reason for changinig feron??

[Dinkydow]

I have finally found some one who will service my Q the way I want it done. I do want to check with you guys on a couple of things. I would be having the transmission , and power steering serviced at a transmission shop in Thunder Bay, Ca. He told me they drop the pan take the screen out then flush the transmission without the filter in, then when it is flushed they put the cleaned filter back on. I asked if I could have a new screen put on, he said yes but it is a waste of money??? I asked if he could change the furon in the ac, he said why is it leaking I said no I just want it changed he said it is a sealed system and it will last a life time unless it starts to leak somewhere. My question is after reading alot of the messages on this forum I believe I do want it changed but can you help me with why?? Dumb question I guess but I really don't know. Also he said they use havoline synthtic trans fluid if I pay the difference. Any opionions on Havoline synthetic atf?? Thanks Wayne

[DAEDALUS]

I tend to agree with your tech on the freon. The AC is a sealed system. And it is under pressure. There shouldn't be any possibility of air or moisture getting into the system if the pressure inside is higher than the pressure outside. On rare occassions, the compressor can create a vacuum on the low side, allowing air to permeate (VEEEERY slowly) through the hoses, but I believe it is to a very small extent. Air won't harm the system, though it will decrease its efficiency. Moisture (in the air) is bad, as it forms an acid inside the R-12 system, destroying the compressor over time. That's why the system has a drier that contains a dessicant. It's a cost/risk issue. How much would it cost to change the freon and the drier? How much would it cost to do all that PLUS flush the system AND change the compressor? You could change the freon now, but considering the age of your car, your compressor could go in a couple of years, and you would have to do the whole shebang then anyway (freon, flush, compressor, drier).

[AZhitman]

To comment on the trans issue: No need to "change" the trans filter, as it's super easy to clean well. I replaced mine, but once I saw the old one (it was PERFECTLY SPOTLESS @ 90K), I was a little disappointed that I spent the $$$ on a new screen.

[PalmerWMD]

AZ:

Dennis has done experiments by cutting open the old ones that, cleaned look real good.And he posted that they are dirty inside.Based on that info, I dont think you wasted your money and I recommend changing them to new.

I always do.

Fred...

[Q451990]

I also wouldn't have the transmission flushed with no screen in place! You run the risk of loosening up some crap that would normally be caught on the filter screen and lodging it somewhere else in the transmission.

Flush first, then drop pan and replace the filter screen. It costs a few extra quarts of fluid, and some extra labor, but it's well worth it. The filter doesn't cost much so why skimp on it! As Fred said, Dennis has mentioned that the junk in the filter is often times not visible from the port. Replace the o-ring, gasket, and screws with the new filter.

Heath

[Q451990]

As far as the A/C freon replacement, there are mixed theories on that... it's very difficult to keep a mobile system perfectly sealed, so moisture can cause acid to form in compressor. The idea is that vacuuming the system out and then replacing the oil will replenish the oil in the system, but you're looking at two new dryers to do the job properly, and some expensive equipment to get it right... I'm probably a little more on the "if it ain't broke, don't fix it" side of this fence, but if I had the tools to do it in a cost effective way, I probably would.

Heath

[Q45tech]

The freon is not changed just vacuumed out run through dryers/filters in machine and used again.

The reason you pump it out is to weigh the actual charge [1.10 kilos- 2.4 pounds] looking for leaks! If not perfect [may take 30 minutes to suck out 97% of it.

The dryer is also a filter to protect the compressor.

The lube oil is what changes and becomes acidic and eats the evaporator insides causing most leaks and a $1500 bill.

These things should be flushed at first 60k then every 60k if you want them to last to 200,000 miles...........most fail in the 90-120k range because nothing was ever done.

The biggest risk is just doing a minimal [what failed] replacement with out a total disassembly and flush...........leaking failed metal in all the other components