It’s been decades since cabs on tractors, sprayers, swathers and combines were built with opening windows. They’re all sealed up tight and totally dependent on air conditioning.
When the air conditioning stops working, so does the implement.
Combines and swathers are especially vulnerable, with their wide expanses of glass and long hours in the August and September sun. It’s not a matter of if the air conditioning goes south at harvest time. It’s more a matter of when.
If you’re lucky, the licensed AC technician might get out to the farm the same day and you might get by with $300 or $400 for a rubber hose and a recharge. If you’re not so lucky, you lose a day or two of harvest and the bill is $1,000 or $2,000.
Read Also
Farming Smarter receives financial boost from Alberta government for potato research
Farming Smarter near Lethbridge got a boost to its research equipment, thanks to the Alberta government’s increase in funding for research associations.
What about those do-it-yourself hydrocarbon recharge kits for backyard mechanics? The big box parts stores sell them for $99 during the summer, the logical time to get top dollar.
But at this time of year, prices drop to under $50. That’s good timing on the price if you’re running combines, swathers and grain trucks.
The appearance of such a good deal made me curious about whether the kits really work and how easy it is to do the recharge.
I had converted my 1991 GMC pickup to DuraCool hydrocarbon in 2001, after which I experienced no problems with the air conditioning until a month ago when it started fading. But, I had enjoyed seven years with no AC repair bills, a pleasant change from the previous seven years when air conditioning repairs averaged more than $700 per summer in the old R-12 and R-134a systems.
Hydrocarbon trial
There are many brands of hydrocarbon AC recharge kits on the market. For the trial, I bought a Red Tek kit from the closest auto parts store.
During the summer, it listed for $99. It was advertised on sale last week for $79. By Aug. 18, it was $49, plus $15 for the can of Red Tek Leak Stop. Had I made my purchase over the weekend, the Leak Stop would have been thrown in for free, bringing the real cost down to $34.
The guy at the counter said the pressure gauge, marked in p.s.i., was a thermometer for the temperature of the refrigerant. That’s when I decided to use one of my help lines. I called a friend, Keith Berglind, who has taken the certification course from the Manitoba Ozone Protection Industry Association (MOPIA).
The kit includes a hose with a pressure gauge mounted on a T fitting in the middle. At one end of the hose there’s a handle valve to tap into the pressurized can. At the other, there’s a quick couple sleeve for the low-pressure service port. The hardware is not professional grade, but it does the job. The thermometer is not included.
The kit also has an oil analyzer plug that fits into the low-pressure port. Make sure you do the oil analysis before attaching the kit because if the oil is contaminated, your system needs to be purged and new oil added.
Smartly stab the stem of the analyzer into the low-pressure port. Expect to get squirted.
One quick dab of oil and the analyzer instantly tells you if it is tainted. If the analyzer turns white or yellow, the oil is good. If it turns more of a dark brown colour, the oil is contaminated and you need to change it before wasting fresh refrigerant.
Warning – Make sure you deal with the low-pressure port only. Do not access the high-pressure port with this equipment.
“When the system is at rest and compressor isn’t turning, both sides have the same pressure. But when the system is running, the high-pressure side might have enough power to literally blow up the can,” says Berglind.
“It happened to someone I know. He’s lucky to be alive today and not blind.
“If you aren’t sure which is the low pressure port, stop what you’re doing until you find out. These tin cans cannot take high pressure.”
Checking the lines on my GMC, I saw the high-pressure hose coming out of the compressor is the smaller of the two at 13/32s of an inch. The low-pressure hose is the larger, at 5/8ths of an inch.
“The liquid refrigerant is under pressure coming out of the compressor, so it’s confined to a small hose diameter. After it’s done the job of transferring heat, the low-pressure gas wants a larger hose returning to the compressor,” Berglind says.
Quick ‘n’ easy
Once you’ve read the instructions, the procedure is quick and easy.
Begin with the engine turned off. Attach the quick coupler to the low-pressure port, making sure everything is clean.
Screw the Leak Stop can onto the piercing needle tap as directed. Invert the can and open the valve on the needle tap so the fluid runs into the system. Watch the pressure rise.
Again, with the engine turned off, repeat this procedure with the first can of hydrocarbon refrigerant.
For the second can, the instructions say to start the vehicle. Once again, the entire contents of the can were drained into the system on this particular truck. On some vehicles with larger capacities such as combines and tractors, you may need to buy more cans to complete the recharge. On small vehicles, you may not need the second can.
Was the operation a success? I’d say so. In checking my cab vent temperature before we started, the best I could get was 24 C.
After the Leak Stop went in, the vent temperature dropped to 19 C. That’s because this first can contains a small amount of the refrigerant along with the seepage stopping chemicals.
The first can of Red Tek dropped the vent temperature to 10 C. The second can brought it down to 5 C. That’s my idea of what an air conditioning system should do.
Physics lesson
The benefits of hydrocarbon refrigerants can be found in a high school physics textbook. One hydrocarbon refrigerant molecule is 2 ½ times bigger than a molecule of R-12 and three times bigger than a molecule of R-134a.
The chief advantage of a bigger molecule is it doesn’t leak out as easily.
Another advantage is that it takes smaller amounts to fully charge a system. Back when R-12 was commonly available, it would take 10 to 12 pounds to charge a typical system up to optimum performance. That same optimal performance can be gained by only two or three lb. of hydrocarbon.
AC technicians explain this by saying that hydrocarbon refrigerants are more efficient at transferring heat.
Lubrication is another plus for the recharge system. Because hydrocarbons are petroleum based, they are compatible with both mineral and synthetic lubricants used in air conditioning. That’s going to keep the compressor running longer and should give the seals a longer life.
Hydrocarbons work at lower pressures, thus reducing failures of compressors, hoses and seals. That, along with the larger molecule, means a substandard air conditioning system may function longer with these refrigerants.
Hydrocarbon refrigerant blends remain in the atmosphere for less than one year. Compare that to R-134a, which stay for 16 years.
Hydrocarbon refrigerants are a blend of propane and butane, both of which have a rated ozone depletion potential of zero and a global warming potential of eight. R-134a has a global warming potential of 1,300.
Warning – Hydrocarbons are considered to be flammable and explosive, and can be dangerous under the wrong conditions.
Is it legal?
The hydrocarbon recharge kits are available everywhere, I reasoned, so they can’t be illegal. But maybe it’s best to check.
According to Mark Miller, executive director at the Manitoba Ozone Protection Industry Association, “hydrocarbons work quite effectively in any kind of refrigeration system.” He said DuraCool, Red Tek and the others are good products. And, yes, they are legal to buy and use.
“In fact, the United Nations Environment Program and Greenpeace advocate hydrocarbons for all types of air conditioning. If you’re repairing a system that has hydrocarbons, you can just vent them into the air. There is no need to recover them.
“The only concern we have is that a person might add hydrocarbons on top of R-134a or R-12. Making a refrigerant cocktail is definitely in contravention of the law.”
Miller said that if a R-134a system needs a recharge, then obviously there’s a leak that must be repaired in accordance with the regulations.
“Just dumping in hydrocarbons is not a permanent solution. You’ll have your air conditioning for a while, but it’ll fizzle out again sooner or later.
“The correct procedure is to have your R-134a or R-12 recovered by a licensed technician. Once you’ve done that, you’re free to run as much hydrocarbon refrigerant as you want and you can do it yourself. No restrictions.”
Miller said hydrocarbons are increasingly popular with farmers who need to keep their cabs cool. A switch to hydrocarbons gives the farmer free rein to install his own refrigerant.
But there is a drawback.
“Manitoba Public Insurance does not support the use of anything but R-134a. Even if you have installed hydrocarbon strictly in accordance with the regulations, and you’re in a collision, MPIC will not pay for air conditioning-related repairs.”
Does that mean MPIC will deny an entire claim if an air conditioning hose is ruptured and there’s a fire caused by the hydrocarbons?
MPIC staff we contacted could not answer that question.
