Blog Car Parts

What is a wheel hub bearing? Why do I care? A wheel hub bearing is the ONLY part connecting the body of the car to the wheels. It is apparent in the definition what makes the wheel hub a part of great importance.   IT IS THE ONLY THING CONNECTING YOUR CAR TO THE WHEELS! Suprisingly, it is often overlooked because the symptoms of a worn wheel bearing are similar to those of worn brakes, rotors, pads, etc. The result is an over diagnosis of brake / strut issues and the under diagnosis of the wheel hub bearing.

The average American spends over a quarter million dollars on his/her car(s) in a lifetime. A major chunk of this amount goes to car repair and maintenance costs. The current generation’s mentality towards car repair and maintenance is “will take care of it as it happens.” The passive mentality results in very little mechanical knowledge about the important parts which run the car. The wheel hub bearing is one of the most overlooked car parts, especially for the average car user.

The current trend in car parts is moving towards a complete wheel hub assembly design. The traditional wheel hub is a simple bearing where the body of the car attaches to the wheel of the car. The newer design which gained popularity in the current decade is a complete assembly of the wheel hub. It includes the wheel hub itself, the bearing, the lugs, and the ABS braking sensor. This is an all-in-one unit which is more efficient in performace and a breeze to replace without the need of a mechanic.

It is equally important to understand the symptoms of a worn wheel hub assembly. First and foremost is the noise coming directly from the wheel hub. If a single bearing is off, the whole wheel hub assembly needs to be replaced. And when a single bearing is off, you can hear the whining noise. If the noise is not caught, there will also be a slipping or catching in the wheel. This is a classic sign of a damaged wheel hub. Some of the newer cars have sensors to monitor the slipping and noise and will send an error code to the computer. A general rule of thumb, if your car has around 90,000 miles, it is time to check the wheel hub bearing.

As a consumer, it is imperative to know the above information for a few reasons. One, you can diagnose your own wheel hub issue without spending time and money with the mechanic. Unless you have a trusted mechanic, self diagnosis closes the door on additional, unnecessary, and fictitious repairs vouched for by the mechanic. This also gives you the ability to negotiate labor hours knowing how easy the job is. Moreover, you can evev do the job yourself now that you know how easy it is.

A final review of the auto ac parts covered – Air Conditioning Expansion Device, Air Conditioning Receiver Drier, AC compressor, AC evaporator, AC Condenser.

-The AC Compressor – superheats and pumps the refrigerant throughout the AC system.  This superheated gas is sent to the condenser.

-The AC Condenser -  cools like the superheated gas and turns it into a liquid.  The refrigerant is now sent to the orifice tube.

-The AC Orifice Tube -  reduces the refrigerant’s pressure and supercools the liquid before sending it to the evaporator.

-The AC evaporator – transfers the heat from the cabin into the refrigerant and turning to back into gas.  The cycle is complete.

Thus far we have covered the following auto ac parts :

1. Air Conditioning Compressor

2. Air Conditioning Condenser

3. Air Conditioning Expansion Device

If you are just now jumping into the conversation, I strongly recommend reading Parts 1-4.  The topic of discussion today is the air conditioning evaporator.  The ac evaporator is the first part to interact directly with the car cabin. It acts as the cabin heat exchanger.  The evaporator aids the cabin air in transfering heat into the refrigerant.  Ultimately, the evaporator also provides another change of state in the refrigerant, this time from liquid to gas.

When the supercooled refrigerant passes through the evaporator, the blower motor forces the passenger cabin air across the refrigerant coils and transfers the heat into the refrigerant. This superheats the liquid to a boiling point and turns the refrigerant from a liquid back into a gas.

Air Conditioning Evaporator

We have breezed through the air conditioning process via the AC compressor and onto the AC condenser. At this point in the process, the AC Orifice tube comes into play. Every air conditioning system has an orifice tube. Some have different names but their job is the same – to serve as a pressure drop device.

The orifice tube’s job is simple. It handles the highly pressurized refrigerant. Specifically, the orifice tube is responsible for reducing the refrigerant pressure. This goes hand in hand with the orifice tube’s ability to cool the refrigerant. The condenser cools the refrigerant by allowing the outside air to remove the heat. The orifice tube further cools the refrigerant down to approximately 32 degrees fahrenheit.

The drop of the temperature is the intended side effect of the drop in pressure initialized by the orifice tube. This “supercooling” of the refrigerant is needed so it can be prepared for maxumim heat absorption in the passenger department.

The pressure drop orifice tube is key because it is hard to keep the temperature at the perfect “sweet spot”. You want the temperature just high enough to prevent any moisture from freezing onto internal parts of the evaporator (more on this part later).

Now that we have an idea of the role an AC compressor plays, let’s have a look at the AC condenser.  If you have ever seeing an air conditioning condenser you might have mistaken it for your car’s radiator. This is common and not surprising at at all considering the job of an Air Conditioner condenser is same as the car radiator.

The AC Condenser’s sole job is to remove the heat from the super heated refrigerant, similar to how the radiator removes the heat from the engine coolant. The AC Condenser has intricate bends and folds which pull heat out of the refrigerant as it passes through. The peculiar turns the refrigerant takes through the nooks and crannies of the ac condenser combined with outside air removes heat from the refrigerant.

The removal of heat results in a change of state in the refrigerant. When the refrigerant initially entered the ac condenser, it was a super compressed and super heated gas. When the refrigerant leaves the AC condenser, it has been cooled down enough to change states from gas to liquid upon exiting.

Air Conditioning Condenser

The auto air conditioning system is, in layman’s terms, a refrigerator with a heavily modified set up for a car. The AC Compressor is an integral part of this layout. The AC compressor’s job is to compress and circulate the ac refrigerant throughout the system; think of it as literally, the heart of the system.

There are many AC compressors out there, in my experience the Sanden AC Compressor, Denso AC Compressor, Delphi AC Compressor and AC Delco AC compressor products are ahead of the pack. These encompass max RPM up to 9000, up to 7 pistons and (Denso especially) some of the quieter, vibration free AC compressors out there.

All these ac compressor performance numbers really mean is how efficiently and quietly a compressor pumps the refrigerant through the ac system. The AC compressor does this by first putting the refrigerant under pressure before sending it to the condenser.

Hybrid principals of chemistry and physics dictate the compression of a gas makes it extremely hot. The AC compressor’s other duty is to super heat the refrigerant. You need this because for an AC system to work, the gas needs to act as a high pressure gas source which will be used later.

What happens to this super heated gas once it leaves the AC compressor? I will cover that in Part 3 as it requires the introduction of another part – the condenser.

In general, a “neighborhood” mechanic understands how the car engine works and by extension, the role a radiator, a water pump, or an oxygen sensor. What I am noticing is a car’s ac system is not general car knowledge. So here is part one of a series on car air conditioning.

This time around, I will keep it simple and answer the following question – what is auto ac?

Auto air conditioning is a combination of the following 7 components. I will go over each one in greater detail in subsequent posts.

1. AC Compressor

2. AC Condenser

3. Orifice Tube

4. AC Evaporator

5. AC Receiver / Drier

6. AC Lines & Hoses

7. AC Blower Motor

So this is a tough one. I had someone who had a computer code claiming the Mass Air Flow Meter was not working properly. The question was can it be repaired or does it have to be replaced. The answer is yes it can be repaired, but probably not by you.

The mass air flow meter detects the amount and type of air coming into the engine. In conjuction with other sensors it determines the correct amount of fuel to send to the engine. By constantly detecting this ratio and adjusting to it, the car can increase horsepower and mpg.

Because it does so much work and is all electronic sensors, you would need some pretty spiffy machines to repair it. There are a few companies who do the repair, so I think you are better off buying one and doing the install yourself. Typically a pretty straight forward install depending on where it is located.

What is a reverse rotation steering box and when is it used?

A Reverse rotation steering gearbox is when the output shaft turns at the opposite direction to the input shaft. This is done by changing both shafts inside of the box. The input shaft for reverse rotation would need to be connected on the opposite side of the output shaft. This will enable the shaft to turn in the opposite direction.

Reverse Rotation Gearbox is used on most Chevrolet Van Steering Box and on some Dodge Van Steering Box. Most cars put the steering gear behind the front axle. This is considered standard. These vans have very forward chassis designs and thus the steering is ahead of the front axle and unless you want the van to steer opossite, you will need the box to be reverse.

The other reason for reversing boxes is hot rod or specialty applications that are pushing the steering ahead of the axle. Many of these people will have gearboxes changed. Some gears can and some cannot be converted. The Dodge Ram Steering Rack cannot be changed, but many other applications can be changed over.

For the sake of your internal car parts, keep an eye on the coolant. Whether you own a Toyota, Chevy, or Audi – you will have to do regular maintenance. You would be surprise how uncommon the ability to change the coolant is. Here goes:

Its should be pretty common knowledge, but you should always keep the coolant level full. Engine coolant helps keep the temperature of the engine in normal range. Low coolant level cause the engine overheating, which is vital for the engine. Also true is that it keeps the engine from freezing.

How to check the engine coolant fluid level:

The coolant level should be between “LOW” and “FULL” marks in the coolant expansion tank as in the picture. If it’s lower, you should top it up. If there is no coolant in the expansion tank at all, you should add the coolant into the radiator also. But remember, NEVER open the radiator or the expansion tank cap when engine is hot! It can burn you and cause serious damage.

Changing engine Coolant:

When engine temperature is close to normal, which is usually at least 10 minutes after the engine is off , simply add coolant into the expansion to “FULL” mark. and into the radiator if needed.

Adding engine coolant:

Remember, you should also flush the system every 60-90K miles. This ensure that no build up or contamination gets in there. This should be done more frequently if you are driving off road, in high temps, or high mileage.