a leak) and AC will soon stop working again, but then you will know for certain one way or the other...

Thanks Armidillo, I have done just that, the system is fully charge with gas. It appears that the lubricant is what has leaked out (shines purple under UV light).
Ihave been able to activate the clutch, whith engine off. So now I will buy a new compressor, through Alibaba, they have the model I need for $160.00 +$130.00 freight.
Cheers

 

[Armidillo]

Wow - that's very cheap!! Bit surprised by the freight charge though.

Re. the leak - someone else will confirm, but I'm pretty sure that you can't lose compressor oil (the lubricant) without a significant loss of gas at the same time...

 

[The Fixer]

Wow - that's very cheap!! Bit surprised by the freight charge though.

Re. the leak - someone else will confirm, but I'm pretty sure that you can't lose compressor oil (the lubricant) without a significant loss of gas at the same time...

I went to an Auto A/C and while I watched he check the gas by opening (pushed the relief valve) and gas under pressure came out, he told me that, the lack of gas was not the problem, he did not mention the oil lubricant.
Re the unit in china checkout the attachment.

 

[ozVTR]

I went to an Auto A/C and while I watched he check the gas by opening (pushed the relief valve) and gas under pressure came out, he told me that, the lack of gas was not the problem, he did not mention the oil lubricant.
Re the unit in china checkout the attachment.

That's not very professional. He could have put the service gauges on the system to check the static pressure. Just because gas comes out does not prove there is enough pressure to engage the compressor. HOWEVER, we will take the tech at his word and assume there is sufficient charge to activate the system.
As Armadillo says, you can loose refrigerant without loosing oil but it's nearly impossible to loose oil without loosing refrigerant! So you can assume the oil quantity in the system is sufficient.
Given you claim that you got the compressor clutch to engage, then we can assume that the compressor is serviceable and it appears that the air conditioning is not working because the system is not engaging the clutch.
You have not answered my question as to whether the fans are working or not.
Seeing as you say you were "fiddling" with fan circuit when all of this happened, I would assume that is your problem.
While we have NOT eliminated every other possible cause of failure, I would assume there is a problem with the fan power or feedback to the engine ECU from the fan circuit.
Are the fans otherwise working correctly?

 

[pugwash]

is it posssibl that the wires to the pressure switch ,have been disconected inadvertantly while fiddling with the fan wireing ,thereby giveing the impresion that the system is low on gas when in fact it isnt .PUGS sorry about the spelling my mouse has died ,christmas morning and my big fingers arnt copeing with this touch sensitive thing

 

[ozVTR]

About 3 weeks ago I had the A/C re gassed. When the A/C stopped working I took the car back to have them check the A/C, they told /showed me, what they say was a leak of the gas, in the front top near the pully, which they highlighted wit UV light, (stain showed yellow) then told me the total cost would $3,450.00, since that is about the value of the car, I declined their offer. Somehow I still think it is something to do with the wiring, as I said in my post, it was working great until I disconnected the wiring the wrap in insulating tape, which I haven't got around to yet, I will post the results as soon as I find the time to do the job.
Thanks for you suggestion, it may well be the wiring from the Temperature Sensor!!

It's a pity that the tech did not actually check the pressure in the system.
You have two diametrically opposed conditions:
1) Oil/dye on the outside of the compressor indicating a leak.
2) No loss of pressure/refrigerant (apparently).
I can not establish, in fact, how dye got on the outside of the compressor and yet the system pressure is OK. Is it a slight leak but there is still enough refrigerant to run the system? Is the dye left over from a previous failure? Don't know.
As I said it is possible to have pressure in the system, but not enough to activate the clutch. This establishes a possible leak from the compressor.
You MUST establish that at least one part of the system is working correctly! Without some sort of proof that a thing is or isn't working it's all assumption, and you know what happens when you ass-u-me!
So far you have only proven (in my mind) that the clutch can be made to engage, but that is not of much help. A good start, but you need to keep going.
However, my assumption above still stands. In the absence of further evidence; it was working before you fiddled with it, then it stopped after...therefor disturbing it is the cause of the failure.