With temperatures continuing to rise across the world & summers becoming more & more unbearable with each passing year, there’s no better time than now to take a look at the evolution of cooling through the years & how man grew to be dependent on his little invention.
Did you know that man’s attempts to keep his homes cooler than the outside temperature have been going on since ancient times? However, it was only in 1902 that Willis Havilland Carrier invented the first modern air conditioner.
There are a few historical moments to note which influenced the development of automotive air conditioning (MAC) -
- 1987 Montreal Protocol phased out of ozone depleting substances
- 1994 R12 refrigerant banned in all automotive AC & replaced with R134a
- 1997 Kyoto Protocol signed to protect earth’s climate reducing green house gases
- 2013 R134a green house gases compulsory replacement with R1234yf in all new car models
If you are interested in knowing more such interesting facts about the progression of air conditioning through the years & how it changed the world in more ways than one, don’t forget to take a look at the stunning, new infographic from Sovereign!
(Content reproduced with permission from Sovereign Planned Services Ltd, UK)
A Mobile Air Conditioning System (MAC) cools the interior of a car’s hot cabin in a very efficient way as compared to a home air conditioning system. If your car is parked under the hot sun, the cabin temperature can be expected to hit a high 50C. And when you drive off from this situation, the car’s ac must cool the cabin in a matter of minutes.
Recently, a customer request me to review the performance of his Mazda CX5 AC after a total compressor oil change. Here are the results. The test was done with a starting AC vent temperature of 19C & the front 2 windows are left opened. The AC was then started under different settings & the AC vent temperature is measured. A good car AC system should have its AC vent temperature below 8C & resulting cabin temperature would be able to reach 23 C or better.
1. Is my AC contaminated with other refrigerant ?
2. Is my AC cold enough ? Is it below 8 C ?
3. Is my AC compressor oil in good condition ?
4. Is my compressor performing well ?
5. Do I need to change parts ? Or any alternative solutions
6. Is my AC leaking ? Where & how big is the leak ?
Does it need replacement or can it be repaired ?
If our workshop can identify & solve the above 6 problems, which we face day in day out, we can safely regard ourselves as a quality AC workshop.
Here is a link to our KoolTec AC workshop concept.
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The AC compressor in a car is the heart beat of the air conditioning system. To understand how a car AC system works, please read my other blog here.
An AC compressor pretty much works like a water pump. At the intake side of the water pump, the water is at a lower pressure. The pump’s job is to take in or suck in this low pressure water so it enters into the pump & gets pressurised or pumped up to a high pressure. The output of the water pump would have a high pressure so it is usable to us, like water from our tap or even to feed this water into a garden hose to water your plants.
The AC compressor behaves the same way. It draws in or sucks in the low pressure refrigerant in gas form from the output of the evaporator. The liquid refrigerant that passes through the evaporator is “boiled” to a vapour. This gas form of the refrigerant then makes its way into the AC compressor & gets pressurised to a much higher pressure & temperature.
The the low pressure intake or suction side of the compressor you would expect to see the pressure at 25 PSI & the output of the compressor at a high pressure of 225 PSI. This operating pressures ensures the car AC system works at its optimum parameters giving you a cool ac.
Click here to watch a video on how a AC compressor works.
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This was the Yaris exhibited in 2010, IINAPA Exhibition in Jakarta. It was brand new.
This month I’m delighted to use this car while waiting for my new ride to arrive. The moment I cranked the car, adjusted the seats & the mirrors I noticed something is not doing well.....
First, it took a second too long to crank start the engine, the AC is way too warm & humid in fact it is warm in the day & cold at night, the engine is revving too loud & the auto transmission is not shifting gears smoothly. I’m someone who demands a quality drive so I set about improving it...
The engine performance
Added 1 can of Lambda oil extra & 1 can Tank Otto..that makes the engine calms down, the noise is reduced significantly 7 improve power! Installed 2 Qmax nano to maintain the engine power performance.
The Air Con
Flushed the air con with “KoolTec”. Before the compressor oil change the temp is 17C & after flushed its 4.5C. Now the AC is cold in the day! And fogged the AC for 30mins, I can enjoy fresh air free of bacteria.
Battery test yielded a (-100%) results. A brand new battery is 100% life & overtime it will degrade & when its at 30% it must be replaced. This battery (45Ah type) is minus -100%, it must be replace immediately.
Upon replaced, started the car & it stalled again, switch on AC compressor toggle on & off..thats funny. Pulled out my AutoTest electrical analyzer & measured - charging voltage only 12.7V (normal at least 13,8V) & the charging current is -20A!!! Shut off the engine, pulled out the fuse for the ECU for a few seconds & plug it back again. Problem solved - charging voltage at 14.5V & charing current at 5A. Lesson learnt - new cars its recommended to plug in a back up battery before replacing batteries. Look out for my future Tech Talk series about the back up battery part.
With a new battery & without fail each time you installed a 100% life new battery into your car, you will notice & feel that the car is more powerful, the head lights is brighter, auto transmission shifts smoothly & the car audio sounds better. These improvements are only momentarily. And there are ways to maintain & improve the electrical performance in your car. I will talk about them more in my next Tech Talk Series.
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Enjoy your car.
Hybrid vehicles ultilize 2 sources of energy to power the car, fossil fuel either gasoline or diesel & batteries.
A Honda CR Z Hybrid pulled into his garage & the owner complained of very hot AC. The standard diagnostics were done & the temperature measured was 20 degrees C. Since 90% of all AC failures are caused by the compressor lube/oil not replaced, my customer went ahead to flush out completely the old compressor oil. To our surprise the amount of oil is too little.
It was a good thing WW called me & enquired on the factory specification on the amount of PAG oil is needed for this CR Z.
Hybrid cars, like the CR Z, uses electrical compressors compared to belt driven ones in conventional cars. The compressor oil, THIS IS VERY IMPORTANT TO NOTE, you must use a special compressor oil called “Hybrid compressor oil” of viscosity 100. Why? Hybrid compressor oil do not conduct electricity! After added the new hybrid oil of the correct amount, the AC was a chilling 1 degree C! Amazingly cold & a very happy customer.
Please never ever use conventional compressor PAG oil in any Hybrid cars. Consult your nearest KoolTec service centres for your hybrid cars AC servicing.
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Go Green & reduce your carbon foot print.
PAG ( Poly-Alckylene-Glycol ) is the chemical name for compressor oil used in R134a car ac system. But all compressor oil made the same?
I’m sure most car owners change their engine oil frequently. Service interval usually for semi-syn oil is 5000 km & fully syn at 10,000km. These oil quality & grade varies from brand to brand & what is important is the additive that is blended with the base oil. The quality & quantity of the additive determines the price & quality of the drive.
PAG oil with good quality additives can extend your compressor life & keep your ac cold longer
PAG oil is quite similar in nature. They are fully synthetic, fully soluble with R134a refrigerant & most important there are additives in there to help maintain the operation of the compression & protection of the seals & O rings.
Match car manufacturer’s viscosity specifications
PAG oil comes in different viscosities - 46, 100, 125, 150 & esther to match the specifications required by the car manufacturer. If the amount of oil, viscosity & amount of refrigerant is correctly “mixed’ in the ac system, you’ve get a fantastically cold ac...period.
PAG absorbs water & air easily
PAG oil are hygroscopic, it absorbs water & air readily. The way it is stored & added into the ac system will affect the water & air content in the PAG oil. Oil with excessive water & air can cause damages to the ac components.
Insist on good quality PAG oil the next time you have your compressor oil replaced.
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Modern cars are much more luxury in their fittings now a days. Leather interior trims, leather seats, luxury carpets, bigger dash boards to house all the displays & gadgets & the list goes on.
Have you sometimes wonder? In the good old days when I sat in my father’s red Toyota Corolla in the 1970s, those cars do not come with AC. We simply open the windows & let the wind blow us cool or even with the windows closed on a rainy day it still feel not too hot.
Why can’t we do the same now? Some people may say, its the global warming! Yes that must be one of the attributing factors. Lets have a closer look at the picture above & I think it answers the question “ where does the heat comes from? “
This means we need the car’s AC to perform efficiently & at its optimum if we want to see that heat removed from the cabin.
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You can do your part in anyway, big or small, to save our earth. Go Green.
In the good old days, we frequently see automobiles having to go through overhaul of engine. The lubricant companies began to educate workshops & car owners to replace engine oil at recommended service intervals. Now, we hardly see our car going through the cumbersome engine overhaul piece of work. We diligently replace our engine oil at 5000km or 10,000km.
AWARENESS = ACTION = HEALTHY CAR ENGINE
The primary purpose of lubricants in general are (1) Lubricate to reduce friction (2) Remove frictional heat (3) To absorb dirt. Over time, it would loose its viscosity, its ability to lubricate & it would turn acidic. There are now specific service intervals for engine oil, ATF, manual gear oil, differential axial oil, brake fluid, power steering fluid & radiator coolant.
Replace compressor oil (PAG) every 20,000 km
The service interval for replacement of compressor lubricant is between 20,000 km to 30,000 km depending on the driving condition. The modern car ac system uses PAG( Poly-Alckylene-Glycol ), which is synthetic, compressor oil & refrigerant R134a. The PAG oil mixes 100% with the R134a & it flows through the entire system lubricating the compressor. The amount of PAG oil & R134a a car ac system needs is specified by the car manufacturer & it differs from manufacturers.
PAG oil - correct amount to use
Unlike engine oil, where we use a large amount to lubricate(in the range of 4 liters) , the PAG oil used is usually in the range of 70ml to 200ml. This makes the PAG oil quantity or amount very critical to obtain a cold temperature. Here’s a way to picture this. If your car engine needs 4L of oil, if we add in an extra 2L or drain out 2L of oil. This would adversely affect the performance & protection of the engine & eventually lead to serious damages. Too much PAG oil or too little of it would similarly affect the performance of the compressor & its lifespan.
PAG oil replacement - A pain in the ass!
Traditionally, it is a very difficult & time consuming task to remove the compressor oil. The compressor, condenser, evaporator & expansion valve must be removed & flushed separately. And the dash board must be removed to get to the evaporator & expansion valve. Now there is a “Cool & Simple Way to Make your car AC Cold” - KoolTec . The AC compressor oil can be removed & replaced with new oil in just 1 hour & no parts are removed in the process. Check out your nearest KoolTec service centres for a free diagnostic check.
Replace your car’s ac compressor oil every 20,000 km to enjoy a cool & fresh cabin & avoid expensive repair cost!
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A comfortable air conditioned environment for us is between 20 to 29 degrees C & a humidity range of 30% to 70%. For example, for the car’s cabin temperature to reach 20 C the humidity should be at 30%. To efficiently achieve this level of coldness, the temperature measured just on the surface of the evaporator or cooling coil would be about 2 C.
A quick way to access your car’s ac performance is to wind down both the driver’s & passenger’s side window & set the ac to the coldest mark. You would then measure the temperature in the ac vent. A minimum performance standard, the ac vent temperature would be about 8 C or lower, the lower the better. We have a video to demonstrate this performance measurement.
In my next Tech Talk Series, I would discuss further how we can achieve the optimum performance out of our car’s AC without removing parts in the process & we will discuss the contributing factors that causes our car’s AC to lose its efficiency.
Keep cool & stay heathy.
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Watch the video here
Laws of physics
- Heat travels from a hotter place to a cooler spot
- Change of state - (a) when water is heated up it absorbs the heat energy & evaporates or boil (gain heat)
- (c) if you place a cool piece of glass over the steam , it condenses into water droplets. (lose heat). The water changes state again, from gas to liquid
An AC system uses these principles to cool the car’s cabin. The objective of the ac is to move the hot air inside the car to the outside of the car. If we can move this hot air mass quickly enough & efficiently, we get nice cold air in the cabin.
Instead of using water, a car’s ac system uses a chemical called refrigerant ( R134a ). It has a funny characteristic, it can change state very quickly from liquid to gas state & vs versa. In liquid form the refrigerant is cold & when it absorbs heat, it can quickly evaporate or boil & become a gas. When in gas form & if it is cooled, the gas refrigerant would quickly become a liquid again.
Here’s how it really works. There is a component called an evaporator or cooling coil mounted inside the dashboard. The evaporator has liquid refrigerant flowing through it & its very cold ( on the surface about 2 degree C ). An electrical blower or fan is used to draw the hot air in the cabin onto the evaporator. The heat is absorbed by the cold refrigerant & what comes out from the evaporator is cold air.
The heat converts the liquid refrigerant into gas & it is moved by the compressor towards another component called a condenser. Cooler air from outside the car is drawn in by the forward movement of the car & the engine cooling fan. The condenser is usually at a temp. of 60 degree C. When the cool air from outside the car flows through the condenser, it cools the refrigerant, which is in gaseous state inside the condenser & it changes state to liquid again. This time the compressor will push this liquid refrigerant back into the evaporator & the cycle goes on over & over again in a split second.
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Q What are the related automotive systems the AC in your car depend on to function properly?
For a car’s AC system to operate efficiently, 3 systems must function well. The engine power train, the engine cooling system & the electrical charging alternator & battery.
The engine power train drives the AC compressor through a pulley belt, which directly drives the piston in the compressor. If the engine compression is unbalanced or its vibrating violently due to wear, there may not be enough torque to drive the compressor & leads to a poor performing compressor.
The battery provides enough crank current to start your car engine & the alternator takes over from that point to supply the electrical demands of your car including charging up the car’s battery. When the battery reaches its service life time it can cause havoc to the alternator. The charging voltage can fluctuate & the charging current drops. If the supply voltage drops below 12V it can cause the compressor clutch to burn off!
The engine cooling system comprises of the radiator, radiator coolant, water pump, engine cooling fan & the radiator cap. These components work in close harmony to keep the engine cool & at its optimum operating temperature. If the engine overheats, usually during a long & high speed drive, the AC compressor can heat up too causing an increase in refrigerant pressure resulting in hotter AC.
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Myth #1 - It’s a closed loop system, therefore needs no maintenance
Air con compressor oil is subjected to great heat & stress, second only to engine oil. Overtime, oil breaks down & becomes acidic, causing wear, corrosion, reduced cooling efficiency & increased fuel consumption. The compressor works harder, failing prematurely & requires costly repairs.
Myth #2 - Changing air con cabin filters regularly is sufficient to ensure clean air from your car’s AC
Unless your car is a top-end car using HEPA ( High efficiency Particulate ) air con filter, this is totally untrue. Bacteria & other harmful microbes thrive in dark & moist areas such as your air con evaporator. Our high humidity ensures that the evaporator remain wet for hours after the engine is switched off. In just a few months, any new car’s air con will be filled with mould & bacteria, which conventional air con filters are unable to remove. HEPA filters also reduce airflow drastically & thus are not suitable for normal cars.
Myth #3 - Wait a minute, I use a cluster ioniser in my car, I should be ok!
Ionizers cause dust & other particles to form clumps, which tend to settle more quickly. This means that you do breathe in fewer impurities, but those that you do not breathe in are likely to be in larger lumps. Sounds worse, doesn’t it?
Myth #4 - Air Con maintenance actually causes AC failure
If you have an old car & never performed air con maintenance, your air con evaporator can be corroded & your compressor may fail or jam soon. In this case, servicing the air con could lead to failure. However, with newer air con compressors, which are still working fairly well, regular change of air con compressor oil ( every 20,000km ) prolongs your air con compressor’s lifespan.
How many times do you have your home’s air conditioning serviced & maintained? Perhaps 2-3 times a year? The service job includes refrigerant top up, filter & blower cleaning to ensure you have a clean & cool air. The question is, how many times do you have car’s AC system serviced in a year?