Auto Air Conditioner Repair Explained.

...An auto air conditioner repair is possible with a little knowledge about just how system works.

You will learn exactly how the auto air conditioning repair is carried out.

Auto ac repair

Before discussing the auto air conditioner repair you need to know exactly how an auto air conditioner works. ( I have used the word Freon in the example — due to my age! However — to save the ozone layer the actual gasses in a auto air conditioner repair now vary depending on year of manufacture)

The first thing to understand is that there are two sides to the system.

• High pressure.
• Low pressure.

The best way of remembering this is:-

The high pressure side is thankfully situated on the outside of the passenger area.

The low pressure side— you will be relieved to hear —is on the passenger side ...phew!

OK. So just what connects the two sides?

I'm glad you asked

Its a brilliant little gizmo called a compressor

It does just that - It compresses the "heated" low pressure gas into “pretty hot” high pressure, high temperature gas before sending it on its way.

But where on earth does it go??

You always ask the right questions!

It goes into a radiator like object called a condenser coil -- which fits just in front of your radiator.

The condenser coil cools all that hot gas right down to the outside air temperature. (Now its liquid.) - before sending it on its way again.

• The liquid freon is forced through a kind of narrow sprung valve which opens only because the gas is at high pressure.
• The valve releases the gas into the low pressure side of the system. The efffect of the change of pressure causes the gas to change temperature. The Freon is now a low temperature - low pressure gas - the gas is now colder than when it left the condenser.

• The gas then goes into the evaporator. The evaporator lives with you in the passenger compartment and takes heat out of the air.

A fan forces the air in your car over the evaporator and heat is absorbed into the Freon gas. Basically the air in your car boils the Freon gas - taking a bit of heat out of it!

(If you have ever used a can of compressed air as a blower you will see ice forming on tha nozzle. So, you can see that as the compressed air is being released — the change in pressure reduces the temperature of the gas rapidy.)

So...the air in your cab gets a little colder — the the Freon in the evaporator gets a little hotter

We have a heat exchanger!

Imagine if you pour some spirit on your arm — your arm immediatly feels cool as the spirit uses your body heat as it boils away.

OK, if you go into the engine compartment and hold the low pressure pipe where it exits the firewall — the pipe work feels cold.

Now....Even though the Freon has taken heat out of the air inside your car the Freon inside the tube is taking more heat from your hand to add to the heat on its way to the compressor.—

Taking the heat out of the passenger compartment.—

” Removing all that hot air in your car —

probably caused by you sitting in stand-still traffic for the last two hours! and takes that hot gas right back to that compressor.

The compressor compresses the........well, you get the idea!

Basically the whole process has just taken a bit of heat out of the air in you car!

The heart of the system is the compressor. And in a auto air conditioner repair will be the most expensive item to replace! This compressor is driven from your cars engine by a fan belt driving a circular metal hub - it drives this hub continuously whilst the engine is running.

But you don’t want the AC on all the time do you? - So how does it know when to start and stop?

This bit is brilliant engineering.

OK, the fan belt turns all the time.

For the purpose of illustration, try to imagine a cone with a hole at the narrow end.

• This outer cone is being turned continuously by the fan belt.
• Imagine another cone sitting inside the first cone with a rod at the narrow end. that rod passes through the hole in the outer “fanbelt driven cone.”
• This same rod is connected to the drive shaft of the compressor - but the compressor is not turning at the moment because the cones are not touching each other.
• OK, now imagine there was an electromagnet to pull the inside cone against the outside revolving cone (the one turning all the time whilst the engine is running)
• Now both cones would be turning together — and the compressor would start compressing!

This is actually how a clutch works — Brilliant eh!

What actually happens is, as the car is getting hot inside — A switch activates an electro magnet on the inner cone. Pulling both cones together and therefore driving the compressor.

Hey. We have a working air conditioner.

Sorry if you knew all that already. But to do an auto air conditioner repair, you do need to know the basics.

OK, just what goes wrong and just “how to do” an auto air conditioner repair ?

• The gas leaks out of the system.
• The oil in the compressor leaks with the refrigerant (the oil travel’s around the system with the gas) No oil equals a broken compressor .
• The very worst case which you really do not want to be faced with in a auto air conditioner repair is a leak around the evaporator — this could entail a massive job removing dashboard and wiring loom. Arrrggghhhhhhh!
• Air — and consequently moisture enters a leak and the moisture turns to ice blocking the system This can be pretty hard to diagnose on any auto air conditioner repair!
• The clutch can stick
• The electro magnet can fail
• On the exit from the condenser coil a woven aluminium mesh can get clogged and might need cleaning
• There is a low pressure sensor on the low pressure side of the system — If the pressure drops too low the sensor sends a signal to disconnect the clutch so the compressor stops This is due to a low level of gas — you will need to top up with frion

Right you know the problems — But you need solutions to make a good auto air conditioner repair. Right?

Right!

OK, you need to find any leaks — the very best way of finding the leak is to use a fluorescent dye. You need to pass the dye trough the system. Leave it running for several minutes and then use an ultra violet light to see exactly where the leaks are. One problem here is that if the vehicle is old all the O rings could fail together — If that is the case you have quite a job ahead of you!

The problem is when you try to change the fittings you are bound to break some of the couplers or damage pipes , which then need replacing. In any auto air conditioner repair this is a real pain!

You have fixed your leaks? Great! This next stage is critical. There’s now air in the system. And what’s worse, —you put it there! Now you’re going to need to vacuum the system and remove the air.

Why? Because it contains moisture. That moisture will turn to ice at the first opportunity — which is when you will be feeling the hottest!

Do not skimp on this job — An hour getting that moisture out of the system is time well spent.

OK ,now you have vacuumed the system you need to replace the oil in the compressor ( it does not need much - so don’t overfill)

• While the system is under vacuum pinch the end on the hose you used to do the vacuuming (don’t let any air in!) and put the end of the tube in the oil pot - the vacuum you have made will conveniently draw the oil into the system. Close the end of the tube, you don't want air in the system, Right?

• The next stage is to get a garden hose and allow it to run on the condenser. This keeps it cool whilst you refill the Freon gas.
• Well, I am assuming, as you are reading this article that you are not going to own the pressure gauges a pro will use — no problem!
• Turn the internal air con to the high setting and the fan on to the high setting.
• connect your gas canister to the inlet nipple to the LOW side of the system and start to run the engine. Make sure the air con is switched on.—
• Go to the large exit hose leaving the firewall ( the one that goes to the compressor) and hold it in you hand.
• When it feels real cold stop! You have just the right amount of Freon in the system.

You have just completed your auto a c repair!! Go grab a beer — you deserve it!

Here is a great video on auto air con from Davidsfarm on You Tube... take a look, he's very entertaining.

Basil meets and greets Mrs Richards

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