my A/C problems... gurus help me out, please

[hotghias]

i used search. i did learn some stuff, but it didnt answer my questions, so here goes...

on my 87 325:

2 months ago, on the prev. owner's mechanic's advice, i topped off the non-converted, low ac with 2.5 cans of "freeze 12". the mechanic had added freeze 12 to the car before, so it probably had a mix of that and maybe some r12. it cooled to 70 degrees at the vent in 85 degree weather. the slow leak was faster than i expected and the refrigerant was mostly gone in a month.

so, about a month ago, i pulled a vacuum pump on the low side, pulling 30 pounds for 30 minutes (car not running). i then added 1 can of 12 oz 134a with 4 oz lube and leak sealer from a conversion kit. the pressures read 40psi low and 200psi on the high side. (1) how did i get that kind of pressure with that little refrigerant? i didnt add any more than that one can because the pressures were good. it cooled slightly better than with the freeze 12, i think.

this weekend, it was down to 5psi on the low side, so i added another can 134a/oil/leak sealer. got me to 35-40 low and 200 psi high.

my pressures look pretty good, a little high on both sides if anything, right? so (2) I can't figure out why my air isn't frostier.

3) my compressor does not appear to be cycling, just running nonstop when the AC is on. why? is this b/c there isnt enough freon in it?

4) I am going to have to do something about the leak... i will soon be adding a 4-oz can of sealer with dye, to hopefully at least help me find it. what are common locations for leaks?

5) AFAIK, the system had not been opened, but it has been run "low" for sure. and i'm not totally happy with the cooling. do i need to replace the dryer? the expansion valve? the seals? (hopefully not) the compressor?

(6) EXTRA CREDIT: when you stop the car, the compressor continues to spin for a good 10+ seconds... in the opposite direction of its usual rotation. i guess the pressure in the high side is trying to get to the low side... but has anyone heard of this? shouldn't the pressure equalize by going through the other way, instead of exerting so much force as to turn the compressor? i'll check soon and see if it is just the clutch moving, or the clutch and the pulley (meaning stuck clutch, explaining the non-cycling).

thanks for any and all help,
evan

[DaN]

Well, first you need to find the leak before you do anything else.

Once you've found it, fix it.
Make sure the auxillary fan works.
Since you have two different kinds of oil (that arent meant to mix) plus sealer, plus dye, plus two different kinds of refrigerant. I would definitely recommend flushing the evap and condensor, changing the drier and expansion valve, and pulling the compressor to drain the oil.
Then replace the oil with some ester oil of the correct capacity.
Pull a vacuum on it for a few hours and fill it with the correct amount of freeze 12,and it should be good.

It's alot of shit to do, but you have soo much crap in the system, it needs to be done if you want things to work right.

[hotghias]

for the record, the oil in the 2 cans of 134a was ester oil, which is supposed to be compatible with the r12 oil, right? that's the only oil/sealer that's been added thus far. and i sucked all the old freon out before i put 134a in it, so 134a is the only refrigerant in it. and 30 lbs of vac. should have boiled most/some/any water out, too.

the aux fan works well.

what is meant by flushing the evaporator and condenser? taking it out and blowing air through it or what?

where can you get the expansion valve? and what would be the reason to replace it? the pressures seem pretty good so i figured it was fine.

and again, see above questions. i still don't understand why it's not cooler, why the compressor isn't cycling, why it spins backwards, etc. and in particular, where should i look first for leaks?


thanks for the input so far, dan.

[DaN]

There are flush kits available, like this: http://www.thetoolwarehouse.net/shop/FJC-2710.html

Have you allowed vacuum to hold on the system for a while with the pump off, so any leaks show when vacuum is released?
I would change the expansion valve just because they are fairly cheap, and it may have some crap in its screen, not to mention the sealer and dye, etc. they have them at expressautoparts.com among other places.

It's not cooler because of the system contamination, and the high side pressure seems a little low, it may need more refrigerant. I had mine up to about 250psi at idle and it cools well.

Look for leaks in any place that has an oily residue around it, do you have the uv light to put the dye to use? Check around the schrader valves, all connections, compressor seal and the evap drain area.

I could be wrong but i dont think the compressor is cycling because its undercharged, so high side never reaches its peak.

My compressor used to spin backwards, I don't really have answer for this, perhaps someone will chime in.

[EverWiser]

If you didn't flush your old oil out of the system you've probably ruined your system or at least it will fail in short order. The oils may mix but the R134 turns the old mineral oil the system came with into a black acid goo. It'll slowly eat up everything. If you flush it right away it might survive but you may have already done a lot of damage. Do a Google search for R134 conversions and you'll find out what I mean.

[hotghias]

http://www.epa.gov/ozone/title6/609/technicians/retrguid.html

"Flushing
The amount of mineral oil that can safely remain in a system after retrofitting, without affecting performance, is still being debated. It was originally thought that any mineral oil left in the system might cause system failure. As long as the tech has removed as much of the old mineral oil as possible, any residual R-12 left in the system should not have a significant effect on the performance of the system. Removing the mineral oil may require draining certain components. Unless the vehicle manufacturer recommends flushing the system during the retrofit procedure, a service tech can assume that flushing is not necessary. (Although the SAE J1661 procedure for retrofit includes flushing, SAE no longer believes that flushing is critical to a successful retrofit.) "

http://www.dupont.com/suva/na/usa/literature/pdf/h75326.pdf

recommends removing about 95% of the oil for max proper operation, but doesnt mention black goo.

i'm hoping you are misinformed, EverWiser, and that i don't have much to worry about. i have no doubts my system would perform better if i drained the old oil, and i will probably end up doing it, but i havent read anything definitive about damage from non-compatibility. can anyone confirm?

when i had the vacuum on it, i closed the system and let it sit there with nearly 30 inches of vac in it for a few minutes and didn't see any movement.

as for the compressor spinning backwards... ok, as long as mine isn't the only one, i'm not concerned.

[EverWiser]

Hello hotghias....I did another search and I can't seem to find the link(s) I was referring to. I apologize if I mislead you. I did this conversion on an ex's '89 525i (3 years ago) and I had come across info that was posted on the "unofficial" E34 board that led me to the information I was referring to. After going back to their page and checking all of their AC related articles I can't find the same info again. Maybe it's been deleted due to having been outdated/disproved since then (as you mention in your post). However, they still recommend draining the compressor (which requires removing it), replacing the expansion valve and drier, and flushing the evaporator, condensor, and lines. I stand (actually sit) corrected. Good Luck!

[Spaz]

btw, do not flush your ac lines!

u can flush your evap, condensor. but nothing else.

also drain and refill the compressor with the proper oil.

[EverWiser]

Hey hotghias, I found this link with a lot of good info. http://www.ackits.com/forum/index.cfm Enjoy!

[325beast]

Post your question on the forum @ www.aircondition.com. Tell them the pressures/equipment/temp readings.

Hands down the best AC site I've come across.

[hotghias]

Post your question on the forum @ www.aircondition.com. Tell them the pressures/equipment/temp readings.

Hands down the best AC site I've come across.

haha, what are the chances... i just did today... about the oil compatability.

here's my plan: once this charge leaks out i should be hunting down and fixing the leak, replacing the dryer, and maybe the expansion valve, replacing the oil with ester oil, pulling a vacuum, and refilling with 134a.

how do you replace a reciever/dryer without exposing it to air? and how is it shipped? i guess the time you are installing it doesnt affect it?

[EverWiser]

how do you replace a reciever/dryer without exposing it to air? and how is it shipped? i guess the time you are installing it doesnt affect it?

As long as you pull a good vacuum it shouldn't matter. It only comes shipped with little plugs to keep dust/dirt out; it doesn't arrive pressurized or anything like that so I wouldn't worry about it. Just pull a good long/strong vacuum on the system after you close everything back up.

[hotghias]

how do you replace a reciever/dryer without exposing it to air? and how is it shipped? i guess the time you are installing it doesnt affect it?

As long as you pull a good vacuum it shouldn't matter. It only comes shipped with little plugs to keep dust/dirt out; it doesn't arrive pressurized or anything like that so I wouldn't worry about it. Just pull a good long/strong vacuum on the system after you close everything back up.

Hm.. i thought you had to replace the dryer whenever you exposed it to the atmosphere. why is it necessary, then, to replace it whenever you crack into the system? is it just a precuationary measure since they go bad over time?

[EverWiser]

I've never heard the "everytime" you crack the system. I think it's just a matter of fact that the majority of AC systems don't get "cracked" very soon after their manufacture and by the time they do you might as well change the drier to insure you've got fresh dessicant. Moisture will destroy the compressor as well as eventually cause internal corrosion of the system so if the system has been depressurized or "open" for a long period of time I'm sure the dessicant will be "saturated" and need replacing. If you've just replaced it in the last 6 months and still have some pressure in the system and you're not changing the type of gas/oil that you've been putting through it I wouldn't worry about it. If in your case you've had old and new gas/oil cycling through it, I'd change it again just to be safe, but that's just me.

[hotghias]

Thank you all for the great responses and help.

another question:

which reciever/dryer? i heard some mention of someone using the e36 dryer. plus, there is an early and a late e30 dryer. is one of these 3 designed for 134a? the later e30 dryer (not the one i need for an 87) is cheaper but requires a different (and more expensive) switch. is there an advantage going to the later or e36 unit?