Mechanics

FLUSHING AN UNCHARGED A/C SYSTEM THAT HAS SATUP SENCE '05

1993 Ford Aerostar • 6 cylinder 2WD Automatic • 92,000 miles

I know what I'm doing it's just that an A/C person told me I did not have to flush it since the vehicle has setup since 2005. Do ya'll think I need to flush my a/c system to convert it from r12 to r134a? If so can I use the flush kits from some where like Pep-boys or O'Reilly? It has the rear a/c also. It's not charged now either. THANKS YA"LL FOR ALL THE GREAT ADVICE & THE TIME YA'LL PUT INTO THIS SITE ! I thought this was a great site until ya'll asked for money for me to get an answer. If I had a job I would & will ALWAYS pay for help but ya'll are 100% WRONG to not answer my question without my paying !
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Michael b.
June 5, 2011.



We answer lots of questions for free but it's apparent to me that you are not experienced enough in refrigeration and how to retrofit to be able to perform this yourself without the risk of personal injury or serious damage to the system.

Wrenchtech
Jun 5, 2011.
Unless something has changed recently, you do not have to pay for an answer, and I like it that way. The only time you won't get an answer is if no one knows it or your description is unclear.

If your system was open as in air was free to circulate, there can be a corrosion problem from the moisture in that air, but that's why we pump it into a vacuum first to boil the water out. Flushing is more important when the receiver drier comes apart and lets the desiccant circulate. That can plug the expansion valve. Otherwise flushing is not commonly done.

The important thing when retrofitting is to get the old oil out. When we first started doing these, we were told we needed different hoses with nylon liners because the R134 molecules were smaller and could leak out easier. The compressor had to be replaced because we needed higher pressures to get the needed efficiency. The new hoses could handle those pressures. Nothing was said about the condenser handling those higher pressures. Eventually we figured out all those new parts weren't needed. When I retrofitted my '88 Grand Caravan, all I did was unbolt the compressor so I could turn it over to drain the oil, and screwed on the adapter ports, evacuated the system and filled it up. We no longer replace hoses or compressors. System efficiency isn't a problem because it still goes by temperature in the evaporator, not pressure. If the temperature isn't low enough, the expansion valve just lets more refrigerant in. I didn't even worry about the residual oil in the rear evaporator and hoses. I just filled the compressor with the new oil and let 'er rip. Worked very nicely.

Caradiodoc
Jun 5, 2011.
I am sorry I thought ya'll would not give me an answer without a donation. I've worked on ALL my a/c's over the past 25 years & 5 different vehicles. As always I try to get advice from at least 3 people IF I'm not 100% sure. I know that on a home a/c you better not add the new refr. Without cleaning out ALL the old r-22 are it may blow-up. I wasn't sure if the r-12 was like that are not. My system has been close tight I think. It must have a little leak are it would've stayed charged I guess. I will find the leak if there is one & fix it first. So your saying if I had a system that uses r-12 and it is charged & I want to change to r-134a just discharge the system & without cleaning it out put the r-134 in, right. Again thank ya'll vary vary much, & I' very sorry.

Tiny
Michael b.
Jun 5, 2011.
He didn't say that. All the oil has to be removed and replaced with different oil. Do you know how much charge a retrofitted system should have?
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Wrenchtech
Jun 5, 2011.
Head to a salvage yard first if there is still some R-12 in it so they can suck it out rather than letting it fly into the atmosphere like we used to do. It's valuable to them for recycling. Then drain the old oil out. Some people do say to flush the system to get more old oil out that has been circulating in the system, but most people don't bother to do that. If anyone tells you differently, I would believe them over me.

Refill the compressor with the newer "PAG" oil. Add the different ports to the high and low side fittings, then suck 'er down and fill it like normal. Fill it according to the label. There will likely be a sight glass on the receiver-drier, but they will still have bubbles on Fords when the system is full. You will never get rid of all of the bubbles regardless how much you over-charge it.

Caradiodoc
Jun 5, 2011.
Howdy Wrenchtech. Sorry I keep posting over you. I guess I just take too long to type! Hope you're having a dandy day.

Caradiodoc
Jun 5, 2011.
There are no sight glasses on any CCOT systems.

Wrenchtech
Jun 5, 2011.

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