AC Resurrection
 

Hi fellas

It's been a while since I posted on this great forum, I still see a lot of familiar names, and I visit frequently to read up on interesting issues, however I've been busy with other projects, and my Benz gets reduced attention these days.

I'm here seeking advice as I'm faced with a difficult problem.
I've been working away on my 1985 190E 2.3 fixing and rebuilding components, and I'm at a stage where I want my AC working, since I'd like to drive the car during summer time. I set out to resurrect the system which has never worked while the car was in my possession.

I started out by doing a compressor rebuild. Amazingly it looked really good from the inside, no rust, everything clean, one piston had a few small scores, but I'm not considering a new one yet until I see how this one performs. All orings replaced, new condenser, even though the old one didn't leak, it was rotted, and it's days were numbered, so I replaced it. New drier, not installed yet. I got a vacuum pump and gauges too so I can service the AC on my other cars as well.

So, I put everything back together, and pulled a vacuum, things looked good, but after a few days the system sprung a leak, and now after about 30 minutes, all the vacuum vanishes, so it's a big leak, but not big enough to easily find.

I set out to search for a DIY way to find this leak. I tried filling the system with compressed air and spraying things down with soap and water solution to see if something would show. This should work, but not everything is accessible, so I did not find the leak this way so far, I keep trying but this might not be an optimal way.

My next option is a UV leak kit, this should work, but I would have to load up the system, and run the compressor before all the refrigerant escapes. Problem with this approach is I don't know if I won't be doing damage to any of the components by forcing the system on, if it even starts, but I am considering it, I just need to do a bit more wrenching and put everything back together before she starts up.

I heard of a way to use nitrogen to find leaks, but I don't know exactly how this would work, or where in Canada a DIYer could get his hands on a Nitrogen tank.

Sniffers are out of the question since they are a lot of money, and there is no refrigerant in the system to sniff.

I can also start replacing everything, but lets say I'd rather find the leak first, and replace only what is necessary instead.

I'm wondering if anyone dealt with a similar issue and could share their experiences with difficult to find leaks and an AC system in a not exactly working state.

Appreciate any input fellow enthusiasts.

xp

Odds are that the leak is in someplace that you cannot easily find with the soap/water method.

Did you check the valves? I had a leak there and it was hard to find because I always had guages hooked up and that hid the leak from being detected.

The only leak I've had so far since new on my '93 190E was at the expansion valve. I replaced the O-rings, pulled a vacuum, charged with R-12 and it was good to go.
I found the leak with my trusty old propane freon leak detector. You fire it up and when the hose detects a leak the flame turns green.

The valves are one of those hard to get to places, I can see the one side just fine, but the back, not so much. I was concentrating on that area last night, and I did not see any leaks, but there is only so much you can see with a mirror and flashlight.

I'm leaning towards jumping the clutch on the compressor only to have it circulate the dye around the system. Maybe I can manage to get that done tonight if things work out well. This leak has been driving me mad, and I can't give up now when the whole thing is so close to working again.

I heard of the propane/freon leak detector, I don't have access to this device.

xp

It may be the evaporator of course...Best option would be UV dye check it then pull back carpets and see if you can spot anything.

I set out last night with bubble formula to find the leak. In the process I opened up some connections, re-lubed the o-rings and closed them back up. To my surprise, this morning the vacuum was still holding. Maybe I fixed it after all. I'll let it sit over the weekend and check on Monday where things stand, if it still holds, I'll put in a new drier, pull vacuum and charge with cheap-o Canadian refrigerant.

If that does the trick, I'll have a nice and cool summer car.

xp

OK, I'll bite.....what is cheap-o Canadian refrigerant?

Cheap-o Canadian refrigerant is a mix of propane/butane made by a few companies.
R12, or R134a is illegal here, car dealers may have it, but they charge $150 for a recharge and they won't tell you what they put in the system. A car can be brought into Canada with R12 or R134a, but once it leaks out, you can not legally top it off in Canada.
For the time being I will run the propane/butane mix, just to make sure the system works. Other than being flammable, it works quite well and our government didn't ban it yet.

xp

let us know how the propane/butane mix works. I have been thinking about use that when I run out of r12. Some people told me they would be afraid of using a propane/butane mix as it is flamable. But so is r12 and r12 puts of leathal gas when burned.
I am not sure but I think most R12 replacements like jonsens freeze 12 is a propane/butane mix. I really do not want to do a 134a conversion as they never worked well.

So what refrigerant is legal in Canada and comes in new cars?

Freeze 12 is a mix of R12 and R134a, I wish I could get that down here.
All we can get in Canada is RedTek stuff:
RED TEK

and variations of it.

I'm not sure what cars made in Canada get in their A/C, I heard that some new refrigerant is supposed to be taking over, but it's not all that great either. Even the stuff they use for home A/C is no longer legal.

xp

Wrong answer
 

No it's not. It's about 75% r134 and 25% 1-Chloro 1,1-Difluoroethane
75-68-3. No r12 in it.

Right, it's a blend of R134a, and R142b, but back to the issue at hand.

Replaced the drier, and the leak is back.... very frustrating.
I'll fill it with refrigerant and dye and hope for results.

xp

I got the compressor running last night, it looks like my new front seal is leaking. A lotof oil with dye was thrown all over the front end, back to the drawing board I guess.

I wonder what went wrong with that seal, it's a funny carbon thing, I'm not even sure how it works to seal that well. At least I know all the relays are working, and the compressor was actually running real quiet, couldn't even tell it was on, didn't cool much though, but I wasn't expecting miracles, I guess I'll sort that out later.

xp