Car Aircon Service

Comptessor equals moving parts equals shoulf be serviced. Gassified system equals efficiency levels equals should be sporducally monitored and regassed when necessary

If it aint broken then don't fix it!
Air conditioners are like your fridge in your house , they are fully sealed and can last up to 20 years without needing any money spent.
Just make sure that you use it regularly/weekly even in winter .
That will keep all the seals oiled as the oil is added to the refrigerant.

I live in Vic...what is this 'aircon' you mention?

Dunko, last time I had my aircon regassed I was given a ppm reading showing there had been a significant loss. Minor repair needed then regas. Thats why I put 'when necessary' in my post. With these things, a loss in efficiency is your first clue a fault might exist, followed by a reading from the gas system to see is something has been lost.

That would be the minor repair I mentioned

Edit:
Ah, you deleted the post dunko, must have reread the post? All good.

Beat me

Hang on, that wasnt a request. Just saying your post came up as I wrote my edit...

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dirtyharry said..
I don't mean to hijack this thread, but does anyone know why my aircon is making a funny sound and leaking water onto the passenger footwell? It tends to make the most noise when I'm slowing or turning right, so I suspect there's water pooling somewhere and getting in/on the fan/fan bearings. I guess it's probably a blocked drain/filter somewhere as it's still cold and working. Does anyone know where I should start looking? It's a Hilux (2010). Thanks!

At least on commodores, they have a drain around the evaporator which condenses water from the air when it cools down the air. The vents went down around the transmission tunnel, but they would block up with gunk and the water would leak into the cabin.

Find the vents and see if they are clear.

Back to the question,..

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ikw777 said..
What's involved in servicing your car aircon? What are you actually paying for? Is servicing your car's aircon really necessary and does it maintain performance and longevity?

The only thing which might need servicing is cleaning the evaporator unit, and that's only necessary if the car has been operating under really dirty or dusty conditions.
The evaporator can get clogged up with dirt in much the same way as dead bugs accumulate over the car radiator.
For air con evaporators in cars, this usually takes many years, ten at least.
The evaporator is usually tucked way up under the dashboard and you have to dismantle half the car to get at it, so when someone 'services' your aircon, they never clean the evaporator. So the only thing which might benefit from a service, usually doesn't get serviced.
Unless the system is not working properly, any other 'servicing' is a rip off. Don't do it.

You can determine if the system needs re-gassing very simply yourself.

Start up the car. Let the motor run for two minutes. Leave the radio off.

Turn on the aircon, set to maximum cold and run for two minutes, with motor raised a bit above idle,.. say 1500 rpm.

Turn off the motor and listen for a hissing gurgling sound under the dashboard, a bit like water running under pressure.
It needs to be quiet to hear this which is why the radio has to be off.
The hissing gurgling sound should last for about 10 seconds. If it does, everything is fine.
If it lasts 2 seconds, you're running low on gas but it's still good for another year or two.
If you don't hear anything, either you're going deaf or the aircon probably needs regassing.

Another indication of the need for a re-gas is if the aircon compressor keeps turning on and off after it's only been running for a few minutes, say five minutes or less.
You can check this by opening the doors, turning on the aircon to maximum cool, raise motor revs to about 1800 rpm, and then opening the bonnet and looking at the aircon clutch pulley, and listen to the compressor sound. The compressor clutch should remain engaged continually if you leave the doors open because you will never cool the whole planet.
If the compressor cycles off and on every few minutes ( you can easily hear this) then it's almost out of gas. Get it re-gassed or you will end up burning out the compressor clutch.

The system has a pressure sensor which de-activates the compressor clutch when the pressure gets low. This is to prevent the system pressure going negative and sucking in air past the compressor shaft seal. They are made to seal against positive pressure, not negative. ( You should never have a negative pressure in the system.)
When the compressor forces all the available gas into the high pressure side of the system (the evaporator), there is no gas left for the compressor to work with so the inlet side to the compressor goes negative. The system is designed so that with sufficient gas, this will never happen.

Don't bypass the negative pressure sensor switch, except for a short test.
It will appear to work fine for a few days but then the system sucks in air. The air contains moisture which condenses and then freezes across the capillary tube, which causes a sudden huge pressure in the compressor and possible damage. Usually, the compressor locks up and the belt screams. In any case, bypassing the pressure switch is not a fix, but you can do it for a few minutes just to check if it stops the compressor cycling on and off due to low gas levels.
Most systems contain between a half kg to one kg of liquid refrigerant, and they will work fine down to about a hundred grams or less.
There is no point in re-gassing it early.

Thanks fellas, sounds like I need to spend some time poking around under the dash and bonnet. I appreciate the help.

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jeff2 said..
If it aint broken then don't fix it!
Air conditioners are like your fridge in your house , they are fully sealed and can last up to 20 years without needing any money spent.
Just make sure that you use it regularly/weekly even in winter .
That will keep all the seals oiled as the oil is added to the refrigerant.

I just had major air conditioning problems. Due to my van being an import the gas was drained. I then had it refilled, but the mechanic stuffed it up by putting in r-134a when my van was previously on r-12. The mechanic didn't flush the system or change the oil. Two months later my compressor seized.

After lots of reading on the subject jeff2 is right.

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oliver said..

jeff2 said..
If it aint broken then don't fix it!
Air conditioners are like your fridge in your house , they are fully sealed and can last up to 20 years without needing any money spent.
Just make sure that you use it regularly/weekly even in winter .
That will keep all the seals oiled as the oil is added to the refrigerant.

I just had major air conditioning problems. Due to my van being an import the gas was drained. I then had it refilled, but the mechanic stuffed it up by putting in r-134a when my van was previously on r-12. The mechanic didn't flush the system or change the oil. Two months later my compressor seized.

After lots of reading on the subject jeff2 is right.

r12 is no longer available and hasn't been for years. It's one of those chlorofluoro carbons that eats hole s in the ozone layer.

When they are replaced with a new gas, the new gas has to be compatible with the original oil, otherwise it doesn't circulate through the system. It just sits in the low points and the compressor eventually seizes up due to a lack of oil.

That's also one of the reasons why you want the system to shut down when the gas runs out.
When the gas runs out the compressor will eventually run out of lubrication, although the damage is usually minimal because when the gas runs out it's not doing any work compressing.
Some scroll compressors will run quite happily for ages with no oil and can be used as air compressors for 4WD's.

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pweedas said..




The only thing which might need servicing is cleaning the evaporator unit, and that's only necessary if the car has been operating under really dirty or dusty conditions.
The evaporator can get clogged up with dirt in much the same way as dead bugs accumulate over the car radiator.
For air con evaporators in cars, this usually takes many years, ten at least.
The evaporator is usually tucked way up under the dashboard and you have to dismantle half the car to get at it, so when someone 'services' your aircon, they never clean the evaporator. So the only thing which might benefit from a service, usually doesn't get serviced.

Many cars have a air filter fitted upstream of the evaporator coil, which is rarely cleaned.
Usually access for this filter is hidden behind the glove box.

One of our company 18 month old Hyundai's recently had no cold air from the vents, but I could hear the fan running.
So I popped out the glove box, unclipped the filter's access cover and found the filter and its upstream ducting was chokka's with built up dust, pollen and bits of jacaranda leaf litter.

cleaned it out and all is good.

took less than 10 minutes - including time taken to read the handbook so I didn't wreck the glove box door when ripping it out.

stephen

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sotired said..

I thought that's why they make other gasses that are compatible with R12 and not ozone eating. I am sure they are available.

I think propane (or butane) was meant to be a decent substitute, but people were concerned that the small amount of gas would pose a fire problem when your car containing 60 litres of petrol runs into something.

The air con mechanic should know an R12 system from an R134a as from my understanding, they use different connectors, making it difficult to fill one system with the other. I thought there was also something about sight-glasses not being used with the newer gas, hence giving you a bit of a reminder its not the right gas. Although this is all coming from a foggy memory.

I reserve the right to be wrong even about stuff I never said!

Yes, that's how I understand it also.

r-12 was commonly used in cars pre 1994. It was dropped because of it's ozone depletion potential and replaced with the less effective gas coolant r-134a. One mechanic told me the real reason it was dropped was that the Chinese were about to supply r-12 at half the cost that the Americans were selling it for. Lobbyists for r-12 forced a change in policy. Not sure the validity of that - but would be interested to find out more.

A suitable replacement to r-12 is hychill, but it's not so common in Australia. I understand it to be a superior gas to r-134a in that it requires less compression, has better cooling properties and is significantly cheaper. For whatever reason it's banned in Queensland (scare campaign). But is perfectly legal elsewhere in Australia, even for home mechanics to DIY. Harmless to the environment. The r-134a vrs hychill is a controversial subject.

Many air-con "experts" won't touch it. The usual excuse is "It's flammable" or it's odorless, I think an additive has been added to address the smell. And as for it being flammable - no sh1t sherlock - so is petrol. Apparently in Germany hychill is now in common use in all cars.

I've had hassles finding someone willing to put hychill into my van.

An error has been made!

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pweedas said..

blah blah blah,.. and then,..

When the compressor forces all the available gas into the high pressure side of the system (the evaporator), there is no gas left for the compressor to work with so the inlet side to the compressor goes negative. The system is designed so that with sufficient gas, this will never happen.

The high pressure side of the system is obviously the condenser,.. that bit in front of the radiator.
By the time it gets to the evaporator, it's in the liquid phase and evaporating back to the gas phase, and at a lower pressure, otherwise it would not be evaporating.
It was a slip of the fingers which the brain didn't pick up on. Sorry,. I blame old age.