Why is it not highly advised for you to perform the A/C system service yourself? What can possibly go wrong?
The system service requires specialist tools and equipment. Other than this, the refrigerant from the system should be recovered and handled safely. You can't just vent the refrigerant and dispose this into the environment. It would be illegal. That's why the service is more complicated than expected. There are certain rules to follow. Also, the system is under high pressure. The pressure should then be pulled down to a near total vacuum in order to get rid of moisture. Since the refrigerant has a low boiling point, it will be dangerous to handle it as this can cause freeze burns. It shouldn't be in contact with the skin, especially the eyes.
Why do some people have the gas of their vehicle's A/C system analyzed? Is this an unnecessary service or expense?
The gas in the system is analyzed by a professional to determine whether or not the air-conditioning system of the vehicle is using the right type of refrigerant. If an incorrect type of gas or refrigerant is used, then this will adversely affect the system. This can cause compressor failure since the gas can't provide the needed lubrication around the system. This will also help figure out if the gas is contaminated or not. If it's contaminated, then most probably, there's leak in the system that should be traced. The presence of moisture and air in the system should be checked as well. This would require cleaning and service.
For the tire pressure, some would use the air pressure information stamped on the sidewall of the tires as reference. Why do some people say that this isn't the right measurement for inflation?
The tires of your vehicle should be inflated according to the manufacturer's recommended air pressure. The owner's manual can be used as reference for this. The recommended tire pressure can also be written on the door post or found on the glove box door. The air pressure limits on the tire's sidewall isn't the one you should follow since this is the maximum tire pressure. If the vehicle isn't loaded to its max carrying capacity, then this will lead to a rough or hard ride. You may also notice some changes when it comes steering control.
Can I tell through a bounce test if the shocks of my Ford EXP are already worn out? Is this reliable? How should this be done?
The bounce test is done to determine whether or not the vehicle bounces excessively, which is one of the symptoms of having bad shocks. On the corner of the vehicle, right above the wheel, push down on the vehicle body about 3 to 4 times to bounce the vehicle. If the vehicle stops bouncing after a rise and fall, then the vehicle's shocks are most likely still in good condition, but if the vehicle bounces excessively or repeatedly, then you'll have to check these suspension components for wear. If there are leaks, then the seals are already broken and these may require replacement.