Building an A/C system from near scratch

[shumpertdavid]

Vacuum time won't matter at all unless the oil is good in the pump and not saturated.

There is truth in this also, good point.

[dee]

shumpertdavid, what's your thought on still adding a few ounces of Mineral oil to the compressor even though the R134 systems don't call for it? I out of habit still do this and have not seen any advantage or disadvantage either way. I've asked at several A/C schools and no one seems to say one way or the other all just say it's not needed, but my thoughts are that Mineral oil is "supposedly" too heavy to be pulled through the system with the refrigerant therefore it always keeps the compressor lubed.

[shumpertdavid]

Not sure on that one. I would be concerned that possible the dissimilar oils could react and have negative effects. That being said, I don't know anything about how they mix. You could pour a few ounces of each into a bottle and agitate it to see how they mix and separate. I know I've got some conversions still running, one my personal vehicle, that would have still had traces of mineral oil that have been running trouble free for years.

[dee]

I've mixed a few different flavors of pag and couldn't really tell much. Being I'm in fleet repair I get to see the particular vehicles or equipment again and haven't for any A/C related problems. I also have gone against the grain by not replacing receiver dryers/accumulators unless there is a catastrophic compressor failure or the desicant bag is ruptured, as long as a known good vacuum pump is used and the oil is good I've had no problems.

[shumpertdavid]

I wouldn't mix the viscosity's. The tolerances inside the compressors dictate the oil weight needed just like with bearing clearances in a motor. A motor needing 5w\20 for tight bearing clearance isn't going to like having 20\50 ran through it. As far as the accumulator\ receiver dryers go. Realistically they should be replaced any time the system is opened. I don't follow this as being in a small town area. But any major component replacement get one. The moisture absorbed in the desicant bag can never be removed, so once it's at it's limit @ 2 tbl spoons it no longer doing its job and at risk of the bag bursting.


For as cheap as they usually are, it's not worth the gamble on my part for the potential comeback. I try to repair my customers cars in the same manner I do my own (assuming they can afford it) and I don't want to do mine twice.

[dee]

I meant with the mineral oil not mixing various pag oils that can cause problems.

There's no way to not let desicant bag get moisture saturated if it was a lot larger maybe but as soon as the caps are removed It's saturated. A good known pump that will boil water fast and well will boil the moisture out, just cause the pump will pull the gauge down doesn't mean It's pulling that good of a vacuum on the whole system.

[shumpertdavid]

I meant with the mineral oil not mixing various pag oils that can cause problems.

There's no way to not let desicant bag get moisture saturated if it was a lot larger maybe but as soon as the caps are removed It's saturated. A good known pump that will boil water fast and well will boil the moisture out, just cause the pump will pull the gauge down doesn't mean It's pulling that good of a vacuum on the whole system.

I'm going to have to disagree with you on the desicant having moisture pulled from it. The vacuum will remove the (boil out) the moisture in the system, but physically won't pull it from the desicant. This was just explained to me in class by a company that builds them. As far as the vacuum pump goes as long as it's pulling 29.5" on the system, it's well adequate.

[dee]

I was told the opposite buy someone in the industry as long as good vacuum pump is used the moisture will be boiled out. I've done this on several systems some that have been open for over a year and none have ever came back. I wouldn't even hesitate to do this on my personal truck that's been open for over 4 years.

29.5" is all that's needed but just because the gauge shows it is doesn't mean it's actually pulling that hard through out the system. I've seen several vacuum pumps that couldn't boil water on a large mason jar that was setup sealed with a fitting in the cap but the gauge read 30" of vacuum, if it can't boil water in a jar it can't boil moisture out of a system.

[KBScobravert]

Quick question. Can the accumulator/drier be remote mounted away from the evaporator by up to a foot away?

I should have most of the hard parts in place today and ordering some hose ends tomorrow. It would be great if I could find someone to charge this thing next week.

[dville_gt]

Quick question. Can the accumulator/drier be remote mounted away from the evaporator by up to a foot away?

I should have most of the hard parts in place today and ordering some hose ends tomorrow. It would be great if I could find someone to charge this thing next week.

if they say it can't i'd still give it 50/50 it'll work

went and cruised the coupe yesterday with nice cold a/c with my sideways acuum

[KBScobravert]

if they say it can't i'd still give it 50/50 it'll work

went and cruised the coupe yesterday with nice cold a/c with my sideways acuum

Who charged your system?

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

[dville_gt]

Who charged your system?

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

buick355, first try we found out i didn't have a low side port...whooops, so i had to get one brazed in

[line-em-up]

...

I was told the opposite buy someone in the industry as long as good vacuum pump is used the moisture will be boiled out. I've done this on several systems some that have been open for over a year and none have ever came back. I wouldn't even hesitate to do this on my personal truck that's been open for over 4 years.

29.5" is all that's needed but just because the gauge shows it is doesn't mean it's actually pulling that hard through out the system. I've seen several vacuum pumps that couldn't boil water on a large mason jar that was setup sealed with a fitting in the cap but the gauge read 30" of vacuum, if it can't boil water in a jar it can't boil moisture out of a system.

That doesn't make sense to me. If there is 30" of vacuum on the gauge, then it should be equal throughout the system. You won't have 30 in one section and less in another. How is the water not going to boil?

[dee]

That doesn't make sense to me. If there is 30" of vacuum on the gauge, then it should be equal throughout the system. You won't have 30 in one section and less in another. How is the water not going to boil?

The gauge is the closest to the pump so it will show more. I'll try and snap a pick of the jar at work tomorrow and post it up after. Another thing that is needed is to regularly check your gauges for proper calibration, if you're just gonna charge off of gauge readings.

[shumpertdavid]

Quick question. Can the accumulator/drier be remote mounted away from the evaporator by up to a foot away?

I should have most of the hard parts in place today and ordering some hose ends tomorrow. It would be great if I could find someone to charge this thing next week.

Based on my understanding of how it works, I would assume it would be ok. I know some of the Tauras A\c systems ran the accumulator up near the headlamp with a line assembly that plumbed back to the evaporator, and they worked fine that way.