Posted by: All About Automotive on April 23, 2013 A vehicle’s air conditioning system does not create cold air. It actually takes the heat and moisture out of the air that is already in your car, leaving behind cooler air. Having a good understanding of how the components work can help to explain the methods of repairs in the air conditioning system. The freon/refrigerant resides in the a/c system. The a/c compressor initiates the high-side of the system where it is compresses the freon/refrigerant into a high-pressure state causing it to liquefy. It travels through the high-pressure lines to the condenser. The condenser which is similar to a small radiator, puts the liquid in contact with fresh air on the outside of the vehicle, which absorbs the heat from the liquid. It then flows into the expansion valve or orifice tube where it is restricted and becomes gaseous into the low-pressure side of the a/c system. Then it flows into the receiver dryer/accumulator that contains a desiccant bag to remove and collect unwanted moisture/water and impurities.

The clean gaseous freon/refrigerant then travels through the tubing into the evaporator(that is usually located in the passenger compartment of the dash). Freon/refrigerant in its gaseous state is now able to absorb heat from the air passing through the evaporator fins, leaving behind the cooler air. Fans blow this cooler dry air into the car’s cabin. The refrigerant travels back to the compressor in the suction hose of the a/c system to get compressed back into the high-pressure gas and begin the process again. The freon/refrigerant also carries dispersed oil that helps to keep the air-conditioning compressor lubricated while operating. Freon/refrigerant staying charged or in a full state is crucial to the proper operation and lubrication of the a/c compressor. R-12 used to be the commonly used freon/refrigerant up to 1993. All vehicles that were produced in 1994 and later were required by the Environmental Protection Agency to be equipped with R-134 freon/refrigerant, which was determined to be better for the environment.

There were also stricter regulations enforced against the leakage and handling of refrigerant/freon and the repairing of a vehicles a/c system. If the freon/refrigerant level gets low, the a/c system can still operate, even though it may loose some of it’s cooling effect, or it can shorten the cycle of operation, and it can cause damage due to the compressor not being properly lubricated while operating. Checking pressures of the a/c system while in operation can give an indication of low freon/refrigerant, but it cannot tell you how low the refrigerant is. how does heating air conditioning workIf the freon/refrigerant level is low, it is due to a leak that has developed in the system.ac units for sell If you’re a/c system is not working properly, it is a good idea to have your trusted repair facility perform some basic checks. fan not running on ac unit

Check the operation of the compressor, it’s clutch and belt, check the high and low pressures of the system while operating, check proper control panel operation, check heater blower fan and engine cooling fan operation, check for restrictions in the system, check for proper air flow through the condenser and evaporator, check for any obvious leaks. Our next article will talk about leaks in an a/c system and how to find them. Steve and Karen Johnston are owners of All About Automotive in Historic Downtown Gresham. Steve and Karen Johnston are owners of All About Automotive, providing auto repair and auto maintenance in Historic Downtown Gresham. Filed Under: Heating & A/C SystemAre the new-car extras, such as paint protection, underbody coating, and loan gap insurance worth it? Hi, i worked in the automoble field for 8 years, I was the CIO of a large 8 location dealer group.   Frankly, i would be leary of doing business with a company that is still pushing paint protectant or undercoating. 

Undercoating is BIG no no as it will actually cause rust.  It traps water between the steel and the undercoating causing corrosion, it plugs up the door and rocker panel drains as well as drain holes in the uni-body frame rails.  The dealers cost for the undercoating is about 250.00 including man hours, it is a huge profit booster and nothing more.  Although Paint Protectant will cause no damage, it does no good.  It is nothing more than an acrylic polymer protectant which can be purchased at an automotive store...cost for the dealer including man hours, 75-100 dollars.  It is nothing more than a profit booster.  Gap insurance is worth it, if you are involved in a collision and your car is a total loss, the insurance company generally pays you the trade value for the car.  Gap insurance will pay the difference between what the insurance pays you and how much you owe on the car.  for instance, if the insurance company pays you 2k dollars and you owe 3k, the gap insurance will pay the difference of 1k. 

However, if you are finanacing 75 percent of the vehicle cost, then gap is not needed.   Here is my best advice, pay for the car and not a single additional item.  Pay no more than 10 percent over cost, ask to see the dealer invoice, add 10 percent and pay that price.  Gap insurance can be purchased through the finance company after the purchase.  So, if the invoice states the car cost the dealer 20k, you offer 22k and not a dime more as that is a fair profit for the dealer.  Puschase no other add ons, none.  If they wont show you the invoice, there are plenty of honest dealers that will.  I would be very careful with this dealer.  Dealers also make money on financing.  for instance, they submit your loan for approval, the bank comes back and approves the loan at 6 percent interest.  The dealer will add 2 or 3 points charging 8-9 percent interest and the dealer gets the money for the points at the time of sale. Ask them how may points they are adding to the bank rate.  I summary, be careful. 

dont fall in love as there are many dealers with the same car.  Offer 10 percent over the dealer invoice and purchase nothing else.  if the dealer gets defensive, fails to show you the invoice, or pulls other sneaky tactics...go to another dealer.   to find the dealer cost for your car as well as many other informative car buying tips.I just bought a used SUV with 115k miles for my son . Should I pay to have the timing belt changed now? If it is the original timing belt, then yes - check your owners manual for the recommended changing frequency, but from a quick web search (not knowing your exact engine model) it looks like 60,000 recommended internal, and typically last 80-100,000 miles to failure if not changed. The most frequent comment (and a red note items on manufacturer's website) is that you probably have a "zero-clearance" engine, an idiotic design that means if the valves are not fully closed when the piston come to the top, it hits the valves and breaks or bends them or punches a hole in the top of the piston.

Talk about planned obsolescence ! In short, if that is the case and your belt breaks or gets so loose it strips the "teth" off it or slips, your valve timing will be off, and could cause catastrophic engine damage that would require a complete engine overhaul or replacement ! Unfortunately, after looking at a video on how to change the belt, they build it so almost all the auxiliary equipment has to be taken off to change the belt - the alternator, water pump, radiator upper hose, power steering pump, air conditioner, etc - so rough cost is $800-1200 ! If you are getting it changed, it is also recommended to replace the water pump while it is off. Hopefully some Montero mechanic will hop on this question and expand on this, but NO engine belt of any type should be trusted to go 115K miles.Is a transmission flush really necessary?How much does it cost to change transmission fluid At a quick lube type place, with unknown brand of fluid - from about $30-60 depending if done as part of a general fluid change package or all by itself.

If transmission fluid filters need replacing too (usually are changed with fluid change on an automatic transmission), more like $75-125 range. At dealer, using OEM parts and fluid, about twice to triple that. Normal auto repair shop about halfway in between those two. One reason for higher price is they will not (if reputable) extract the old fluid through the dipstick tube and put in new - they will remove the pan or maintenance panel (which commonly has to be done fgor filter replacements) and clean the pan at a minimum regardless. This assumes you do not need band or continuously variable shift friction surface replacement or adjustment, which can crank it up from $50-100 for band adjustment to several hundreds more for replacements. Do NOT let some shop convince you to pay for a transmission flush - not only is it unnecessary, but usually uses contaminated fluid from other cars or harmful chemicals (sometimes even tap water or diesel fluid) and can seriously damage your transmission.

If your transmission filters were not doing their job or you smoked your transmission fluid, the proper cure (assuming not bad enough to require transmission overhaul) is to change to new fluid and filters, then replace them again in a short time - typcially 50-250 miles recommended by manufacturers, to let the new fluid pick up the dirt and sludge and transport to the filters for cleaning. IF manual transmission - from about $40-75 for one with drain pan and no filters, to as much as $200 range for one with filters that requires removing side panel to change filter and clean it out. Again, higher end at dealers. My recommendation - ALWAYS require OEM fluids be used for all but engine oil - mixing brands and additives in equipment is just not a good idea, as they can react with each other and cause serious degradation of the lubricating properties, and even cause gel or sludge in the fluid. A transmission, transfer case, differential, etc should be able to run at least several hundred thousand miles without maintenance if you change the fluid as recommended and use only the same OEM fluids in it.