Alrighty, I tried to turn on the A/C today for the first time since I bought the truck, (stupidly didn't think about it when i was test driving it 5 times) and i suddenly realized that my A/C doesn't blow very cold. I realize that means i have to convert the system to R134 from R! if I want to fill it. How much is this going to cost about???? Also, is there any harm in trying to do the conversion myself with one of those kits from the auto parts store or wal mart??? Thanks for your responses.

Derek
93 Bronco XLT, 302

 

Those kits are geared toward GM products, so they don't include the correct oil for Ford compressors (PAG-42; not PAG-100 or ester). A good commercial parts store (like CarQuest, NAPA, Parts Plus, or a local one - not the Zone , Advance, or O'Reilly) will have a better "kit" than the off-the-shelf ones like WM. You also need GOOD instructions, a 16oz bottle of flush, a new orifice tube (red), a compressed air supply (to blow the flush thru all the components), a NEW accumulator/drier, and a vacuum pump to evacuate the system for at LEAST 1/2 hour.

Expect to pay $100-200 if you want it done right the first time. A set of gauges will be another $100, and it's a good investment if you plan on maintaining your A/C from now on.

 

Check out this

I've had a truck running on this for 3 years with no problems.

I've converted several using this kit.

 

"mineral oil used in the R-12 system ... forms a protective barrier, protecting {the rubber hoses} from the R-134a"

So what does that mineral oil do to the dessicant? 'Protects' it from the R-134a, so any moisture in the refrigerant STAYS in the refrigerant.

"...use whatever oil the compressor recommends..."

Ford compressors need PAG-42.

"The EPA refers to a 'Least-Cost Aftermarket Retrofit' in which the system is not opened and there are no major component changes."

OK... What reference do they make to it??? Do they say something like, "It's a terrible idea and you should never do it"?

"Ester ...{oils} are much less hygroscopic, which means that they don't absorb as much water from the atmosphere as PAG Oils do."

If your refrigerant oil is exposed to the atmosphere, the amount of water it's soaking up is the LEAST of your worries. PAG is a better lubricant for LOTS of reasons. Use PolyAlkaline Glycol for ALL vehicles, and use the correct viscosity. 42 for Ford.

"The mineral oil just finds a low place in the system, where it stays... The mineral oil does no good, but it does no harm. It's just there."

It 'stays' because exposure to R-134a causes it to gel. And the gelled oil that's in the compressor displaces the new oil, preventing those compressor parts from being lubricated. It can also block the evaporator, condenser, and orifice tube.

"Add 1 can of R-134a refrigerant first, so the compressor is not running 'dry'. "

The compressor is NOT lubricated by the refrigerant, so that's ludicrous. Plus, with no pressure in the system, the clutch cycling switch prevents the compressor from running AT ALL.

"...flushing is not necessary"

Wrong. You need to get the mineral oil OUT.

"...we use less R-134a than the amount of R-12 in the system (80-85%). This keeps the pressure at the appropriate level."

That's so FAR from scientific, that it would take me a few paragraphs to fully explain why, but basically: the compressor makes the pressure - not the quantity of refrigerant.

 

I love it when someone knows more than the experts!

 

So exactly who are you calling an "expert"?

 

All I know is what I've done. And that is evacuate the system and pump in the 134, done it to a half dozen of my own cars and trucks and still have some running in the group after 5-6 years. If it does not work please don't let me know I'd hate to think I'm really hot when it feels so kool down here in South Florida.

 

The more freon added the higher the pressures in the compressor. The higher the pressure the higher temperature in the evaperature coil. Pressure relates directly to temperature in the evaperator coil. Therefore when you loose freon the pressure gets lower, and temperature, and the evaperator freezes up.

Look at R-12 and R-134 guages, the outer ranges are pressures, the inner ranges are temperature. R-12 and r-134 operate at slightly different pressures for the same related evaperator temperature.

Therefore quantity of freon does make a difference in pressure. If not you could just put a couple of ounces of freon and the compressor would make up the difference and you would never have to add freon when it got low the compressor would just make up the difference.

 

I'm not talking about the difference between an EMPTY system and a full one - I'm talking about the difference between a FULL system and one 80-85% full. Of course, if the system is on the verge of being totally empty, the compressor can't make enough pressure.

My point in that quote & my response was that with the right orifice tube installed (the RED one), you can put the FULL charge of R-134a into it, and have the FULL cooling capacity of the system.

Running less refrigerant means you can transfer LESS heat from inside to outside - imagine if you had a compressor & system SIZED for 85% the charge of our trucks - it would operate at the correct pressure, but it would cool the cabin slower, and to a higher minimum temperature.


I'm not saying doing it your way WON'T cool the truck - it will. But if the conversion is done the CORRECT way, it'll cool more, faster, and last MUCH longer.

 

We're only talking about a couple of ounces of freon. And from experience anyone can tell that a couple of ounces can make a difference of 10-12lbs pressure on the low side, which is the difference between 40 degrees and 52 degrees evaperator temperature, which is a lot of cooling difference.

I'm not saying that changing everything is not a good way to go, but this is a inexpensive, quick, AND SAFE way to convert to 134 and you're not the only one that just can't accept that.

I have a friend who was an engineer for Chrysler Air Temp, which was Chryslers entry into home AC. His company now does all maintenance for all the area franchaise stores for one of the national burger chains. He has had several freezer units on this conversion for at least 3 years running every day with no problems and working great. That's proof of it's worth to me. If it works in a freezer you will have no problem in a car.

 

If 15-20% is 2oz, then the whole system would take 10-14oz. Even if "a couple of ounces" means 4, the system would be 20-28oz. My truck uses 40oz. I've never tried to find out, but I doubt 2oz. low would cause a 10psi drop in the evaporator pressure, even if I didn't have an accumulator.

I know your way is cheaper & quicker, but from what I've read, it's a short-term fix that costs lots of extra money the second time around.

A freezer refrigeration system works at different pressures, duty cycles, flow rates, tolerances, operating environments, and physical proportions than the system on a motor vehicle - you can't draw any reasonable conclusions from comparing them just because they use the same refrigerant or similar conversion kit.

This debate is going nowhere, and I'm sure everyone else is getting tired of reading it. You have your opinion - I have mine. We've both presented them. I'm through with this thread.

 

Finally somthing we can agree on. They operate at lower pressures, therefore lower temperatures and all year round, not just summer, which it makes it a severe test for the jelling properties of the oil. They take much more care repairing due to the lower temperaturess. As an old instructor of mine said "look in the yellow pages and see how many more AC repair listings there compared to refrigeration repair listings".

You still haven't proved there is a 2nd time around. Just saying I've read it doesn't make it fact. Using it and having no problems makes it fact. I would be glad to read and learn if you could provide a study where experts have found it causes problems later.

It will make a very small difference but on a system, like most cars that hold 12-14 oz then it makes a significant difference.