Does anyone know why my AC works intermittently? On the hottest day of the year it didn't turn on and I deemed it "empty". 

 

Today it has turned back on blowing very cold air but the fans were going up and down in speed constantly with cold air. 

 

Can anyone give me an idea where to start looking?

Sounds like its low on gas to me, outside temp will affect the pressure it runs at, so the pressure switch is potentially stopping it.

 

Take it to kwik fit, get it vac'd / emptied and charged properly so you have a starting point, then go from there......otherwise you have no clue where to start.

Or maybe even ATS, look for their £38.99 offer, I used them last month, make sure anyone that works on your AC refits the charging port dust cover - I didn't so had to buy a new one which cost a bit!

Its not cooling or the fan does not switch on?

It is cooling now but the fan goes up and down like every second and the display bars don't move but the fan speed changes. I'l book it in a garage to start with.

also is it worth mentioning that I have one of these gauges? Never had the bottle and never inteded using it for that purpose

 

I plugged it to the H line i think (only fits one or the other) and the pressure was all the way to the redline. I used it on other cars before to check the pressure in the AC system and when it recorded low it meant it needed recharging. I think...

 

Also, does a pressurised system means it is re-charged? Or can a system be pressurised with no gas in it?

 

I have booked it a t my local for £60. I have both kwik and ATS but I trust none due to bad experiences on both shops in the past. They were both in and out tyre/MOT jobs, came out with damaged/limp mode vehicle. Story for another day

Edited 19 August, 20205 yr by Bertie90

If its cooling, the problem could be with the fan control, blower speed resistor, fan EM..

Update - Dropped it at the garage today, 10 min later they called back saying the AC is blowing cold air (it was a 1 digit reading) and the system is charged. They can't see anything obvious been advised to bring it in when not working.

 

What are my next steps now?

11 hours ago, pavinjo said:

If its cooling, the problem could be with the fan control, blower speed resistor, fan EM..

I'm a novice when it comes to AC. Is that ECU controlled?

My guess is that your radiator cooling fans are not working properly and on a very hot day the condenser core was too hot and the ECU prevented the aircon from switching on.

Surprised your mechanic did not check them.

@Bertie90, that was the Low side you were connecting that pressure gauge into, as others have said, it sounds like the condenser fan or its control is not behaving.  You always fill from the Low side.

right ok, soo....? lol what do I do now?

Can you feel loss of power or RPM fluctuation when the compressor kicks in? If the inner fan is working intermitently I guess its something within the cabin.

 

 

2 minutes ago, pavinjo said:

Can you feel loss of power or RPM fluctuation when the compressor kicks in? If the inner fan is working intermitently I guess its something within the cabin.

 

 

yes, when I press the AC button I can hear the tone of the engine change slightly but only at idle. I don't feel loss of power as such when driving.  I think I will monitor it for now, and I'll see what Haynes says in the manual, if anything.

Ok, but don't disregard what above gents are saying, they are far more experienced than me, this is only my reasoning

 

 

Seems climatronic has few sensors more than the old manual mk1 AC. Also the blower speed is controlled by  control unit, not the old resistor type control. You should read fault codes first by vcds and go from there

I need to find someione with VCDS. I knew I should have bought one a while ago

Edited 21 August, 20205 yr by Bertie90

1 hour ago, Bertie90 said:

I need to find someione with VCDS. I knew I should have bought one a while ago

 

You need to check your radiator cooling fans are running flat out as soon as you switch the aircon on, you can do that by simply opening the bonnet and using your eyes and ears.

One thing that I'm not sure that you have confirmed, with the AC switched off, does the cabin fan run at a steady speed if you demand lowish temperatures?

 

What I'm trying to get you to do is to make sure, to start with, if this is a cabin fan or its control issue, after proving that the cabin fan works okay, then move onto what has been suggested above.

 

No magic, just needs you to work through all the basic stuff first before moving onto the chiller side of things.

On 18/08/2020 at 22:23, Bertie90 said:

...On the hottest day of the year it didn't turn on...

 

I think this is the most important clue, it started working when the weather got cooler.

3 hours ago, sepulchrave said:

 

You need to check your radiator cooling fans are running flat out as soon as you switch the aircon on, you can do that by simply opening the bonnet and using your eyes and ears.

 

They don't turn on at all when I switch the AC on. I have never noticed that with the AC on I must admit, as a matter of fact, in the 5 years I had this vehicle, I have never heard the fans running. 

They wont turn on until the high side pressure reaches a threshold which from observation of my guage set is 150-200 psi, (this is probably temperature dependant) if the system has low pressure but not low enough to shut the system down the fans will not kick in.

 

When regassing the fans kicking in is the first indication (on a clutchless compressor system) that the system is starting to regrigerate correctly.

Not uncommon for radiator fans to not be working on at least one of their speeds.  Both should run simultaneously. 

My recollection is that on 9N Polo/Mk1 Fabia the on threshold for low speed fan action is 9 bar refrigerant pressure at G65 sensor, switch-off at 6.8 bar.

High/full speed fan action triggered on at 16 bar and off again at 12.  Some of the smaller fans are single speed, coming on with low speed main fan, staying on with full speed main fan.

 

Things are a bit different on recent cars with fan control module integrated into main fan and continuous speed control, but I believe both fans still run together at same speed when working right.

 

 

1 hour ago, Bertie90 said:

 

They don't turn on at all when I switch the AC on. I have never noticed that with the AC on I must admit, as a matter of fact, in the 5 years I had this vehicle, I have never heard the fans running. 

 

That's why your aircon failed on the hottest day of the year, check the fans spin freely and haven't seized, then check the fuses.

Your condenser was already very hot before you even started the car, as soon as you switched on the aircon the temperature would have shot up and with no fans running the ECU would have shut it down right away.

 

right so, I need to check the fuses for the fans, and look for any abnormalities in the wires/fans