How To Test Air Conditioning Pump?

[Dmitriy]

Hi All,

Air conditioning does not seem to kick in at all

in my Avensis 1.8L VVT-i made in 2000 (engine 1ZZ-FE):

when I press the button there's no impact on the

engine's rpm. Adding the gas into the system did not

help even though the system appears to hold the required

gas pressure.

While going through the posts at this forum I came across

one that suggests connecting +12VDC from the Battery

directly (i.e. bypassing all sensors etc) to where a

black wire connects to the pump in order to test it.

The only black wire I can see going to my pump looks

more like the ground wire as it seems to attach directly

to the pump's body.

If this is a valid method of testing the pump can someone

please help me locate the right contact on the pump which

to apply +12VDC to?

Many thanks in advance,

Dmitriy

[Nightstalker]

Hi All,

Air conditioning does not seem to kick in at all

in my Avensis 1.8L VVT-i made in 2000 (engine 1ZZ-FE):

when I press the button there's no impact on the

engine's rpm. Adding the gas into the system did not

help even though the system appears to hold the required

gas pressure.

While going through the posts at this forum I came across

one that suggests connecting +12VDC from the battery

directly (i.e. bypassing all sensors etc) to where a

black wire connects to the pump in order to test it.

The only black wire I can see going to my pump looks

more like the ground wire as it seems to attach directly

to the pump's body.

If this is a valid method of testing the pump can someone

please help me locate the right contact on the pump which

to apply +12VDC to?

Many thanks in advance,

Dmitriy

hey Dmitriy....

I had an issue on my landcruisers aircon where it did not kick in, the aircon light would flash... does yours do the same?

My local MR T ended up replacing the aircon pump and all worked again...

Regards

Rob

[Dmitriy]

Hi Rob,

hey Dmitriy....

I had an issue on my landcruisers aircon where it did not kick in, the aircon light would flash... does yours do the same?

My local MR T ended up replacing the aircon pump and all worked again...

Regards

Rob

Thanks for your reply. No my aircon light goes on when I press the button once, and then goes off when I press it again. It does not flash.

Prior to replacing the pump I would like to make sure it's the pump that does not work and not a fuse or a sensor that breaks the circuit.

Best Regards,

D.

[Mooly]

I'm not familiar with the Avensis but the A/C compressor normally has an electromagnetic clutch that is fed with 12 volts to engage it.

If so you should be able to locate a wire going to the front of the compressor where the pulley is. When the A/C kicks in you should be able to measure 12 volts on it. The compressor normally doesn't run all the time but cycles on and off with demand so don't just overide it.

You also normally hear the clutch click as it keeps engaging.

Another crazy thought with you saying the revs don't alter... is it worth disconnecting the Battery for a while to give everything a "reset". You will have to reprogram your one touch on the windows by holding the button for a few seconds after winding the window up.

[Dmitriy]

Hi Mooly,

I'm not familiar with the Avensis but the A/C compressor normally has an electromagnetic clutch that is fed with 12 volts to engage it.

If so you should be able to locate a wire going to the front of the compressor where the pulley is. When the A/C kicks in you should be able to measure 12 volts on it. The compressor normally doesn't run all the time but cycles on and off with demand so don't just overide it.

You also normally hear the clutch click as it keeps engaging.

Another crazy thought with you saying the revs don't alter... is it worth disconnecting the battery for a while to give everything a "reset". You will have to reprogram your one touch on the windows by holding the button for a few seconds after winding the window up.

Thanks for your reply. One of the cables does go to a connector near the pulley indeed. I'll try measuring the voltage there once I find the right 2 "control" wires. By the way what did you mean saying "don't just override it"?

Also could you please expand on reprogramming my one touch on the windows? I already disconnected and connected the Battery (and discovered a loose joint, which explained why the clock etc reset a few times during the recent past) and the alarm still works... Do you have a link to the exact procedure to follow?

Many thanks,

Dmitriy

[Roker]

The AC pump is a variable vane type, it does not have a clutch that clicks in

[Dmitriy]

Hi Roker,

The AC pump is a variable vane type, it does not have a clutch that clicks in

Any ideas how to check if it's alive anyway? (without removing it)

Thanks in advance,

Dmitriy

[Roker]

All I can suggest is to feel the pipe (the large one) comming from the bulkhead to the pump, if it is working this should be cold. But it could also be out of refigerant, there is a common fault where the 8 mm aluminium tube leaks on the bend under the Battery and drips onto the under tray

[Dmitriy]

Neither of the pipes feels cold, which is no surprise if the pump does not kick in.

In fact I tried adding gas already up to the required pressure and the system seems to keep it. Still no luck.

[t-spiritpete]

Hi All,

Air conditioning does not seem to kick in at all

in my Avensis 1.8L VVT-i made in 2000 (engine 1ZZ-FE):

when I press the button there's no impact on the

engine's rpm. Adding the gas into the system did not

help even though the system appears to hold the required

gas pressure.

While going through the posts at this forum I came across

one that suggests connecting +12VDC from the battery

directly (i.e. bypassing all sensors etc) to where a

black wire connects to the pump in order to test it.

The only black wire I can see going to my pump looks

more like the ground wire as it seems to attach directly

to the pump's body.

If this is a valid method of testing the pump can someone

please help me locate the right contact on the pump which

to apply +12VDC to?

Many thanks in advance,

Dmitriy

Hi mate, I have attached some info that may help.

Pete.

[Dmitriy]

Hi Pete,

Hi mate, I have attached some info that may help.

Pete.

Thanks a lot for the diagrams. They seem to come from the Avensis Mk2 (2003 - 200x) manual.

Do you know if its a/c system is the same as in Avensis Mk1 (1998 - 2002)?

Dmitriy

[Dmitriy]

I have just located the black wire in black shield that goes from the 3-pin connector in the middle of the compressor body to the 2-pin connector next at the pulley (another black wire coming to the same 2-pin connector is apparently ground). Now wondering what should happen if I connect +12VDC (or some other voltage?) directly to that shielded black wire in an attempt to simulate the ON signal bypassing all sensors?

[Dmitriy]

OK when I supply +12VDC directly from the Battery to the positive contact in the connector at the pulley I do hear a click - this is when ignition is OFF. When ignition is ON and engine running this DOES make the compressor shaft rotate together with the pulley: unlike before the engine rpms now clearly drop and I can see the inner part of the pulley that the shaft attaches to spinning together with the outer part led by the belt. So we know that the compressor does work when told to. Also one of the pipes is quite hot but the other has not become any colder within the first 5 minutes of such forced AC operation. Just to remind that I did add gas recently up to the recommended pressure.

Now question: why is it apparently not told to? Pressure switch fault? (assuming there are no leaks and the pressure is still correct).

[igormus]

OK when I supply +12VDC directly from the battery to the positive contact in the connector at the pulley I do hear a click - this is when ignition is OFF. When ignition is ON and engine running this DOES make the compressor shaft rotate together with the pulley: unlike before the engine rpms now clearly drop and I can see the inner part of the pulley that the shaft attaches to spinning together with the outer part led by the belt. So we know that the compressor does work when told to. Also one of the pipes is quite hot but the other has not become any colder within the first 5 minutes of such forced AC operation. Just to remind that I did add gas recently up to the recommended pressure.

Now question: why is it apparently not told to? Pressure switch fault? (assuming there are no leaks and the pressure is still correct).

Hi Dmitriy

As far as I ve caught you after have re-gased the system has become operative ? ANd it is clear that delivery tube is hot and wise. As visible you have an issue with air inside the system and this air creates water that is being frozen exactly after throttle valve before eveporator. Before re-gasing -- it would be fine to have the system vacuumed and remain it for a while to see on the vacuum gauge. If the vacuum remains the constant then you have no leaks and wise. The vacuum is highly required before re-gasing too prevent moisture be dropped converting into an ice after throttle valve. The main task of the pressure sensor is exactly to switch compressor coupling OFF in case of an icing after throttle valve and safe the system from explosion. Check step by step: vacuum and performance of this switch. Cheers/Igor

[Jamesbelfast]

The amount of refrigerent in the system is determined by weight NOT by pressure.

Also if the system under or over-pressurises it wil cease operating. This is a safety feature to prevent damage. A faulty receiver/dryer wil also prevent the system from chilling. Obviously if the system has a high water vapour content the receiver/dryer will not be able to cope.

The compressor is activated via an electro-magnetic clutch.

A variable compressor is designed so it can run at a constant speed but vary its output.

For those interested the link below shows how a variable displacement A/C compressir works.

http://www.polarbearinc.com/Articles/Variable%20Displacement%20Compressor.pdf

[Dmitriy]

Hi Igor,

Hi James,

Many thanks for your valuable comments and the pdf: you both turned out to be right. I also eventually suspected issues with air in the system and have just got it properly recharged at a local Kwik-Fit for £49 (a 45-minute job done automatically using Robinair CoolTech Coolant Exchanger) as could not find how to vacuum it on my own. AC runs OK now, and it was great to learn that my AC compressor is not faulty.

For those interested in how AC works I found this video useful, partly because it shows the internals of the AC compressor (in fact there are plenty of others):

Just one question left now: it then follows that the recharge kits like Ez-Chill R-134a by Interdynamics sold at Halfords etc are only useful when not too much air entered the system?

Cheers,

Dmitriy

[Jamesbelfast]

In my opinion and experience these refill kits should be banned as they soon may be under impending envoronmental legislation.

Firstly they are misleading in making people think that pressure is how to determine how much refrigerant should be in an air-con system.

Secondly I have heard horror stories whereby owners have had to have expensive repairs carried out afterwards. Has anyone estimated the cost of air-con repairs recently.

Thirdly the disposal of air-con refrigerant is strictly controlled by law.

[Roker]

Thanks jamesbelfas: Note that your diagram says it has no clutch, a lot of people keep say to check it by engaging the clutch. I looked into this with my Avensis, the spec says Variable vain compressor, it also says it will be damaged if you allow a refigerant leak to empty the system. This is because there is no lubrication to the permanently engaged compressor if there is no refrigerant.

To the best of my knowledge it is the old type refrrgerant that is controlled by law, the new type is enviromentally friendly.