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Yaris TR 2010 - air con amplifier module exchange.


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Hi, Toyota dealer wanted £550 to swop my wife’s Yaris TR 2010 1.3ltr air con amplifier module for a new one, the part costs £491. I obtained the part number from Toyota and bought a used (but guaranteed) one online a lot cheaper. Is it a simple job for me to attempt.  PLEASE let me know how 😱Especially if you have swopped one.  Thank You 👍   

This diagram shows where it is supposed to go???

 

 

75520F2B-F9D3-421F-AAE9-57A5726C60B9.jpeg

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I am not an expert but have fixed my Avensis aircon and other cars. This looks like the cooler unit/heat exchanger so you would have to disconnect the (High pressure?) air con pipes first having de-pressurised the system safely. Quite nasty chemicals/flammable liquid are involved. You will have to remove a fair bit of the panelling under the wheel etc. The system will need filling again afterwards normally about £50 for a Yaris. They would also test the system for leaks before filling and will not fill if it is leaking.

Do- able as a DIY job but you would need to read up on how to do it. I am sure you will get good advice here on exactly how to do this-I will watch with interest.

I have found heaters and aircon to be quite tricky to fix as well as being hard to access.

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I would check if it has any gas, if it has you need a special tool to take the air out. Probably only use this tool once, but it is illegal to release this air. You would also have to learn how to read low and high pressure readings which you can learn on YouTube Scotty channel he does explain all this stuff. 

If you could get the tools second hand and go after market, maybe DIY.

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That looks more like the electronic control unit rather than anything related to the refrigerant circuit (such as the evaporator). If its the correct part number then swapping it should be straightforward although access is always the hardest part of any such jobs.

All you can do is try it and take it from there.  

 

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The A/C Amplifier is the electronic control module which controls the A/C compressor.

Replacement should be straightforward (plug and play). You might want to disconnect the Battery first.

On a RHD car it would be located to the right side of the HVAC air box. Approach from the driver's side footwell and remove the trim to the side of the clutch pedal.  

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Hi, Toyota had the car overnight, no leaks, compressor is ok, the told me it was the amplifier module ‘the brains behind the air conditioning’ as they called it. Just wondered if it was a 10 minute DIY job to exchange it???

 

thanks

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Once you have access to it then yes, a 10 minute job or less.

I would also advise disconnecting the Battery before unplugging and replacing the unit.

 

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UPDATE.  obtained a tested replacement air con amplifier from eBay, swopped it over today - still the same!!

Local, non Toyota dealer, garage said the car had an aircon pressure of 151bar 🤬  he suspects  it’s the aircon pressure sensor switch.  They are £225 from Toyota, but got a new one on line from AUTODOC, £56 including postage.

THE QUEST FOR COLD AIR CONDITIONING CONTINUES - anybody got the feeling that Toyota are fleecing their owners 🤬

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Wouldn't replacing the pressure switch require discharging of the refrigerant first? The pressure at rest for R134a refrigerant (compressor not running) should be approximately 70 PSI. (5 Bar) throughout the system on a warm day, and around 35 PSI at 5C. So 151 Bar (that's over 2000 PSI) is just crazy... not possible.

The pressure switches as far as I know simply operate in response to sufficient pressure (to protect against low refrigerant and/or cold temperatures) and to excess pressure. Whether they are N/O or N/C (normally open or normally closed) I don't know, however it would be a simple task to simply measure them in situ and apply the reverse to each in turn as a test. 

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18 hours ago, ToNo10 said:

UPDATE.  obtained a tested replacement air con amplifier from eBay, swopped it over today - still the same!!

Local, non Toyota dealer, garage said the car had an aircon pressure of 151bar 🤬  he suspects  it’s the aircon pressure sensor switch.  They are £225 from Toyota, but got a new one on line from AUTODOC, £56 including postage.

THE QUEST FOR COLD AIR CONDITIONING CONTINUES - anybody got the feeling that Toyota are fleecing their owners 🤬

Yes the Toyota price for a rear hub/ABS is £356 and a hub from a reputable after market seller is about £30. That is too big a difference for rip off not to be involved!

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That's still sky high though, its just not possible. The system couldn't withstand. When the system is OFF, the pressure is equally distributed in the system. Its a bit like an aerosol can. R134A gas has a precise pressure/temperature relationship.

If the readings was 121 PSI then its plausible if the engine (and so compressor) were very hot. 121 PSI  would be just over 8 Bar.

These show the pressure/temperature relationship and the pressure a manifold gauge would show at 5C and 21C ambient.

 

  

  

     

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Annotation 2019-07-03 150151.jpg

Edited by Mooly
Edit... replaced second image.
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The aircon pressure reading is obviously 121psi.  Sounds a tad high for a resting system but ok.

Don't throw parts at the car in the hope of fixing it. Do some diagnostics first. If the pressure switch is suspect then it can be checked with a meter and/or jumped-out to run up the system. I'm surprised the a/c 'shop didn't do that. Verify the old part is faulty before replacing.

Honestly, if the system is holding gas then diagnostics should be fairly straightforward. The control system is not that complicated. Its small gas leaks that are the bane of A/C.

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Thank you all for advising 👍

next week I will receive a new air con pressure switch and get it swopped - here’s hoping !

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17 hours ago, ToNo10 said:

Thank you all for advising 👍

next week I will receive a new air con pressure switch and get it swopped - here’s hoping !

I would urge you not to replace it unless it is proven to be faulty. When you change it the system has to be evacuated, then opened up then regassed again.

If you unplug the pressure switch you can check it for continuity using a multimeter on the pins. You could also use a bit of thin wire inserted into the plug contacts to simulate a closed pressure switch. The system should then operate normally. There is no risk of damage because you know there is plenty of pressure in the system.  If the system still doesn't run then you need to look at the feed to the compressor (relay fault?).  Now you know there is enough gas in the sytem you should be able to diagnose the fault with a multimeter.

Incidentally, if its a three-pin Denso pressure switch with M10 fitting you might like to know that the wholesale price to distributors is under £7 each. They are used on a huge range of Toyota/Lexus and other marques. Gives you an idea of the obscene mark-up on Toyota parts!

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Thank you for your advice, I will try the multimeter and clip shorting and see what happens.

Should there be a continuity beep (short circuit) on the pressure sensor pins or not?

* THREE wires to sensor cap, which should be shorted out?  Thank you.

 

 

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Three wires point to the switch being a 'trinary' type. This would typically have a low and high pressure switch that are in series, combined together with a switch for the fan. If you search for Trinary switches you'll see most are actually four wire types.

Disclaimer... my background is electronics, not air con but this is how I imagine it will be configured.

The three wire one will have a common connection which could be either ground or 12 volt supply, you will have to determine that by measurement. One way might be to measure the voltage on the three wires and see if any one of them has +12 volt present while the other two have no voltage present. If it is configured like that then you could then measure continuity from the common terminal of the switch to the other two connectors and see if each reads essentially zero ohms (short circuit).

 

 

 

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SOLVED!!!.....

It WAS the aircon pressure switch/sensor, our local one man band garage swopped it FREE OF CHARGE (I gave him £40) and it is working! 🤗  The local Toyota dealer had the car all of on day, kept it overnight ‘for diagnostic purposes’ and said it was the aircon amplifier.  Local guy swopped that for one I got off eBay no difference.  Local guy said....”there is excessive pressure in the system, I bet it’s the pressure sensor”  and it was!

..... thanks to those who replied and advised me on this forum, it is appreciated 👌

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Thank you 🙏 

bottom line...

Toyota wanted £491 for a aircon amplifier module (which it wasn’t)

plus £225 for a aircon sensor/pressure switch.

PLUS LABOUR.

In actuality it cost us....

Aircon amplifier from eBay £34.99

Aircon sensor/pressure switch. £56

£40 Labour 🤗🤗🤗

 

 

 

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That's a much better outcome Tony.

I take it you won't be gracing that Toyota dealer with your presence again?😟

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