Archive for August, 2015

Why “A/C in a can” is a bad idea.

Saturday, August 15th, 2015
airdrie auto air conditioning

This is an example of an “auto parts store” A/C recharge kit.

By Chris Dekker

 

Air conditioning refrigerant, sometimes referred to as “freon”, is the liquid that circulates through your car’s air conditioning system and makes the system cool. The refrigerant that has been used in vehicles since 1995 is called R-134a. Your refrigerant should theoretically never need topping up or changing, but the reality is that it can sometimes leak out over time, and your vehicle’s air conditioning may start to work poorly. (If a leak is found, it should be repaired, of course!) This post explains why an increasingly popular air conditioning “solution” is actually a bad idea.

While browsing your department store, you may have come across small cans of aftermarket, hydrocarbon-based refrigerant for sale, including brands like Duracool, Red Tek, and Emzone 12A. Should you use these products to “top up” your air conditioning system, and get it cooling well again? These products claim to offer better cooling (because they are a more efficient refrigerant), and be easier on the environment, so it sounds tempting. They’re cheap, too. While these claims are partially true, there are a bunch of reasons why you still shouldn’t put them in your vehicle’s A/C system:

 

Reason #1: You can’t recharge your system properly.

A proper, long-lasting air conditioning recharge procedure includes the following steps:

  1. Evacuate the old refrigerant from the system, and weight it to determine if the system was over, or under-charged.
  2. Measure the amount of oil that was removed from the system.
  3. Using an electric vacuum pump, pull a vacuum on the system for at least 15 minutes to draw out any trapped air, and boil off any water in the system. (Water boils at room temperature when under a vacuum!)
  4. Leave the system under vacuum for at least 10 minutes after stopping the pump, and monitor rate of vacuum drop to test the system for leaks.
  5. Add the appropriate amount of oil to the system. There is a minimum amount of oil required to protect system components; but too much oil will insulate the lines and reduce cooling.
  6. Charge the system with a specific weight of refrigerant. Too little refrigerant will result in poor cooling, and too much will create high running pressures, also causing poor cooling.
  7. Run the system and monitor high and low side pressures; temperatures; cooling fans, etc, to make sure everything is working properly.
  8. Add an ultraviolet dye to the system, so if any leaks develop, they can be located with a UV light and glasses.

The “refrigerant in a can” kits only address step #6, and poorly at that. There is no way to accurately measure how much refrigerant is added, and no way to pull all the air out of the system before adding it.  This means you are injecting an unknown amount of one refrigerant on top of an unknown amount of a different refrigerant (plus any air and water in the system), with an unknown amount of oil. It’s not hard to see why the results are often less than stellar.

So what happens if you try a hydrocarbon-based refrigerant, and your A/C still doesn’t perform as desired? Maybe now, it’s time to bring your car to a professional. But that brings us to problem #2…

 

Reason #2: Once a hydrocarbon-based refrigerant is added, most professional mechanics will not touch your A/C system.

What’s an azeotrope? It’s a mixture of  two different refrigerants, which when mixed, exhibit unique and undesirable properties. By adding a hydrocarbon-based refrigerant to the haloalkane factory refrigerant, this is what you create. This mixtures of refrigerant often behave unpredictably, and don’t function right in an A/C system.

Azeotropes cannot be disposed of in the same way that you could with a pure refrigerant such as R-134a. In Alberta, azeotropes are treated as a hazardous waste and must be disposed of at the Swan Hills treatment facility, at a cost of over $300 per pound. You can see why no shop would want to contaminate their R-134a tanks, or their A/C equipment with a hydrocarbon-based refrigerant!

We (and most other businesses) use an expensive tool called a refrigerant identifier, before we hook equipment up to your A/C system. It lets us take a sample of the refrigerant in your system, and analyze it to find out what chemicals it’s made up of. If we find hydrocarbons in the system, we have to inform the customer that we cannot service their air conditioning.

 

airdrie auto ac

Here is our refrigerant identifier, taking a sample on a customer’s vehicle. This is a $3000 tool!

 

Reason #3: Hydrocarbon refrigerants are flammable.

That’s right! Most of these “canned” refrigerants are made up of a light hydrocarbon such as propane. Propane actually has the right boiling point to make an excellent refrigerant, if it wasn’t for the safety concerns involved. In the event of a front-end collision where the air conditioning condenser or hoses were punctured, high pressure refrigerant spraying out at over 100 PSI could cause an inferno in a matter of seconds if it comes in contact with something hot under the hood. The chances are low, but this situation is certainly possible, and does happen. Refrigerant vapour under the hood can even be ignited by a leaking spark plug wire.

 

The “A/C in a can” solution is tempting for somebody who doesn’t know better: it’s quick, easy and cheap – but as you may now understand – could end up costing you a whole lot more than just servicing your system properly in the first place.