Is it the AC-compressor?

[anonymm]

Hello good people!

I live in Norway, which is cold most of the year, so the fact that Air Conditioning doesn't work is not something you think about other than one short period in the summer. So, I've been having this problem for a few years, but not done anything about it... yet...

My car is a 2005 Toyota Avensis, with the 1,8l petrol engine. (And the type of AC/Heating system that has the digital display, not the rotary switches)

Here's what I know:

-AC doesn't blow cooled air. It dssapeared on the left side of the cabin first and then on both sides.

-I have had the coolant changed and that is with dye, so I should see leaks. I am sure there are no leaks.

-All duct doors that should open and close are working. I have opened the interior of the car and looked at all of them. Even removed servos and tried to open and close them manually.

-This model doesn't have the traditional electromagnetic clutch that engages and disengages the AC-compressor, instead it's a "variable displacement"-compressor with a solenoid that changes the position of a disc inside of the compressor.

-With the plug connected to the solenoid, I measure 12V on the wire that supplies the solenoid when AC is turned on in the cabin, and 0V when AC is turned off.

-This leads me to believe that the solenoid is not working. (It gets voltage but nothing happens). In other words: Replace the complete compressor and it should work.

-I called a Toyota-workshop and talked to a guy who at least sounded like he knew this stuff. He told me to double-check it by the following test: Take the drive belt off the pulley on the compressor. The pulley should be easy to turn. Feed 12V directly to the solenoid and try to turn the pulley again, it should be harder to rotate. I tried this and felt absolutely no difference.

 

So my questions are:

-Does anyone disagree that replacing the compressor would fix the problem?

-I have read that you shouldn't drive a car with this type of compressor when you don't have coolant in the system. I am guessing this is because the coolant also contains lubricant, and since the compressor is always rotating, there will be mechanical wear to it without lubrication. DOES ANYBODY HAVE AN IDEA HOW FAR IT WOULD BE SAFE TO DRIVE THE CAR WITHOUT COOLANT, BEFORE THE COMPRESSOR IS COMPLETELY DESTROYED? I am asking this because I am considering replacing the compressor myself, then driving to the nearest workshop to have the system filled with refrigerant.

-If the answer to the last question is "Not far at all", I am thinking that I could buy a shorter drive belt to put on, so that I can drive the car a little without the compressor rotating. Will a drive belt for cars without AC fit if over all the components except the AC-compressor?

 

Thank you so much for any answer!

[Stivino]

The compressor pulley turns when the engine is running but, it's only the pulley that's turning.  The internals of the compressor don't turn until you switch it on and even then, the internals won't turn if there is no gas in the system because there is a pressure switch, which if it doesn't detect pressure in the system, won't allow the system to run.

So, you can drive the car to the moon and back, if you so wish.

[anonymm]

That would be true if this one had a clutch. But since it doesn't, the internals in the compressor turns all the time

Watch this youtube-video to see the difference:

 

[anonymm]

It is important to notice that this is a variable displacement compressor, not a fixed displacement one, which is more common.,

[Stivino]

8 minutes ago, anonymm said:

It is important to notice that this is a variable displacement compressor, not a fixed displacement one, which is more common.,

Thanks, I should have read your first post properly.

As I understand it, your system also has a fail-safe system to ensure constant lubrication so, the same rules apply with regards to being able to drive the car.

[Mooly]

4 hours ago, anonymm said:

-AC doesn't blow cooled air. It dssapeared on the left side of the cabin first and then on both sides.

-I have had the coolant changed and that is with dye, so I should see leaks. I am sure there are no leaks.

So it worked OK for a while after a re-gas and then failed in the manner you describe? The compressor must be running to blow cold on one side, the effect of cooling disappearing from one vent before the other has been reported before as being symptomatic of low charge.

Yes, it could be the compressor leaking but that wouldn't automatically be the first suspect. Your description (to me) suggests a slow loss of refrigerant charge and that isn't always easy to see, even with UV dye in the system. A leaky condenser or pipework would be more likely I think. Something much smaller than a pin hole is all that is needed to allow the gas to escape over a few days.    

[flash22]

Get an a/c guy to look at it rather than throwing parts at it, 2005 I would think the condenser/dryer is past its prime

If it has had dye in the last charge then an uv light should pick it up but if there is no charge its useless, it needs gauges put on it to see what charge is in the system, then a vacuum pulled, it's not a diy job imho

[anonymm]

2 hours ago, Stivino said:

48 minutes ago, Mooly said:

So it worked OK for a while after a re-gas and then failed in the manner you describe? The compressor must be running to blow cold on one side, the effect of cooling disappearing from one vent before the other has been reported before as being symptomatic of low charge.

Yes, it could be the compressor leaking but that wouldn't automatically be the first suspect. Your description (to me) suggests a slow loss of refrigerant charge and that isn't always easy to see, even with UV dye in the system. A leaky condenser or pipework would be more likely I think. Something much smaller than a pin hole is all that is needed to allow the gas to escape over a few days.    
 

 

No, after regassing it has not worked at all.

Not even the first hour aftrr regassing.

 What I described about losing cool air on one side happened BEFORE I tried regassing.

I have not meassured if there is pressure in the system (I do not have the right equipment accessible). But I have pushed down on that spring-loaded thing in the middle of where the pressure gauge should be connected (with the tip of a screw driver) - just for a split second and I clearly heard gas under pressure escape with an audible PFFFFT sound. So I don,t really believe that there is any leaks 

[mrfixer]

Get an AC technician to put gauges on it. By looking at the high-side and low-side pressures you'll quickly see if the compressor is doing anything.  It should be safe to drive because a fair amount of oil aways remains in the compressor.

If the compressor is faulty then get the AC technician to vacuum out the gas. Then you can do the compressor swap. Frankly I would let the AC technician swap the compressor - there is not much work involved. You'll need him to regas it for you anyway.

[anonymm]

I believe that since I payed a workshop to "service the ac", which basically means changing the gas, this must include a test with pressure gauges (?)

 

It would be interesting to hear if anybody agrees that I should feel a difference when trying to rotate the pulley with and without 12V on the solenoidm

[Mooly]

Just blipping the valve shows there is pressure in there but that is not definitive proof the system is fully charged... it could be like an 'empty' aerosol can, still a bit of pressure but no liquid refrigerant under pressure. Usually a recovery machine will be able to give a readout of the refrigerant recovered from the system when a re-gas is performed.

I owned an Audio A4 years ago that developed a leaky evaporator and would not run at all, however the system still had lots of pressure when blipping the service port valves. Subjectively it sounded a lot more than blipping a tyre valve for example.

Also if you blip the valve then you should get the equivalent of 'Freezer Spray' coming out which would be around -30C or so. It should be that cold it burns you. R134a is exactly the same stuff used from aerosol cans for electronics fault diagnosis which I use. As soon as you vent any to the atmosphere it 'boils' off at that low temperature.  

mrfixer is correct on the use of manifold gauges, they will tell you all you need to know in seconds, not just the pressure when its not running but also the pressures when operating.

I've no idea on the compressor and turning it slowly by hand tbh. It may be much easier to turn than you think at such slow speed. 

[anonymm]

16 hours ago, Mooly said:

I've no idea on the compressor and turning it slowly by hand tbh. It may be much easier to turn than you think at such slow speed. 

Shouldn't there at least be some sound as I turned the voltage on and off? I did this in a completely silent place, even turned off the radio to be sure I could hear if there was any sound. Supplying voltage should make something move in there, right? So I would thing that some faint sound at least should be possible to hear... I turned the voltage on and off several times...

[Mooly]

So I've had to do a bit of reading of up on how these actually work and it seems the '12 v' feed is more than just a simple voltage command. The signal is called a PWM or pulse width modulated signal which means that the voltage changes quickly (very very) between 0 and 12. That in itself could give a misleading result on a normal multimeter, you would need an oscilloscope to look at the drive signal.

Have a look down this page:

https://www.motor.com/magazine-summary/diagnosing-variable-displacement-compressors/

So based on this you would not hear any kind of 'click' on or off as you apply this PWM signal. You might hear a faint high pitched noise. In the text on that page a period of 2ms is mentioned. That is a frequency of 500Hz which is close to middle C on a piano in pitch. So you may hear something more like that rather than a click.

 

 

 

[anonymm]

Thank you, Mooly. That article was very informative. You have strenghtened my suspicion that the guy I talked to at Toyota knows a lot, but not everythinh.

[Konrad C]

There is a basic test that can be done - http://www.cardiagnostics.be/-now/Self Diagnose Toyota Corolla ECC-panel.htm

[anonymm]

37 minutes ago, Konrad C said:

There is a basic test that can be done - http://www.cardiagnostics.be/-now/Self Diagnose Toyota Corolla ECC-panel.htm

This is not the type of climate control panel that I have, but I have done a similar test fot my model. It gives me no usefull information. Can't remember exactly what it tells me right now, somthing like sunlight sensor not working or something. But from what I could read on some forums, it always shows that and it really doesn't mean anything....

[mrfixer]

Anonymm

I am largely retired now but I have over 30 years experience in the motor trade, buying/selling/repairing cars.  Believe me when I say that you won't get far fixing an AC system without at least pressure gauges and some experience.  For example your problem could be a faulty pressure switch, which would shut down the system. 

I know car repairs are very expensive in Norway, but AC faults do not respond well to a 'poke and hope' approach. You have to use a technician. 

[Mooly]

I have to agree with mrfixer, fault diagnosis is all about gathering information and a couple of minutes with a manifold gauge set will show both static resting pressure (and so indicate the state of charge) and also dynamic pressures as the system runs. It tells you so much. 

[anonymm]

It is very much possible that you are right. But on the other hand, I think it's really interesting to learn how stuff works.

I was really sure that I was right that it was the solenoid on the compressor that was broken. It seemed like a simple thing - I gave it the right voltage, but nothing happened. But I learned a lot from reading that article that one of you linked to. Two important points especially: That these compressors have a "safety device" that will break off and disconnect the pulley from the shaft if there should be a mechanical seize-up internally in the compressor - AND - how it is controlled by that pulsating DC-voltage.

Yesterday I was able to test that both of those things are in order. I took off the drive belt from the pulley. Then I started the engine. With the AC-button off, I could turn the pulley with almost 0% resistance. Then I switched it ON. The resistance when I tried to turn the pulley by hand was at once different. It was easy to feel that there were more resistance. So clearly A: The pulley is connected to the driveshaft of the compressor and B: When the solenoid gets the correct signal, parts are moving inside the compressor.

So, I began feeling 90% sure that I knew what the problem was. Now I'm 100% sure that I don't! Thankfully I haven't spent any money on it.

[mrfixer]

If you are determined to work on it yourself then I suggest you get a set of AC pressure gauges. In the UK we can buy these from £30-40 from Amazon, eBay etc.   Once you know the pressures it becomes possible to make a diagnosis.  Note that it is illegal to release gas into the atmosphere though....

From what you have described I think you will find that its either low gas or a faulty pressure switch.

[anonymm]

I don't really know what I'll do.... Have to think about it for a while...

 

Could you give me a link to the correct type of pressure gauges that I would need? 

Is it possible to say what type of threads or connector they have? Because I have access to all types of pressure gauges for free, but not with the right connection to fit.

What pressure ranges are we talking about?

[Mooly]

Pressures on the high and low side should be around 70 PSI with it off (warmish ambient temperatures). If its lower than that then the charge is low.

When running correctly you would see around 35 PSI on the low side and around 180 PSI on the high side, if the charge was low but the system still ran you would see these figures both fall a little, say 20-25 and 150-160 ish and if really low on charge they would be lower still. Ambient temperatures do play a big part though.

Seems there are a lot of images for this... do an image search for 'R134a system pressure'.

The gauges you want are called 'Manifold Gauges' and are specifically designed for air con work but please bear in mind that spending money on this gear doesn't get you a working system, you still have to fix or have fixed the original problem and then have the system properly evacuated (vacuumed down) and recharged. Again lots of images for these. Proper manifold gauges will allow the air in the connecting pipe work to be purged before fresh refrigerant is introduced.

They look like this (no idea on the quality)

https://www.amazon.co.uk/KKmoon-Refrigerant-Manifold-Gauge-Conditioning/dp/B07DPCZBWG/ref=pd_sbs_60_2/262-3986127-1482935?_encoding=UTF8&pd_rd_i=B07DPCZBWG&pd_rd_r=75f278e8-b27e-4fa8-8cad-fe2fecdc6842&pd_rd_w=6UlRM&pd_rd_wg=UuLAZ&pf_rd_p=2773aa8e-42c5-4dbe-bda8-5cdf226aa078&pf_rd_r=GKTCPK43BTMY3FQNWHKH&psc=1&refRID=GKTCPK43BTMY3FQNWHKH

 

 

 

 

 

[anonymm]

I have actually learned a lot from your posts here, guys!

In case somebody else with similar issues comes across this thread in their search for answers, I would like to tell how it all ended.

I took the car to a Toyota-dealer/workshop and told them to first check if the pressure is correct, then check all related electronics, pressure switches, temperature sensors and so on.

Their conclusion was that the pressure was too low. Everything else was as it should be. The pressure was messured at 9 bar, when it should be between 11,7 and 15,7 or something like that. (sorry for using bar, but PSI is as un-understandable to me as bar is to you  🙂    ).  New gas was added to correct pressure and it worked fine! Possibly the other workshop that I used to re-gas it three years ago had done something wrong.

I was really happy about this, until, three days later, I suddenly noticed that it was no longer working properly. I mean it works, but not 100%. There is a noticeable reduction in its ability to cool on the hotter days.

So, I took it back to the Toyota-shop to check for leaks and a small leak was identified at the bottom of the radiator in the front, which I am going to have them repair.

Thinking back to three years ago, when I had it re-gassed for the first time, I honestly felt like it didn't work at all, but I do remember that I saw water under the car when it was parked on a hot day... So, if the other workshop actually did make a mistake, as I suspected at first, I am not so sure about anymore. But anyway, that's how it all went and I hope and believe that this will fix the problem permanently.

[Stivino]

Water under a car after the A/C has been on is normal.  It's condensation from the evaporator, it runs down a wee pipe and evacuates under the car.

[microwave1965]

I hope you got it all sorted in the end anonymm.

I have the same car as you and had same issue. I had it regassed, after passing the vacuum test but after a few weeks, it wasn't as good as before.

The technician couldn't find any leak on the condenser, the usual suspect. He eventually found a tiny little hole in the aluminium pipe that runs across the rear of the engine bay, under the plastic pipe securing clip. I sourced a second hand replacement pipe and he came back, replaced the pipe, retested the system before re-gassing. Problem fixed and still it's good 3 years later.

Not in a million years did I suspect a solid metal pipe to leak like that.