Air-con compressor not coming on after re-gas

[technics100]

I just changed my air-con rad tonight and got the system re-gassed.  It's holding pressure fine but the A/C still won't work as there is no life out of the compressor.  Is there anyway to test it and or it's clutch to see what's4 wrong?

 

Thanks

[SmithyVrs]

Have you checked for a power feed at the connector plug mate?

[rossm]

Assuming power to the compressor is okay, are you certain the system has been refilled with the correct amount (weight) of gas?  If too much is put in, the compressor can have difficulties starting up.  A garage with the right air con kit will be able to tell you the weight of gas currently in the system, what it should be and refill with the correct amount.

 

I believe the Octavia II needs 550g of gas, not sure about the Mk1 though.

[benh78]

Check your radiator fans when on aircon both should come on low speed if they don't that's your problem very common fault you can either do the resistor mod or fit new fans you may also want to change the fan control module under the battery v cheap in eBay. Search mkiv forum there is an excellent write up on how to test both fan speeds to see where the fault lies. Was what stopped my aircon workings on 2 Octavias and golf mkiv

[rover220]

Check your radiator fans when on aircon both should come on low speed if they don't that's your problem very common fault you can either do the resistor mod or fit new fans you may also want to change the fan control module under the battery v cheap in eBay. Search mkiv forum there is an excellent write up on how to test both fan speeds to see where the fault lies. Was what stopped my aircon workings on 2 Octavias and golf mkiv

The aircon should still work even if the fans dont

[benh78]

On both of mine aircon didn't work until fans and fan controller module worked.

[vee8essie]

check the clutch common on the vag cars for this to fail over time you will get some cold air but not a great deal that is a clue that  the clutch has gone then you need a new pump you will also need the numbers of the back/end of the pump to get the correct part

[yesiamtom]

^If the clutch has gone...just replace the clutch?! I did and my aircon fired straight back to life. I think it had sat dormant for at least a year, but in reality probably a lot longer. 

 

It's a lot cheaper and easier.

[technics100]

Thanks guys, I will give it a scan with vag-com tonight and then do a visual check.  Does anyone know what grams are required for the AC system?

 

Is there a check for the clutch?  I will also check the fans as I don't believe they were on last night.

 

Also, what a bloody pain to change the AC rad, whole front end taken off the car!! It started off with just removing the 4 bolts for the slam panel, but nothing would budge, ended up like that!! hmm

 

[technics100]

Just ran vag-com there now.  so it had a couple of codes, but they cleared and wouldn't come back. I assume from the whole that was in the AC rad.  flicking through the measuring blocks and in group 001, compressor shut-off switches between 0.0 6.0 when econ and auto are selected suggesting the compressor is coming on? or thinks it is anyway.  The clutch is still present, but is there a way to test it? can the clutch just be replaced by itself? 

[smileonimpact]

Could possibly be a fault with either the high or low pressure switches, and more than likely the low pressure switch, this will prevent the compressor clutch from coming on if it has failed.

[rover220]

If the compressor does not fire up neither will the fans so don't worry about them till you know they should be on.

[technics100]

It did have a F129 pressure switch code, but I cleared that and it wouldn't come back. I assume that would be from the low pressure due to the whole in teh AC rad.  Also one fan was running behind the rad..

[benh78]

Hi when it's set for air con both fans should be running at low speed do you have the climtronic control?

When I was researching mine people had wired 12v direct onto the aircon clutch to prove that was working.

As for the fans each has 2 circuits high and low speed hence the 3 wires to each fan you can test both fans and both speed settings with a bit of wire I'll try and find a link to the guide. I just changed the fan control module on all my cars anyway it's under the battery as they are cheap 2nd hand on ebay

[meaty101]

http://m.youtube.com/watch?v=Af-jT9cAioM

Try this.

[technics100]

Cheers, I will give it a go.  Yes. It has climatronic..

[technics100]

Just tried that, so I have the LHS fan working on low speed and high speed, nothing from the RHS fan.  New fan controller then and or RHS fan? 

[benh78]

What I did for both fans is disconnect the plug there are 3 pins and somewhere on the mkiv forum there is a how to connect the negative to one pin and then positive to another and you can prove whether both speeds are working. Most likely you will need a new fan or the resistor mod. I found I could replace the fans just by undoing the 3 bolts that hold it into the radiator and lift them out took 10 mins per fan going slow. If air con still doesn't work but you've got the fans working I.e both running at slow speed then swap the fan control module anyway. If not working could be compressor clutch or pressure switch in air con system - good luck

[benh78]

Found this on a quick

The fan test in Andymacs first post in this thread is sufficient to

identify the low speed problem, I have had several requests for further

fault finding

details to establish if any other fan related faults are present.

First the fans themselves.

Disconnect the fan connector and measure, with a multimeter, the

resistance between the red/white wire and the brown wire, it should be

a value less than 10ohms, a much higher value indicates a burnt out

internal resistor. Next measure the resistance between the red/black

wire and the brown wire it should also be a value less than 10 ohms, a

much higher value indicates a burnt out fan.

Next the fan controller, fuses etc.

The test detailed is taken from the VW repair manual for the V5.

Caution keep hands etc away from the fans during this test as they are expected to run:

Reconnect both fan connectors, if still disconnected, and disconnect the 3 pin connector from the radiator fan thermo switch.

Bridge contact 1 and contact 2 with a short piece of wire, the fans should run at low speed.

Switch on ignition, bridge contact 2 and contact 3 with a short piece of wire, the fans should run at high speed.

Switch off ignition, reconnect thermo switch connector.

To identify the connector pin numbers, hold the connector facing you

with connector latching mechanism at 2 o'clock, pin1 is then at

12 o'clock, pin 2 at 4 o'clock and pin 3 at 8 o'clock.

[Rob1971]

You may find that if your engine coolant temp sensor is faulty, the air con won't work. It is a safety system to prevent the engine overheating as the condensor is hot when the compressed gas enters. Because it is next to the coolant radiator, the heat may transfer to the radiator etc. Your temperature gauge may still read correct as mine did. Maybe it's worth checking that before you spend lots of money! Good luck.

[deepu]

Check your radiator fans when on aircon both should come on low speed if they don't that's your problem very common fault you can either do the resistor mod or fit new fans you may also want to change the fan control module under the battery v cheap in eBay. Search mkiv forum there is an excellent write up on how to test both fan speeds to see where the fault lies. Was what stopped my aircon workings on 2 Octavias and golf mkiv

Hi.

 

Can you guide me to the mkiv forum. I am unable to find it on my own.

 

Thanks in advance.

[whitep]

doesnt air con stop working at 3 degrees?

[Railroad]

The A/C won't switch on if the outside air temperature is below 6 degrees Celsius. This is a safety feature to prevent ice forming on the evaporator which could damage it. So unless you're operating your air conditioning inside a warm workshop I wouldn't be expecting it to work. Wait until the weather warms up and try again.

[Silver Bullet]

Assuming power to the compressor is okay, are you certain the system has been refilled with the correct amount (weight) of gas?  If too much is put in, the compressor can have difficulties starting up.  A garage with the right air con kit will be able to tell you the weight of gas currently in the system, what it should be and refill with the correct amount.

 

I believe the Octavia II needs 550g of gas, not sure about the Mk1 though.

 

For future reference (Mk1 octy vrs) :-