Automotive Maintenance

Order Reprints
Tim Craig

For the first time in months, many consumers will turn on the A/C in their car and find the air is not as cool as it should be. Their first reaction is, “It needs a recharge,” and maybe it does. But when they bring the vehicle to you, the first thing you should do is insert an auto A/C thermometer in the dashboard vent to properly gauge the air temperature. Most manufacturers recommend air coming out of an A/C vent to be 38 to 46 degrees Fahrenheit. Below that you can have a coil freezing condition. Above 46 degrees the system is probably not cooling properly. To properly diagnose, let’s take the process one step at a time.

One customer came in complaining their A/C was not blowing cold enough. After letting the air conditioner run for a few minutes, we found the air blowing at the correct temperature. Upon further discussion, we discovered their black car (with black dashboard) was parked in the sun at home and at work and trips rarely lasted more than ten minutes. So, before you take a temperature reading, make sure the A/C system has been running five or 10 minutes. If the vehicle has been sitting in the sun, the ductwork in the dash will have absorbed heat, and it may take a while for it to cool down and give a proper temperature reading. After running the A/C for five or 10 minutes, turn the blower to full blast. This will not only give you the coolest air, but you can see also if the amount of airflow feels weak. If it is strong, measure the temperature. If it is weak, the cooling problem may be a very easy fix, and this quick story will tell you why.

Years ago, I was traveling with a sales rep in West Texas cruising on the interstate in his VW Passat. You can imagine the hot, dusty environment in which he traveled between Texas’ major towns. After about 30 minutes the rep turned to me and said, “I apologize for the weak air conditioning, it’s not blowing like it used to. I have to get it into the dealer.” I asked how many miles he had on the car and he said there were just over 105,000. I then asked when he last changed his cabin air filter, to which he replied, “What’s that?”

We pulled into the next rest area, he popped the hood and then I opened the door on the top side of the firewall. I removed a cabin air filter packed solid with dust, bugs, leaves and other garbage. He then started the car (with the dirty cabin air filter removed), kicked on the A/C and yelled out, “You fixed my air conditioning!” We replaced the filter later that day. It would be nice if all A/C repairs were that quick, but keep in mind a regular cabin air filter replacement will help keep the A/C flowing properly.

However, if the system is blowing strong and the air coming out of the vent is hotter than 45 or 50 degrees, the system is probably low on refrigerant. There is only one reason any A/C system is low on refrigerant; there is a leak in the system. Most leaks are very small and occur over a long period of time. You may be able to service and cure this pinhole type of leak. But, if the system is losing pressure in a short amount of time, the leak is large and will probably require an A/C specialist to repair it. Before you attempt to recharge the low refrigerant problem, let’s examine the system and its needs.

Obviously, the refrigerant leaked out and needs to be replaced. Make sure you are using the correct refrigerant to replace it. In 1994, auto A/C systems began using R-134a refrigerant, replacing the old R-12. Today, most vehicles requiring A/C service are charged with R-134a refrigerant. However, new R-1234yf refrigerant was recently introduced and is gaining popularity with each model year. You will eventually see R-1234yf vehicles appear in your service station, but currently it is only found in select newer models.

Next, the system not only holds refrigerant, but it also contains an oil lubricant as well, known as PAG oil. The oil lubricates the air conditioning compressor, which is the heart of the system. When the refrigerant leaked, the lubricant leaked as well. The No. 1 cause of compressor failure is lack of lubrication. By only adding refrigerant, you may be slowly destroying the compressor, which could end up costing your customer hundreds of dollars to repair.

Replacing the refrigerant and lubricant will be a waste of time if you do not try to repair a pinhole leak. There are a number of leak-stop products on the market that repair minor leaks. Be cautious of the type of leak stopper, because one that contains polymers is potentially harmful to the A/C system. A polymer-free leak stop does not harden and is not affected by air and moisture. It creates a soft, pliable patch to stop small leaks in metal parts, and some expand rubber to stop small leaks in rubber parts.

There is one last item for consideration.

When you add the refrigerant, lubricant and leak stop to the system, the service should be complete and blasting cool air, unless the leak was just too large. If that is the case, the leak needs to be found. Injecting a UV dye into the system will pinpoint the leak. Simply shine an ultraviolet inspection lamp on the system, and the glowing dye will highlight the problem. It will show what parts in the system need to be replaced by a qualified A/C technician.

To repair a pinhole leak and recharge, the system needs refrigerant, oil, stop leak and a UV dye to complete the service. Air conditioning service suppliers offer products that provide all four elements in one aerosol can. Almost all contain the currently-popular R-134a refrigerant, a mid-weight viscosity lubricant, a polymer-free leak stopper and a U/V leak detection dye. There is no need to introduce the components into the system one at a time when all are included in one can. Eventually, we may see the four elements in a can containing R-1234yf, but today there is not enough demand.

Completing the service with one aerosol can is really quite simple, especially when you attach a reusable dispenser/gauge tool to the top of the can. This gauge reads the amount of pressure in the system and tells the installer when the recharge is complete. The gauge is color-coded, and it is an easy way to ensure the proper amount of refrigerant, oil, stop leak and dye are introduced into the system. Without a gauge, too little juice in the system will not provide optimum cooling, and an overcharge will not allow the system to cool properly either. If it is extremely overcharged, it could damage the compressor. The installer simply needs to recharge up to the colored area on the gauge specified by the manufacturer of the tool.

When the service is complete, you should be able to feel the difference in the cool air coming from the A/C vents. Re-check the cooling temperature with your vent thermometer. If the system is not cooling properly, it may have other problems the recharge will not fix.

That process was actually pretty simple, but the real key to successfully selling an A/C recharge service is to educate the vehicle’s owner up front about the variables that can affect the amount of work it will take to fix the problem. Be sure to include the following in your presentation to your customer:

·       Any consumer must understand that the service works most of the time, but not every time. The recharge/stop-leak is a low-cost alternative to replacing A/C system parts.

·       If the system is losing refrigerant, there is a leak. If the leak proves to be too large, an A/C specialist will need to repair the system.

·       If the system continues to lose refrigerant, the leak will need to be pinpointed immediately with an ultraviolet light and dye.

If your customers understand a recharge works most of the time, but not all of the time, expectations are realistic. However, if the customer requires a guaranteed repair, they should consult a qualified A/C repair technician who will locate and replace the leaking parts.

This process works and will help you make A/C service a valuable and profitable part of your business: make sure the cabin air filter is replaced regularly, use a thermometer to confirm the A/C system is not blowing cool enough and recharge using a gauge, so the correct amount of refrigerant chemistry is introduced to the system.

The service can be simple, as long as you properly train your staff on the correct procedures to follow, equip them with the right tools and products and communicate to your customers the proper expectations of each level of service.


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