Not always. Some AC fitting tubes are smooth / near smooth for easy hose assembly and the ferrule is locked / crimped to the fitting with the shape of the crimp mimicking a " barb " or " rings " , this prevents hose blow off.

Hydraulic hoses fittings are built this way as well.

Old style field install hose fittings have barbs to prevent hose blow off when used with a screw clamp. " AC " spec hose clamps have a leg that gives proper spacing so pressure is applied to a smooth area just past the barb. Standard non leg clamps are fine if the spacing is properly set.

When replacing factory ferrules with crimped on ones, be sure that the ferrule is crimped to the notch on the fitting.


RE: R290 = " propane "


From Lindie a major industrial gas supplier.

R290 (CARE 40) Propane | Linde Gas

MSDS / SDS sheet.

http://www.refrigerants.com/pdf/SDS%20R290%20Propane.pdf


I would not use R290 in a mobile application, propane would be hazardous in a crash that punctures the system. It would be fine in a household fridge, the chances for a sudden leak are low and the system volume small compared to a car.

Agreed. Removing the old rubber and ferules and then clamping on new hose (must be metric) with any kind of clamp will allow the hose to blow off. This is especially true when using 134a, as the pressures are higher than R12 or Hydrocarbon refrigerants. I use new steel beadlock fittings in all the hoses I make. If I am using a factory metal manifold or pipe, I have a barb welded (brazed) on, and crimp my own hoses on.

__________________

All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html

Getting deep and heavy - I like it. I feel confident that I can't get better advice and quality knowhow on AC anywhere else.

Question - I know there must be a good answer to this but I'm curious - why can't one pressure test with just plain air instead of nitrogen? I understand you don't want to introduce moisture - but if the system is empty/open and you are going to replace the receiver drier and vacuum soon after - is there some really clear reason one can't use compressed air? I've seen youtube videos of this - but of course the comments are just a bunch of people screaming at each other.

Where does one regular joe like me get nitrogen, is it expensive?

__________________
Andrew
Montclair, NJ
--------------
1982 300D Turbo
120k
Petrol Blue Green

Compressed air would be fine in a pinch if it was completely dry, getting completely dry air is the difficult part. Compressed bottled nitrogen is dry making it convenient. For the DIY guy, use R132 since it is convenient and won't harm R12 system. A nitrogen bottle ( of various sizes ) can be rented from a welding supply place but that gets to be more $ than a can of R132.

Pulling a vacuum on a system is a valid first test for leaks. If it can't hold a vac for a few minutes, there is a large leak.