XP130 2016 1.4 d-4d Air Conditioning Fault

[rich1e2001]

The air conditioning on my (new to me) mk3 1.4 d-4d doesn't seem to be working.  I've checked the low side gas pressure with one of those DIY refill kits (and slightly topped it up) but this didn't resolve the issue. I've checked the voltage on the solenoid feed from the ECU and it's giving me ~7.84v regardless of AC control button being on of off.  This seems a bit strange to me; does anyone happen to know what voltage to expect here?  I had assume it would be 0c or 12v.  Can I prove the pump and simulate control voltage by applying 12v direct to the solenoid terminals or is this likely to damage something?  Conscious these systems also look at the high side pressure and feeds this back to ecu.  When I measure resistance on the AC pressure sensor I get ~5kOhm and ~11kOhm on each side of the 3 pin sensor. 

Lastly, on my other cars I've usually been able to hear the AC pump spinning when engaged but having never had this one operational I'm also look for confirmation that this one is similarly obvious to hear when the AC is turned on?  

 

Thanks in advance!

[flash22]

Toyota AC pumps are constant drive with an internal clutch, do you have manual AC or climate (LCD on the controls) ?

Does the fan work ? Does the blend doors operate ?

[rich1e2001]

Its manual AC, no LCD on the controls. The fans and heater work just fine, not sure how to check the blend door but varying the temp control from warm to cool does affect change as far as I can tell, just the cool minimum temp is ambient.  I can stick a probe in it for reading though if that's helpful. 

[flash22]

If its manual AC the blend doors and flaps are all mechanical, tbh you need techstream to talk to the AC amplifier/HVAC to see if it has any codes a scan tool maybe able to talk to it too to see if it has any B14xx or U01xx codes

does the light come on when you press the AC button

[rich1e2001]

Ok, that's a good steer thanks.  I was just starting to look into setting up techstream and wondering if it was compatible with this era of car so that's really useful to know as well.  Will look into that further.

1 hour ago, flash22 said:

does the light come on when you press the AC button

Yes the AC button does light up as normal when pressed on.

When the system is running, should I be able to hear an audible difference when the internal clutch is engaged / disengaged?

I may end up wheeling it over to Toyota in the end, but will investigate a bit further first I think.

[flash22]

I would have an AC specialist look at it and check the high and low sides properly

you could try disconnecting the Battery for 15 min's and let the ecu's reset

[rich1e2001]

2 hours ago, flash22 said:

try disconnecting the battery for 15 min's and let the ecu's reset

I gave this a try as it seemed like a sensible next step, but no luck unfortunately. If only it were as simple as that!

Got some progress however with the OBDII scan after trying a couple of different apps. 'Car Scanner' on play store with ELM327 wifi OBDII dongle worked in the end:

B1423
Raw code: 9423
ECU: Climate/Heater
Status: Confirmed
Toyota: Open in pressure Sensor Circuit / Abnormal refrigerant Pressure (Progr, RX3)

Like you said, seems like a trip to the specialist to have those pressures measured accurately and take it from there.  Will let you know how it goes, thanks!

[stantheman1]

When you tried topping it up was it reading a very low pressure and can you remember what it was?

[flash22]

A quick look shows B1423 open or closed short

looking at your results above 5k and 11k ohm seem out of spec, Denso switch is £25 but needs the system evacuated to fit it

[stantheman1]

Would it not show open cct/ high resistance when the pressure was too low?

[rich1e2001]

15 hours ago, stantheman1 said:

When you tried topping it up was it reading a very low pressure and can you remember what it was?

It's topped up on the low pressure side which was reading pretty low, but not empty. The conundrum (at least to me!) is that the pressure is read by the car on the high pressure side so if the pump isn't engaged/spinning, I don't see how the high pressure side is ever going to see this regardless of any change to the low side. That might just be my misunderstanding of how this pump works though.

[rich1e2001]

13 hours ago, flash22 said:

looking at your results above 5k and 11k ohm seem out of spec, Denso switch is £25 but needs the system evacuated to fit it

I was thinking along the same lines; if it was just a case of swapping it, for all they cost it would be worth putting in a known good one and ruling this out, but needing to discharge this system is a problem for me and therefor will need to get it booked in with someone who has the equipment.  I'm not convinced that when I'm measuring the resistances this is the correct way to interrogate it. It's a 3 pin sensor, +ve, -ve and presumably read out pin.  I guess it could be a 5-20mA current loop output it generates, like other pressure transducers I've seen (admittedly not in automotive though).

[flash22]

You can check the sensor voltage at the AC amplifier, its a standard 3 wire sensor 5v, signal and neg

to test the sensor on its own you need a 5v load across 1 and 3 and read the voltage between neg and pin 2

I can pull the info if required

[rich1e2001]

Thanks for all the responses. 

So owing to time constraints and being fairly sure it wasn't something I could repair myself in any case (i.e. I don't have the equipment to discharge the system), I ran it to my local garage.  The mechanic simply recharged the system and it's up and running great now.  I couldn't speak directly to him as he was on another job when I turned up to collect it but from what I can tell they filled it, stuck some dye in and proved nothing obvious leaking from it.  I guess either he had some way to increase the pressure on the high pressure side (letting the pressure sensor see the minimum needed so the controller would then start engaging the compressor clutch again) or my  DIY refill kit is no-where near accurate and I wasn't achieving the minimum pressure needed when topping up the low pressure side.  Bit of a non-event in the end but I suppose at least it was a low cost fix and hopefully this info is of some help to anyone else who comes across this issue / error code.

[Cyker]

Not to be a downer, but keep an eye on the system - It should easily last a year if not two with no noticeable drop in cooling performance. If it starts going before even a year is up, you need to find someone who can check the system properly.

99% of garages just rely on the machine to do everything and have no AC diagnostic ability, and as I've discovered, just because the machine can't detect any leaks doesn't mean there are no leaks.

My Mk2's AC system was refilled 3 times as part of AC diagnostics in just over 6 months, and every time the AC machines gave it a clean bill of health, when clearly there was something very wrong and leaky!

 

[flash22]

1 hour ago, Cyker said:

Not to be a downer, but keep an eye on the system - It should easily last a year if not two with no noticeable drop in cooling performance. If it starts going before even a year is up, you need to find someone who can check the system properly.

99% of garages just rely on the machine to do everything and have no AC diagnostic ability, and as I've discovered, just because the machine can't detect any leaks doesn't mean there are no leaks.

My Mk2's AC system was refilled 3 times as part of AC diagnostics in just over 6 months, and every time the AC machines gave it a clean bill of health, when clearly there was something very wrong and leaky!

 

They did it properly they put a UV tracer in, a black light will show it up any leaks otherwise they should have a sniffer

 

As they say, the tool is only as good as the person(s) using it thats why you get someone that does it daily, You don't go to a proctologist to get your teeth cleaned do you

[Cyker]

In the case of my Mk2, there was no visible UV dye anyone could find, except where it had sprayed on part of the crashbar from an earlier condenser replacement - I guess when the leaks are tiny but numerous it doesn't show up so well? Even the couple of places that had a sniffer couldn't find anything conclusive, just that there was a leak somewhere... (No excrement Holmes...!)

 

[rich1e2001]

14 hours ago, Cyker said:

Not to be a downer, but keep an eye on the system - It should easily last a year if not two with no noticeable drop in cooling performance. If it starts going before even a year is up, you need to find someone who can check the system properly.

99% of garages just rely on the machine to do everything and have no AC diagnostic ability, and as I've discovered, just because the machine can't detect any leaks doesn't mean there are no leaks.

My Mk2's AC system was refilled 3 times as part of AC diagnostics in just over 6 months, and every time the AC machines gave it a clean bill of health, when clearly there was something very wrong and leaky!

 

Thanks for advice, the garage offered to check it again with the UV light after a week of use to see if anything obvious has appeared.  I will have done about 300-ish miles in it by then so will run it round to them on Monday for another check and let you know if they find anything interesting. It's taken 5 years to deplete to this point so if I got another 5 years before recharging I wouldn't be too upset at that, fingers crossed.  I guess I could treat myself to a set of AC gauges and just periodically check the pressures, I guess that would more robustly rule out any leaks.

[rich1e2001]

Just to follow up on this, I had the same problem re-occur this month. Knowing it was probably the gas pressure, I tried topping up the low pressure side with the home top up kit.  I realised after the first attempt that the engine should be running and spinning the AC pump for this to have any effect!  Low and behold, after about 1/4 bottle (?) of R-134a (the Halfords stuff in the green bottle) its working a treat again. I think it must have a minor leak somewhere but at ~18 month top up frequency, it's probably not worth worrying about unless it gets significantly worse in the coming years. 

[Max_Headroom]

21 hours ago, rich1e2001 said:

I think it must have a minor leak somewhere but at ~18 month top up frequency, it's probably not worth worrying about unless it gets significantly worse in the coming years. 

If its leaking into the car it may be something to worry about!

[rich1e2001]

19 hours ago, Max_Headroom said:

If its leaking into the car it may be something to worry about!

Its pretty much non-toxic and in such dilute, miniscule quantities it's never going to get to the level of concentration you'd be worried about.