A/C Issues

[jbadazz]

Hey guys,


I have a VW Golf MK4 2lt 01 model (auto). I have a problem there is no cold air been blowing out. I have had checked the pressure rate on both piping and for gas leaks. We checked power to the compressor unit and was zero. We bypassed the unit and applied power to the compressor and all works well.

We have checked all fuses on the driver side panel (even though picture diagrams don't really help) and all fuses turned out fine. Checked the fuses where the battery is and there is power there also.

I was after any information or a Mk4 Golf service and repair manual or the ac wiring diagram it would be of great help. I am aware there are fuses, resistors and a sort of ciruit breaker which the air con systems all ties together, but don't want to touch that unless i have the schematics for it.

Cheers,

John

[Jmac]

Hi mate, check the fusebox on top of your battery, im sure the fuseholder will be melted due to a dodgy fan. Replace the fusebox and you should be sweet for a while, and have the fans checked out anyway. Normally a shorting fan overloads the fusebox. Get your sparky to check the current draw on the fans, changed heaps of fans on these. This weather will show up all the elec gremlins for sure, having heaps of elec fun at the moment
Sounds like the rest of the system is in check.
Jmac

[Umai Naa!!]

Also check the pressure switch.

A faulty one had me scratching my head for a bit.

[Jmac]

Bridge it then you will know
Cheers
Jmac

[Umai Naa!!]

Eggzackery

[jbadazz]

JMAC. I have checked the fuse box on top of battery and looks brand new. There is power there and the fuses all have contnuity. When i took out the furthest fuse it turned of the fans. My fans do work. Although the Air con compressor itself has a connector with two cables going into it. Green + .. Brown is common... ThAt is where i don't have power which in turn doesn't power up my compressor hence no air con.

I am looking for the feed of that compressor. All fuses are 100% both in cabin and the ones at the battery terminal. I know there are fuses, breakers and resistors at the computer behind the glove box. I have a hunch it could be that.

Umai Naa... Pressure switch?? Please explain. As far i have been told all pressure in the lines are 100%. And i have no leaks.

JMAC.. Bridge? Sorry i don't understand. Please elaborate.

BTW anyone have the service repair manual for MK4 Golf?

Thanks guys for your help...

[Umai Naa!!]

There's a pressure switch on the high pressure line at the top of the firewall above the engine in the engine bay. If that's on the fritz, there will be no power at the compressor. The pressure switch basicaclly sees how much pressure is in the system. Too high or too low, no A/C. If it's failed altogether, no power to the compressor.

What Jmac is talking about, in regards to bridging, is to electrically bypass the pressure switch. This is easier said than done in this case, as there's more than two wires. Without the wiring diagram, and a basic understanding of the circuit, you'll probably pop a few fuses.

[Jmac]

I gather you have plenty gas??? bridging the switch will make the compressor work ok , but the pressure switch might be doing its job. low pressure then the compressor wont kick in, power it up is fine, but the system might be telling it to stay off. Dont get me wrong it may still be the pressure switch, understand we are diagnosing over the internet, easier with a set of gauges on ( which NEVER lie) and watch what its doing.
Cheers
Jmac
If you need further wiring help pm mate

[jbadazz]

Umai Naa... Thanks for that information. But as you said without the schematics im pretty hesitant to do it. ( If it was a jap car no worries, but euro cars too scared)

Jmac.. I understand stand that too. It might be cutting off for that reason. My mechanic is actually my uncle. We had the gauges pluged in and he told me they where low on both gauges. But from further troubleshooting as we applied power to the compressor externally the gauges moved to what he said was acceptable. He mentioned how much pressure was needed although i didn't remember those values. He told me what was wrong but he isn't keen to play with it unless he has the schematics.

i will pm you jmac for wiring help.. cheers..

Appreciate the help.