Air conditioning hose replacement

[DMCMW Dave]

Most common leak overall - shrader valves.
Most common damage leak - hose rubs on the steering column
Most common installer error leak - hose melts on the crossover pipe
Other common leakers - O-rings at condenser, low pressure switch.

Not as common but we've seen a few:
Evap core (usually a fast leak)
Compressor bearing;
Return hose about every 5 inches for the whole length of the hose;
Either hose when some idiot replaces the gas tank cover screws with longer screws, or leaves out all the washers. Pokes nice 8 mm holes in the hoses where they pass over the ends of the screws.
Crossover hose due to the sharp bend in the hose, and the high pressure switch/blowoff valve.

[kings1527]

But because of it, I did get some advice: if possible, use a jack to apply just a little bit of lift to the body of the car, not the frame. This little bit of lift opens the space between the fiberglass body and the frame just enough to allow for easy insertion of the passenger's side hose. It was also suggested that I may need to loosen the bolts holding the body to the frame, but I didn't have to do that.

Anybody else have to do this?

tl;dr: Love the hoses, I recommend them. If installing, you may need to try opening the passenger's side frame/body gap slightly for easy fit.

Exactly what I had to do. Just a tad of lift from a jack applied to the fiberglass tub, maybe about 1/4", and that fixed any kind of hose hangup on the passenger's side during installation. If I had to install Hervey hoses again on my car, I could do it in probably 30 min from start to finish without rushing at all.

[Chris4099]

But because of it, I did get some advice: if possible, use a jack to apply just a little bit of lift to the body of the car, not the frame. This little bit of lift opens the space between the fiberglass body and the frame just enough to allow for easy insertion of the passenger's side hose. It was also suggested that I may need to loosen the bolts holding the body to the frame, but I didn't have to do that.

Anybody else have to do this?

There was once a thread somewhere here where a person was having issues installing John's passenger side split hose. A person recommended they lift the car by the body and not the frame and sure enough, he was then able to install the hose. When I installed my split hoses, I used a two post lift which lifts by the body and I had no issues at all. Slid right in. The frame seems to flex down just enough to give it the room it needs.

I just checked my notes and I last charged my AC system back in Dec of 2008. No recharge since! So John's hoses work great and the extra connection has been trouble free. If I were to re-due my AC system now, I would probably go with DPI's since it's a newer style hose. But with the barrier hose I have now, it should last a very long time, so I have no regrets.

I'm a big believer in replacing all hoses though, not just one if it fails. Skip NOS and go new. With all new modern hoses, you should get long life without ongoing recharges needed.

[David T]

Most common leak overall - shrader valves.
Most common damage leak - hose rubs on the steering column
Most common installer error leak - hose melts on the crossover pipe
Other common leakers - O-rings at condenser, low pressure switch.

Not as common but we've seen a few:
Evap core (usually a fast leak)
Compressor bearing;
Return hose about every 5 inches for the whole length of the hose;
Either hose when some idiot replaces the gas tank cover screws with longer screws, or leaves out all the washers. Pokes nice 8 mm holes in the hoses where they pass over the ends of the screws.
Crossover hose due to the sharp bend in the hose, and the high pressure switch/blowoff valve.

Replace the cores with better ones and use brass caps, not the plastic dust covers. Typically the leaks will start with the high side components because they are working the hardest handling the highest pressures and the hottest temperatures. That includes the discharge hose and schrader valve and the sealing "O" rings at the connections.

[DMCMW Dave]

Replace the cores with better ones and use brass caps, not the plastic dust covers..

I'll disagree with this one. I've seen too many cars where the brass caps get wrenched on so hard that they taper the opening. Then when you go to replace the shrader valves, they get stuck or, worse, break and fall into the hoses. The plastic caps will have O-rings in them and seal good enough.

[David T]

I'll disagree with this one. I've seen too many cars where the brass caps get wrenched on so hard that they taper the opening. Then when you go to replace the shrader valves, they get stuck or, worse, break and fall into the hoses. The plastic caps will have O-rings in them and seal good enough.

We can agree to disagree. The plastic caps are only to keep the valves clean, not to hold against pressure. If you aren't going to use the brass caps because some ham-handed people overtighten them, that logic can be extended to a LOT of things. If the brass caps leak you use an "O" ring or a copper flare gasket, not try to overtighten the caps. This is just one more reason only experienced A/C guys should be doing some of this stuff.

[DMCMW Dave]

We can agree to disagree. The plastic caps are only to keep the valves clean, not to hold against pressure. If you aren't going to use the brass caps because some ham-handed people overtighten them, that logic can be extended to a LOT of things. If the brass caps leak you use an "O" ring or a copper flare gasket, not try to overtighten the caps. This is just one more reason only experienced A/C guys should be doing some of this stuff.

If that was true they would not have O-rings in them. They do. BTW every modern car from the R134 era to now has plastic caps. There is nothing inherently leaky about plastic.

And - I've opened enough plastic caps to the sound of "sst" from the bad Schrader that I do know they hold pressure. At least some.

[Bitsyncmaster]

If that was true they would not have O-rings in them. They do. BTW every modern car from the R134 era to now has plastic caps. There is nothing inherently leaky about plastic.

And - I've opened enough plastic caps to the sound of "sst" from the bad Schrader that I do know they hold pressure. At least some.

I have never seen an R134a cap made of metal. Yes the plastic caps should have an o-ring in them and so do the metal R12 (R22) caps.

[DMC5180]

This brings up a good question. Are the valve cores used in A/C systems made with specific compatible materials and rated for high pressures? IE not your typical tire valve core.

[David T]

This brings up a good question. Are the valve cores used in A/C systems made with specific compatible materials and rated for high pressures? IE not your typical tire valve core.

Yes, you CANNOT use ordinary tire valve cores. They are not rated for the pressure and temperature used in A/C systems. And they do wear out and need to be replaced.