Air Con unit

Migliore

Junior Member
Messages
129
Air con unit starting to make a few odd noises!
What's the current consensus on the most cost effective manner to replace the compressor for an owner in Perth Australia?
I'd made note of
"Sanden sdv16" compatible with Alfa 155.
Replace with parts from Eurospares?
Rebuild locally?
Source the Alfa compatible ?
 

BL330

Member
Messages
1,121
Air con unit starting to make a few odd noises!
What's the current consensus on the most cost effective manner to replace the compressor for an owner in Perth Australia?
I'd made note of
"Sanden sdv16" compatible with Alfa 155.
Replace with parts from Eurospares?
Rebuild locally?
Source the Alfa compatible ?
Hi Migliore, Unfortunately I went through this 18 months ago.
Before we talk compressors we need to establish the exhaust type you have and whether it will get in the road of removing or even seeing the air compressor.
If you have the 2 bolt US spec there should be room to maneouver as the header with inbuilt cat exits more rearwards. This will make fitting much simpler for your mechanic.
If like me you have the 4 bolt Euro spec, then there is also likely to be a heat shield to protect the compressor and starter motor from the heat as the header wraps under the motor. I needed to use a camera scope to read the back of the compressor to determine its type.
Secondly, Maserati used 2 models of compressor, maybe to have supply options in case of a hold up. The Sanden you mentioned and a Delphi model.
Supply - I was pointed to compressor express from Hungary by forum members. The price was great at 521 euro = 50 euro shipping, until we discovered I had the Delphi model which was another 66 euro at the time. They had refurbished stock as well but expert local opinion was rebuilt can't be trusted. The delivery arrived quickly and was as described a brand new compressor. They were way cheaper than Eurospares and other sources.
The work - as the bearing in the compressor had seized, mine broke the auxiliary belt. We took the opportunity to replace the belt and the tensioner and pulley the belt runs over. It took my mechanic 1.5 hours to clear the burnt rubber from the grooves in the crank pulley, so fortunately you've got to this in time. If it is a 4 bolt header, then the task involves lifting the passenger side of the motor to remove the header, to bend / remove the heat shield. Whilst in there they suggested we look at the starter motor as the whole process would be required to get to it at a later date.
So don't drive your car much for fear of the compressor seizing. If you can hoist it at home and view the type and model of compressor, then your on your way.
Regards,
Bruce
 

Migliore

Junior Member
Messages
129
Great information, thanks very much.
It will save me a lot time working it all out.
 

Migliore

Junior Member
Messages
129
I can't get onto the Eurospares site at the moment but earlier I noticed 2 compressor types both around GBP 360, $750 plus delivery.
I've the Euro spec exhaust system so identification will be tricky too, I'll ask my mechanic if he has a camera scope.
 

Swedish Paul

Member
Messages
1,807
Where does the noise come from? I have an odd surging noise coming from the dash, changing temp often makes it go away. I have been told it's common, something to do with pipes and such. Doesn't do it with the aircon off and just blowing.
 

mjheathcote

Centenary Club
Messages
9,033
Where does the noise come from? I have an odd surging noise coming from the dash, changing temp often makes it go away. I have been told it's common, something to do with pipes and such. Doesn't do it with the aircon off and just blowing.

Low on refrigerant.
Mine was exactly the same from the day I bought her, and thought they all do that.
Then I did a favor for a garage next door at work, and in return just asked if he could check the a/c, for I just thought it was not quite as cold as it could be.
The result was that it had something like 2/3rd the refrigerant it should have.
Now silent, and super cold!
 

Swedish Paul

Member
Messages
1,807
How much refrigerant? The book says 750g, but mine was overfilled the first time I recharged last summer to 1000g and the noise went away. Reduced back to 750g and the noise came back (sometimes). Was told overfilling can cause failure by someone on the forum here last summer.
 

adam01

Member
Messages
1,079
How much refrigerant? The book says 750g, but mine was overfilled the first time I recharged last summer to 1000g and the noise went away. Reduced back to 750g and the noise came back (sometimes). Was told overfilling can cause failure by someone on the forum here last summer.

Actually there are two values depending on country.

Without looking up,
Euro is 750
US 1024 from memory

Not sure how you determine which unit is what
 

Zep

Moderator
Messages
9,110
How much refrigerant? The book says 750g, but mine was overfilled the first time I recharged last summer to 1000g and the noise went away. Reduced back to 750g and the noise came back (sometimes). Was told overfilling can cause failure by someone on the forum here last summer.

That would be me... The problem is there are no pressure relief valves in a car A/C system, so overfilling can result in rupture of a pipe if the pressure climbs too high. The system is designed to hold a certain amount of refrigerant in liquid form and a certain amount in vapour form, if there is too much in total when the temperature rises the amount of liquid reduces and the overall pressure goes up, if it goes too high something goes bang, and I can assure you the energy released in a pipe rupture at 10 bar is significant and damaging. Additionally, if there is too much refrigerant liquid refrigerant makes it back to the compressor and washes out the oil, causing seizure.

It is the transition from vapour to liquid and vice versa which provides the cooling. The noise you hear is the sound of liquid refrigerant evaporating inside the evaporator. If the system is slightly short of gas, the entering air is particularly warm or the expansion valve is sticking you will get some noise. If it is minor and occasional its not much to worry about. If it is very loud and regular then it is either short of gas (as Mike rightly pointed out) or the expansion valve is sticking or cannot adjust.

Things to check are:

Running pressures and temperatures - Your A/C tech should be able to attach gauges and measure things like head pressure and suction pressure and calculate superheat and sub cooling. If they can't, find one who can. Guesswork doesn't work with these things.
Check for moisture - Was the drier changed? If there is too much moisture in the system it can form ice inside the expansion valve which makes it stick or reduces the size of the orifice with the same effect. If the system has been left open to atmosphere in the past the drier can be saturated leaving free water in the system.

Once these things have been checked, trim charging with up to 5% of the rating plate amount of gas is unlikely to cause problems, but if it takes 25% to stop the noise, you probably have a faulty component.
 

CatmanV2

Member
Messages
48,557
Low on refrigerant.
Mine was exactly the same from the day I bought her, and thought they all do that.
Then I did a favor for a garage next door at work, and in return just asked if he could check the a/c, for I just thought it was not quite as cold as it could be.
The result was that it had something like 2/3rd the refrigerant it should have.
Now silent, and super cold!

Interesting. I'll get mine looked at. It's plenty cold enough but does sound like there's a small washing machine churning away behind the dash :)

C
 

mjheathcote

Centenary Club
Messages
9,033
That would be me... The problem is there are no pressure relief valves in a car A/C system, so overfilling can result in rupture of a pipe if the pressure climbs too high. The system is designed to hold a certain amount of refrigerant in liquid form and a certain amount in vapour form, if there is too much in total when the temperature rises the amount of liquid reduces and the overall pressure goes up, if it goes too high something goes bang, and I can assure you the energy released in a pipe rupture at 10 bar is significant and damaging. Additionally, if there is too much refrigerant liquid refrigerant makes it back to the compressor and washes out the oil, causing seizure.

It is the transition from vapour to liquid and vice versa which provides the cooling. The noise you hear is the sound of liquid refrigerant evaporating inside the evaporator. If the system is slightly short of gas, the entering air is particularly warm or the expansion valve is sticking you will get some noise. If it is minor and occasional its not much to worry about. If it is very loud and regular then it is either short of gas (as Mike rightly pointed out) or the expansion valve is sticking or cannot adjust.

Things to check are:

Running pressures and temperatures - Your A/C tech should be able to attach gauges and measure things like head pressure and suction pressure and calculate superheat and sub cooling. If they can't, find one who can. Guesswork doesn't work with these things.
Check for moisture - Was the drier changed? If there is too much moisture in the system it can form ice inside the expansion valve which makes it stick or reduces the size of the orifice with the same effect. If the system has been left open to atmosphere in the past the drier can be saturated leaving free water in the system.

Once these things have been checked, trim charging with up to 5% of the rating plate amount of gas is unlikely to cause problems, but if it takes 25% to stop the noise, you probably have a faulty component.

It sounds(!) to me like visiting a true A/C specialist should be able to sort things out.
Too many garages although having a machine, are not true specialists in the field.
 

CatmanV2

Member
Messages
48,557
It sounds(!) to me like visiting a true A/C specialist should be able to sort things out.
Too many garages although having a machine, are not true specialists in the field.[/QUOTE

Although I tease him mercilessly, Zep is an expert in his filed as far as I can tell. And I sure as **** trust him! He even managed to not blow up my fancy heating system :)

Zep, we need to sort my oil sensor, mate!

C
 

Zep

Moderator
Messages
9,110
It sounds(!) to me like visiting a true A/C specialist should be able to sort things out.
Too many garages although having a machine, are not true specialists in the field.[/QUOTE

Although I tease him mercilessly, Zep is an expert in his filed as far as I can tell. And I sure as **** trust him! He even managed to not blow up my fancy heating system :)

Zep, we need to sort my oil sensor, mate!

C

You got that working then? Did you need any extra fuses?

Seeing as you have been so complimentary, if you ask me nicely I'll bring a bottle of R134a when we do your oil sender I'm ready when you are...
 

Zep

Moderator
Messages
9,110
It sounds(!) to me like visiting a true A/C specialist should be able to sort things out.
Too many garages although having a machine, are not true specialists in the field.

Never a truer word said. I once took one of my cars to a well regarded a/c specialist in my locality. I explained that I knew what I was talking about and what I wanted them to do. They promptly ignored me chucked some gas in it and weirdly it leaked again. I do it myself now, believe it or not the cost of the refrigerant is £3.50...
 

CatmanV2

Member
Messages
48,557
You got that working then? Did you need any extra fuses?

Seeing as you have been so complimentary, if you ask me nicely I'll bring a bottle of R134a when we do your oil sender I'm ready when you are...


Did you not get my email? No fuses required. :) Have you a preferred weekend? I shall wait for Mrs M to be at football I suspect and come up one Saturday.

C
 

RossWA

Junior Member
Messages
139
I took mine to AutoCool in East Perth and they replaced it with a Sanden unit, cost me $1700, they did a great job and it works perfectly.