Old Car Air Conditioning

Old car air conditioning can be difficult to fix. You'll need some patience to get these AC systems working again.

When you crank up the air on a vehicle that's 10 to 15 years old there's only about a 50 percent chance the air is performing as intended.

When you see one of these vehicles driving by with the windows down on a hot day you know they've given up on trying to get the cold air to flow from their old ride.

Quick Links: AC recharge kits, gauges, diagnostic tools and Air conditioning stop leak.

Let's see if we can stop this from happening to you. I know we live in a world of instant gratification and it would be nice if I could tell you exactly what's wrong with your AC system immediately.

However, these mobile cooling units are complex. If you’re looking for a faster answer to your specific old car air conditioning problem try asking a certified mechanic right now.

On this page we'll connect you to individual articles at the bottom aimed at helping you solve your particular problem. However, we dedicate this page to understanding how the entire system achieves the amazing ability to remove heat from the interior cabin.

When you understand how an automotive air conditioning system operates you'll better understand why it isn't working properly. Sidebar: The refrigerator freezer and central air in your home have all the same components as your automobile.

The theory of refrigeration systems is a simple one. The system gathers up the heat and humidity from the interior cabin and vents it outside. With that said, it takes five separate components working in unison to accomplish this task.

how car ac works diagramCar Air Conditioning Diagram

The Old Car Air Conditioning Doesn't Work

When people come to me with an older car and they say their car air conditioner doesn't work, I start thinking to myself, I would be surprised if it did. The reason I feel this way is due to the level of complexity.

As I mentioned, five separate components need to work at 100 percent individually to produce cold air. In addition, there are support components like the condenser fan, interior blower motor, temperature doors and climate control systems that also have to be in top condition at the same time.

If one link in the chain breaks the result is an unhappy driver dealing with an excessive heat buildup in the interior cabin. Now that we're on the same page about how complicated a car air conditioning system is let's try to simplify it with an excellent graphic.

Automotive Air Conditioning System Diagram

complete air conditioning system diagramComplete Car AC System Diagram

One of the first things a mechanic will do when they're dealing with a driver complaint of no cold air is to run the vehicle and crank the air up to maximum. Next they check the temperature in two specific areas.

You can see these locations on the diagram above. The coldest part of the air conditioning system is right before it goes into the evaporator. The hottest part of the system is where it flows into the condenser.

These two extreme points help the mechanic understand what direction diagnosis will take. Note that you shouldn't touch either one of these parts with your hand and that a mechanic will use a Non-contact digital laser infrared thermometer to take accurate temperature readings.

If these two areas are hot and cold respectively this means the air conditioning system has refrigerant in it and it's functioning to some degree.

This is good news and the next step would be to connect a set of manifold gauges to the high and low pressure test ports. This will tell the technician if the system is filled to its proper level and help them diagnose malfunctioning components.

Key Component in Car Air Conditioning Operation

GM air conditioning compressorGM Air Conditioning Compressor

You can't say that one part of the AC system is more important than the other, because if any one goes down it won't make cold air. With that said, it's hard to look at the AC compressor running old car air conditioning systems in the same way as the other important parts.

Not only does the AC compressor need to function electrically it also needs to build pressures mechanically. I'm calling this part out separately, because it can be an issue on older cars with high mileage.

An old car air conditioning compressor works so hard that an original compressor on a vehicle with over 100,000 miles will need careful evaluation.

A unit that's making noise when the clutch is engaged, but makes no noise with the AC off is showing signs of internal damage. Even if it sounds good when engaged the next question becomes is it building the proper amount of pressure.

When this part wears out inside it fails to create the 250 psi to 350 psi needed to achieve proper cooling. We'll talk more about the AC compressor in a separate article.

DIY Air Conditioning Repair on Old Cars

When you get your AC fixed at an auto repair shop the cost can be extremely high depending on what parts have failed. Sometimes shops try to lure you in with a cheap car air conditioning service.

But when we talk about old car air conditioning repairs the total estimate might even exceed the current book value of the automobile. This is why you see so many people driving with the windows down on hot and humid day.

Unfortunately, the ability for you to repair the system yourself depends on a two factors. Your personal skill level and what's wrong with the system. Mechanics buy special tools and wear safety glasses when they work on these dangerous systems.

Refrigerant is nasty stuff and can do bad things to the human body. Purchasing specialized equipment just to work on car AC systems can be hard to justify for the average driveway mechanic.

However, the price of the AC tools and the needed parts to repair a system could come in way below an estimate from a repair shop. In the end you'll have to decide what's right for you.

With that said, knowing how old car air conditioning systems work and learning about the individual problems from the articles below will certainly help you negotiate with the people fixing your old car air conditioning.

Articles for Fixing Air Conditioning on Old Cars

When the mechanic tells you what's wrong with your automotive HVAC system you may wonder how bad it is. We came up with The Top 3 Worst Car AC Problems that you can have on an older car.

You turn on the AC and you don't hear a click and the air never gets cool. Now it's time to see if the compressor kicks on. Review these 5 reasons the car AC compressor clutch won't engage.

You heard the worst case scenario now here the best one. What if the only thing wrong with your car air conditioner was a $15 part. See how to quickly test the car AC relay for defects.

Chevrolet and GMC trucks have their fair share of inherent heating and AC problems. See one of the unreliable air conditioning control panels to grace the interior cabin of a GM car or truck.

This next article dives deep into one little plastic part that costs around five bucks. My automotive teacher said, this is the part that makes the cold happen. Learn about the problems you can have with the automotive AC orifice tube and how to diagnose them.

Some cars don't have an orifice tube. They have a metering device controlled by a temperature sensor mounted near the evaporator. See how to diagnose and replace automotive expansion valves.

If you have blower motor problems on a Chevrolet or GMC truck or sport utility vehicle we have the solution. Find out about the updated replacement parts kit available for the AC blower control module.

Some popular Ford models also have blower motor problems. In fact, one of these cars needs three separate components to restore reliable operation of the interior fan motor. See why on the Ford Fusion blower motor repair page.

Speaking of Ford blower motor speed control issues, the trucks like the F150 and Ford Escape have their own set of problems and solutions. See why the blower motor resistor assembly has high failure rates on Ford Trucks and SUV's.

Guess What? Even Toyota car and trucks can have problems with the interior fan motor electrical system. Learn about the Toyota Tacoma blower motor problem and why replace the resistor and the connector won't fix the root cause of the issue.

If you're having problems with a Chrysler air conditioning system leaking Freon, I hope it doesn't need an evaporator. See why replacing the evaporator on a Dodge is the pits.

Time to pick on Chevrolet again. Drivers of the Chevy Cobalt complain about a clicking noise coming from behind the glove box. On these cars the failure points to a defective fresh air door actuator motor. See how to replace the part without removing the dashboard.

Speaking of the evaporator, that's where they put the pollen filter on automobiles. See instructions and guidelines for replacing the cabin filter on older Nissan cars.

Sticking with GM air conditioning problems, what's the main cause of air flow malfunctions? The junk blend door motors that came on 10 years worth of vehicles. These same defective GM actuator motors run the temperature door.

The most common reason the AC stops working is because the refrigerant leaked out. See how to find these leaks and see if a car air conditioning stop leak product is right for your issue.

Older cars enjoy a reputation of having bad AC systems that require expensive repairs. See two major innovations in the automotive AC world. Then buy a vehicle that utilizes these technologies.

Visit the FixMyOldRide.com Homepage.

Automotive AC DiagramSimplified Automotive AC Diagram

Author bio : Mark is a retired ASE certified master technician, Chevrolet Professional Service Council member and the founder of FixMyOldRide.com. Watch the video on the about Mark the mechanic page to see his credentials. Mark hand writes all of the articles on FixMyOldRide.com unless indicated otherwise.