Wednesday, July 2nd, 2014

Beating the Heat with Air Conditioning

Electric Cooling Fans

Electric Cooling Fans

Believe it or not the first air conditioner for a vehicle goes way back to the times of horse drawn carriages and buck board. The A/C controls were a block of ice a small fan driven by a belt that was wrapped around the front axle. That is the first of the control system that is involved with air conditioning, the first of the creature comforts.

Update to the 1950’s and ‘60’s when vehicle air conditioning was a sign of luxury. Only the top of the line vehicles even offered this as an option. Air conditioning in middle of the road vehicles was the epitome of decadence, almost as impressive as being the first person on the block to have a color television. Up to then it was strictly 2/60 air. That is 2 windows open at 60 miles an hour.

Back then the staple refrigerant was “Dichlorodifluoromethane” gas which was made and patented by DuPont, and shortly gained the name as “Freon R-12”. This quickly became the most common name in the automotive A/C business, probably because most people couldn’t pronounce the full name of the gas.

AC Tools and Components

AC Tools and Components

With Freon as the cooling agent and cool air as the only requirement in the 60’s there were precious few control systems. An on and off switch and either vacuum or cable actuated mode doors and that was it. Shortly air conditioning became the norm and not the option starting in the mid to late 70’s in the sun belt.

By the way, that is where we live, in the sun belt. In the northern hemisphere air conditioning was still mostly an option as it was pretty expensive to purchase. The A/C units of that generation were huge systems and extremely heavy.

The compressors were big cast iron pumps and they all utilized extra-large cooling systems consisting of an oversized radiator and a new development, cooling fan clutches. But then came the “gas shortage” or oil embargo. Big heavy cars were not popular anymore because they inhaled fuel, and when your big old truck was only getting 9 miles to a gallon and you were restricted to buying 5 gallons of fuel at a time your radius of travel was limited at best.

Now vehicles were being made smaller and lighter and those big A/C systems had to be made smaller and lighter, which opened the door to controlled cooling. Controlled cooling initially was limited to smaller refrigerant capacities which required more efficient air flow and tighter modes of operation. Mode doors were developed to include recirculation modes so that you only had to condition previously conditioned air.

Compressor run cycles were designed to turn the compressor off under heavy acceleration or when air flow was restricted or Freon capacities were low or under charged so that the engine wouldn’t labor and burn more fuel. Belt driven cooling fans with heavy fan clutches were replaced with electrically operated fans that only ran on demand. Some vehicles had as many as three of these fans to cool not only the condenser but the radiator also.

The death blow to R-12 was twofold. DuPont’s patent ran out and the newest calamity “GLOBAL WARMING”. Yes the refrigerant that we all new and respected became banned by the world, slowly at first but newer vehicles were coming equipped with R134a, a newer safer type of refrigerant that did not cool as well as R-12 but close, and with every new invention comes new tools new technology and more controls.

The refrigerant capacities of a full size Cadillac went from 6lbs of gas to 2 lbs. Or since we usually refer to capacity levels in ounces, that meant the capacities went from 96 oz. to 32oz. With the price of R-12 right at $4.00 an oz. to R134a at .99an oz. that’s a big chunk of change.

Just some of the newest control systems that have been introduced in the last few years are, combined heating /air conditioning controls the use both the heating and cooling properties and combining them to get the driest and exact temperatures demanded. Wobble plate compressors that can adjust the amount Freon compressed as needed to acquire a set temperature.

Electronically controlled mode door that counts the steps (teeth in a gear) to keep a blend door at a precise position to get a precise temperature. Now we have both in the vehicle and outside the vehicle ambient temperature sensors to measure the temperature and humidity in the vehicle and outside so that the vehicle can be kept at the proper levels of coolness.

What else can we ask for? Well, maybe we didn’t ask for it but we got it anyway: as of 2014 a new Freon has been developed, it’s code name is R1234YF. Now when my Brooklyn comes out I call it 1234 you’re f*****d. But the point is if you remember that Cadillac that took 96 ounces of Freon, the new ones will be using less than 12 ounces. This means more tools, more schooling, and a higher cost to you as a consumer but they tell us at school that this is the wave of the future, well we’ll find out!

So here it is we went from a block of ice to 10 ounces of a super refrigerant, and we stay cool and dry and comfortable. Isn’t science wonderful?

Stay cool and calm and if you have any questions don’t hesitate to contact us at 941-575-8868 or just stop in, we’re always glad to meet you.


Gregg’s Automotive Maintenance & Repair Center

236 S. Tamiami Tr.
Punta Gorda, Fl. 33950
Auto Repair, A/C Repair, Oil Change, Brake Repair & Transmission Services