Freon swap

That’s the old original tech bulletins, Supposedly 134a eats regular hoses, and silicone seals. The recommendations were to upgrade to silicone hoses, and vitron seals. For some reason it only eats silicone seals, not silicone hoses.Lol. It’s a bunch of bull. I’ve done at least 5 conversions, on my Truck, and others. Never had a problem. Technically some minor seeping is probably possible. But never saw any problems. It was more of a HVAC industry, and Dealership moneymaker. Average cost to “ upgrade” being $1000, back in 98-99. Or do it yourself kit from Interdynamics, $35, included fittings, oil, and 134a. Worked great.

 

R12 used mineral oil, it won’t mix with pag oil. Suggested to use ester oil when doing a conversion.

 

I prefer to flush everything. Then you know it is clean and how much oil is actually is the entire system. Drain all the oil out of the new compressor ( or old ) dipstick the up rites, and measure what goes back in the system. Never trust the oil precharge amount.
No do not mix oil but there is a whole lot of vuduo smoke stuff people put out about A/C's
My 78 JD 4240's reman compressor is labeled mineral oil only. It is running mineral oil and R134A freon. One of the hoses going the the top of the cab look to be original. I have not added freon in two years.
I saw a lot of people just swap fittings, vacuum and charge R134A. Many got by with it. The ones that did not probably cost themselves a lot of money.

 

Whatever condenser fits the Truck. The problem with condensers and evaporators is that they’re almost impossible to flush. Oil and trash from compressor failures stay in them, because of the header/ fin design. They’re not a closed loop. Some will remain in the evaporator, but the ester oil is compatible, with the old mineral oil, and 134a. I would not even replace it, unless it’s full of trash from a previous compressor failure. I did my 92 WS, had all new lines, dryer, and condenser, when the compressor went bad. When I added up the cost to upgrade the compressor, and lines, it was a lot. My Brother in law, worked at Murray’s auto,( Oreillys now) He’s the one who called BS, and told Me the whole conversion kit, including 3-4oz is oil was on sale at the time. Bottom line, I replaced compressor with original type, it was cheaper anyways. Used the kit. Fittings, ester oil and 4-5 cans of 134a, it worked great for the next 2 yrs. then traded the Truck. If you’re going to upgrade compressor, you’ll need new lines, a condenser, and ideally new evaporators, might as well do expansion valves, I did my Freightliner 5 yrs ago, replaced everything, except evaporators. I flushed them forever, never fully ran clear. I should have replaced them. A new air dryer, hopefully cleaned up the residual trash from failed compressor. So far so good. Point being it’s expensive and a lot of work. Your compressors good, maybe. Probably have a leak somewhere. Fix the leak, Charge it up, with 3-4 ester oz oil. Correct amount of 134, see what you get. If the compressor hasn’t failed, systems still clean. You can take compressor off. drain oil, replace with same amount ester oil, if you want, It’s not an exact science, unless compressor, condenser, and evaporators are new. Too little oil, bad for compressor bearing, too much system runs hot, and won’t cool compressor. Better to have too little oil, than too much. According to Sanders literature. It might be 5% or 6% ideally. You can find out from Sandens website.

 

A few years back when R134a replaced R12 I did a large number of conversions. I was working for a KW dealer and their trainer told us that once an R12 line was used with R12 it would not absorb the R134a and would last. The same went for the seals. According to him if you installed new lines or seals meant for R12 they would deteriorate rapidly and start leaking. I was taught to drain as much of the R12 oil from the system as I could then add the correct oil for R134a and evacuate the system and recharge with 10% more R134a than the weight of R12 that was previously required.
From my experience the trainer was correct.

For quite a few years after R12 was gone Kenworth still used the same evaporator and condenser
cores in new trucks with R134a.

 

I was just reading up on Sandens website. They’re currently saying to evacuate, drain old oil, change dryer and just refill with standard 134a and oil. % of oil approx 11%.So 55 Oz system roughly 6 oz.

 

There are actual A/C flush products for this.
Alcohol from the hardware store will work but Mr Safety does not like it.
Guy I worked with used brake cleaner. Snapped a band type can tape on and ran it through the gauge set. That is not recommended but I never saw him have a problem because of it.