AC Not Working

[KarlZ]

Hi Guys

First post for me!

After a bit of help - the Aircon compressor on my daughter’s 2013 Aygo has just been replaced and since then, the green light on the Aircon switch has not been working and the compressor clutch is not pulling in. The guy who replaced the compressor said he checked all the fuses around the instrument cluster and they are all ok. Does anyone have any wiring diagrams for the AC? Defo electrical problem.

Thanks in advance!

[flash22]

Has the system been regassed properly (you need the system running to set the correct pressures)

If the pressures are wrong, it will not turn on - was it vacuumed down and refilled correctly, new or used compressor ?

[KarlZ]

Hiya Flash22

The guy was an Aircon specialist, he had all the kit to re-gas the system. Reconditioned compressor fitted, then vac’d it down to make sure it was gas tight, then re-filled with the correct gas and oil. But he isn’t an auto electrician, he said there was an electrical issue preventing the system working. 

The reason for the compressor change was catastrophic pulley and clutch failure. The whole clutch assembly was spinning with the pulley and making a terrible noise. It Ripped the wire off the clutch body. So I wouldn’t be surprised if that has knackered something electrical by shorting out. But all fuses are OK.

My other thought is - is there a pressure switch somewhere that has been damaged or disconnected?

Haynes manual gives no wiring detail for the AC system, so wondered if anybody in the forum had access to this? I am electrically trained but not an auto electrician.

 

 

[Stivino]

If the green light doesn't come on, that can only be one of two things;

1, The bulb in the switch has blown.

2. There is no power going to the switch.

The green light only tells you that the bulb in the switch works, it tells you nothing about the A/C.

Before you start messing about with anything else, you need to check for power to the switch.

[KarlZ]

Thanks Stivino

That was the next stage, to check power. Haven’t started diagnosing yet, it could of course simply be the switch that failed at the same time as the compressor - I always think too complicated!

Again - if anybody has any wiring diagrams for it that would be excellent! 😉

 

[flash22]

Stranger things have happened, like the rear defrost and A/C switches being swapped (press the defrost button to turn the A/C on)

the A/C is controlled by the A/C amplifier, if wiring has been pulled it's likely a broken wire/connector that feeds the A/C clutch

 

The switch just tells the A/C amp to turn the system on

I have diagrams if required, check the 3 fuses 40a HTR, 10a Back-up and the 7.5a A/C fuse, Then the HTR relay and the wiring and connector by the compressor

[KarlZ]

Hi Flash thanks for that. Not sure what HTR relay is or where it is… 

would you mind sharing drawings?

thanks 😎

[flash22]

HTR relay feeds the A/C clutch

https://fuse-box.info/toyota/toyota-aygo-ab10-2005-2014-fuses-and-relay

Relay box No5. what's up under the dash (ignore the red arrow)

the A/C and HTR fuses are located on the rear of the dash, not the sides

Note. The blue and white relays (this is Relay box No.5) above the red circle (immobilizer)

 

 

[Stivino]

Forget all that.  The first thing you have to do is to find out why the switch won't illuminate.

[Stivino]

3 hours ago, flash22 said:

the rear defrost and A/C switches being swapped

Impossible, the multiplugs are not compatible.

[flash22]

6 minutes ago, Stivino said:

Impossible, the multiplugs are not compatible.

Correct, but you can physically move the switches and the caps still fit

I have come across many an oddity

 

another one was an issue with gear selection - turned out the OP had previous ankle surgery and wasn't pressing the clutch down all the way

[flash22]

19 minutes ago, Stivino said:

Forget all that.  The first thing you have to do is to find out why the switch won't illuminate.

The switch will not do a thing unless the HTR relay is energized, the A/C amp is powered, and the A/C pressure switch is closed

[KarlZ]

Guys, that’s a fantastic amount of info there, glad I posted. It’s much appreciated. Now I’ve got something to work with.
No light on the AC switch means the whole systems not being powered for some reason. Flash, you’ve given me more info on where the fuses are. I’ve been taking the Aircon specialist’s word for the fuses being ok so I’ll now take a look myself. 
 

I’ll post the fix if I get there. 
 

[flash22]

you can unplug the pressure switch and link it out, only do this for a short period of time tho

here are the fuses, 2 light green and 1 pink (square Jcase iirc)

[SimonIG10]

If there is no green light on the switch, I assume you have the fan on? The AC wont work without the fan running.

[KarlZ]

Thanks all for posting suggestions. I have sorted the issue so thought I’d update this thread for others to find out how I fixed it. 

It was simply the fuse on the bottom left of the speedo. F14 I think? One that IS listed in the Haynes Manual as supplying the AC. The Aircon specialist said he checked all the fuses there which is why I was looking for something more complex. But before I took the plugs off the back of the speedo to check the fuses on the rear, I thought I’d double check. So I feel a bit silly…

Story goes like this: AC button lights up but no AC. Pipes at ambient temp. System holds pressure (as found by pressing the Schrader valve and getting a face full!). Continuity check on the AC clutch revealed failed clutch. I have no means of dealing with AC gas so I tried a “hack” and swapped the clutch and pulley from a £40 eBay compressor. Worked for a while 🤩 then there was this almighty rattling from the engine. Pulley, Clutch and coil housing all spinning together, clutch wire ripped out of coil housing and probably shorted out hence, unknown to me, blowing the fuse. Paid an AC specialist to fit new compressor but he couldn’t test it because of an electrical issue. He “Checked” all the fuses he told me. He checked the system held pressure etc so should work if the electrical issue is fixed. But at least my daughter could drive it again, she doesn’t need AC in the UK winter! I eventually got round to investigating the electrical issue, and 5 minutes in, found this blown fuse. Replaced the fuse, all seems fine now. Clutch on the new compressor seems to pull in but when it’s 5deg ambient, it only pulses the clutch for about 5 sec every minute so without gauges I can’t tell properly if its working ok but the smaller pipe seems to get slightly warm so I guess it’s ok. 

Thanks again to all that contributed - this is what forums are for!

 

[flash22]

He checked the fuses, the ones in the engine bay, unless you know these cars you wouldn't know about the fuses around the gauges

 

thanks for the update

[KarlZ]

Nah he definitely checked the ones around the clocks. My wife had to look it up for him.