We tend not to think about parts like an oxygen sensor until our check engine light comes on, and really why would we? If we knew a bit more about the importance of an O2 sensor when it comes to the performance of our vehicle we may feel differently. Sometimes referred to as an air fuel ratio sensor, oxygen sensors play an important role in fine-tuning an optimum air fuel ratio. At any given moment your oxygen sensors will determine whether or not your air fuel ratio is lean or rich. A faulty oxygen sensor can translate into lower than normal MPG… a side-effect any of us can ill afford. Allowing an old O2 sensor’s signal to continue to slow will result in decreased acceleration and overall performance. Vehicle emission control is another area where oxygen sensors play a crucial role.
You can find many original equipment as well as aftermarket options when searching for an O2 sensor for your vehicle. Remember that your vehicle may have several different oxygen sensors. Common names for these sensors include pre-cat, post-cat, bank1 sensor1 among others. Before speaking with your oxygen sensor vendor, be sure you’ve done your homework so you’ll know exactly which sensor you need.
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.
Someone asked me what is the best way to find a good mechanic. I said I recommend going on referrals, but here are a few tips.
Stay away from the dealers and large chains. The person who actually works on your car is a low wage hourly employee in a training program, not a certified mechanic. Avoid the very small places that look sketchy. Find a nice 4-10 bay garage, that is a good size.
Ask friends for referrals, they will be best. You can check online reviews, but there is usually just not enough data. One ‘review’ might be from the shop itself. You need at least 10 reviews to make it legit.
AAA has a good list of mechanics too. You can check with them. AAA requires certain things of their shops including guarantees, so that is a good list to go off of.
