Help! My Aircon burst!

[tixy]

Hi all,

Golf 1.6SE 2001, AC with knobs

we've had some great weather recently, but my AC packed in on one of the really hot days

I was driving back from london and realised the AC wasnt working and an oil sensor warning was sounding. the AC light goes on but it didnt cool, also the recirc light doesnt go on when the buttons pressed

I parked up only to hear a terrible hissing sound, it was my pressure switch spraying out all my aircon gas - pretty spectacular as it was steaming against the hot engine!

I replaced the pressure switch for £50, got it refilled in Kwikfit and it didnt leak but it also didnt sort out the problem, aircon was blowing warm

i've connected up vagcom with a wire from fleabay a mate had:

VAG-COM Version: Release 409.1-S

00562 - Sensor for Oil Level/Temperature (G266)
30-00 - Open or Short to B+
16955 - Cruise/Brake Switch (A) Circ Malfunction
P0571
16916 - A/C Refrigerant Pressure Sensor (G65) Circuit Low Input
P0532 - 000 - -
17978 - Engine Start Blocked by Immobilizer
P1570 - 000 - - - Intermittent
01314 - Engine Control Module
49-10 - No Communications - Intermittent

i've reset all except 00562 (the oil level light still comes up), the EPC lights gone now.
i couldnt communicate with the Auto HVAC module, for some reason it just couldnt find it "No response from controller!" (I dont have climate control, does that make a difference?)

The AC light comes on but it still blows warm, the recirc button is still disabled.

Any ideas how to get the AC going? Why cant i communicate with the Auto HVAC controller to reset the aircon? whats with the recirc button? Do you think this was more than a replace-the-pressure-switch job?

thanks

[herby0001]

I would have thought Auto HVAC (I guess it's Heating Ventilation and Air Con?) was on cars that had climate control. I may be wrong, but IIRC I've never been able to connect to Auto HVAC on mine and I just have the AC button.

Not needed to troubleshoot AC problems yet, but I would first check whether you hear a clunk whenever you switch the AC on. This would be the clutch engaging to drive the compressor.

The recirculation button doesn't work if the airflow is directed at the windscreen. Change it to your feet or dash vents and try it then.

[tixy]

thanks for the reply, really appreciate it

i wont bother to keep trying to connect to the auto hvac controller then

yes the ac button lights up and the engine does rev a little higher, but i dont hear a clunk really and i don't believe i ever have when it was working!

i know about the recirc button and have tried to face it to feet/forward, still doesnt light up.....weird

in the meantime the EPC light has come up again, despite clearing it. i can keep clearing it i suppose and im not sure if its related to the aircon not working or the oil level warning.

time to troubleshoot the aircon now?

cheers

[tixy]

actually you're right i dont hear a clunk, it does rev a little higher but certainly not as much as it used to
any help?

"The compressors used in vehicle air conditioners
are oil-lubricated displacement compressors.
They operate only when the air conditioner is
switched on, and this is controlled by means of a
magnetic clutch."

how do i check whether this magnetic clutch is working?

"if the low pressure sensor trips it stops the compressor from activating (to protect it)",
"if the system leaks the switch will shut it off so the pump wont run dry and seize up." is this true and if so how do you reverse it?

theres also talk of 'jumping the pins' and restarting the compressor. Any ideas on how to do this? if it needs 12V do i just connect some jump leads up directly from the battery to the compressor connector?!

I ran vagcom again today and it came up with the following fault:

16916 - A/C Refrigerant Pressure Sensor (G65) Circuit Low Input

i had changed the pressure sensor and regassed the aircon.

[herby0001]

Sorry, I don't know the answers to your questions on testing the clutch and shorting pins, except that it sounds like you still have a leak in your a/c system. Unless you get any answers here and being in your position, I would take it to a VW specialist/independent and not take it to places like kwik-fit, who will just do simple tasks like re-gassing. They do not have the know-how to troubleshoot the problem further.

[tixy]

ok summer time again
and i never did get round to fixing this
and ive forgotten all the tonnes of research i had to do!

any help?
basically i need instruction on how to jump start the aircon compressor

i assume i need the engine on with ac button on?
i'm gonna try jumping with jumpstart leads and see if i can find any terminals on the compressor, connect it and see what happens

unless someone screams NO! of course

[SammoVWT]

Compressors can run on low pressure no problem, if theres no oil in the compressor parts, however it will seize!

If its short on gas it will just not produce much cooling.

The sensor might also show a fault when starting/off as the pressure generated will be low, but it really depends on the system. If that fault came up with the AC running, then its short on gas (pressure sensor related).

Dont over gas the AC or you could risk the compressor crushing itself and blowing up due to too much liquid. You cant compress liquid well (Virtually nothing).

If you can get the compressor running I dont see it as a problem, I doubt it will be running off more than 12V, just be aware it might suck up some juice from the battery starting if its seized (or from a booster pack), unless its driven off the cam etc, then it wont apply to jump start it.

[tixy]

thanks for the quick reply
i checked it again to remind myself what the problem was

when you switch the AC button on it lights up (albeit dimly) and the engine revs slightly higher but the compressor clutch doesnt spin, i.e. the magnet doesnt engage

i need this magnet engaging (apparently its a failsafe that it cuts out when theres no pressure in the system)

anyway i had another look and theres a wire going into the compressor but no obvious way i can see to jump it with leads

is there any place above the battery i can fiddle with to jump it? i remember seeing connectors and fuses there but dont have a map of what they do

any help would be much appreciated

[SammoVWT]

My guess the pressure cut out could be because of potential oil loss, you wouldnt want the AC engaged when the clutch kicks in with no oil and then a sudden siezing of the compressor.

You could probably bypass it for a test, or even get the magnetic clutch to fire seperately, but it depends on the parts.

Did you get the pressure sensor checked out?

My guess is the engine is revving higher to compensate for when the AC is running, but someone who made that ECU forgot to allow for when the system is tripped out to not increase engine revs.

<snip> just read you replaced it, you should look for the relay that engages the AC clutch, it could have failed, or some wiring has broken between the pressure sensor/ecu, or the clutch itself may have failed and be driving down to earth, most likely relay/ cable breakage from thinking about it though

Do you know the sensor part #? Pressure sensors tend to be active sensors and therefore need power in to get a signal out, might be a replaced sensor, but no power going to it resulting in a low value - just a thought

[kenney]

You need to get someone to measure the pressure in the system,this way you can tell if there is enough gass