102A3 A/C Malfunction

[jap42]

I am having a new issue, my A/C worked great when I got the bus a few weeks ago. Now as soon as I turn the A/C on the Malfuncton light comes on. Both blower fans turn on but the compressor will not start. I put my gauge on to verify there was pressure and enough to satisfy the low pressure switch. I have tried to test the switches but I can not get the connectors off them. I checked the circuit breaker in the engine compartment. there is power. Looking at the wiring diagram it looks like there is not much to it. Power flows through the Low and High pressure switches to the clutch. Is there anything obvious I am missing?

On a side note, how do these circuit breakers work? Will the pop out? Do they reset at all or are they more like a fuse? These are slightly before my time!

[jap42]

Found it! butt connector at the sensors was stressed by the zip tie holding it. The wire got cut off.

[Jim Eh.]

Good time for a solder joint?

[jap42]

Uh oh, your one of those guys lol.

I hate solder joints. They are great if you have 100% copper. But there is no 100% copper wire in automotive. Its all Aluminum or Copper coated Aluminum . The heat just stresses the Aluminum wire and makes it brittle.

The cheap vinyl coated but connectors at your hardware store or auto parts store suck to. Un-insulated steel tubes, no stops so you can overlap the wire and 2 folded crimps at least 1mm from the end and heat shrink is the only way!

Ok maybe not the only way. Solder connections, if your good at it and have the room, preform well. But a good tube splice works as well and can be done in tight quarters safely.

[Jim Blackwood]

I understand the truckers have a new type of wire splice that came out in the last decade sometime. Supposed to be resistant to liquid de-icers,

Jim

[jap42]

You can get 304 SS splices which will hold up well to calcium, but unless you find SS wire there is still a problem. Since you have to coat the connector somehow anyway to prevent shorts, I stick with regular steel and use adhesive lined heat shrink.

[Jim Blackwood]

Got news for you, those splices are tin coated copper.

[jap42]

Cheaper Stainless ones are regular steel coated in stainless (Tinned) the better ones are actually a rolled piece of Stainless sheet metal.

You can get tinned copper but those are very expensive. Usually use those for battery cables or anything larger then 8Ga. I like the ones with a solder pellet in the middle. You push the wires into the pellet and apply heat. When the pellet melts the wires come together. Then you crimp. Makes a great electrical and mechanical connection.

The cheap ones from the hardware store are aluminum. Those Suck.

[chessie4905]

All the ones Ive ever seen and used are tinned copper. Some of the cheaper ones have thin eyelets.

[Jim Blackwood]

I don't know where you are getting your splices but I've used them for 50 years and I have NEVER seen a common splice made out of stainless. I think you've been working in a specialty industry or maybe you need to learn how to identify your metals? Quite a few things you have said about splices and also wire are questionable. From my experience, almost all automotive wiring is copper, usually finely stranded, and sometimes tinned which means the strands are individually plated with tin (Sn). High temperature wire such as might be used for fire alarm systems might be stainless but that has higher resistance per foot, is much stiffer and is harder to work with. Commonly available as shielded teflon insulated sensor wire having 2 or more conductors for instance. I've seen little aluminum wire that wasn't used in power transmission, motor windings, or for high voltage/frequency applications where the core is plated with copper because of it's lower resistance. (At high voltages and or frequencies most current transmission occurs at the surface of the wire rather than the core, so a copper clad steel wire is useful for it's higher tensile strength while still maintaining near the same current capacity. Used in high voltage transmission lines.)

Also, straight aluminum wire is almost impossible to get solder to stick to without special methods because it forms an oxide layer immediately on exposure to air. It essentially has to be soldered in an inert atmosphere using a special flux to remove the oxide. Copper by contrast has an affinity for tin, lead and zinc and is easily "tinned".

Finally, the strength of stainless as a material is almost an order of magnitude greater than copper, so a perfectly usable copper splice (tinned of course) made from stainless would be very difficult to crush with the typical hand crimpers. I think you might want to either explain your statements or reconsider them.

Jim

[jap42]

Stainless splices and wire are defiantly specialty, Typically used on exposed wire in high corrosive environments or food prep. I have some from a few old projects and they work nicely, but they are very stiff and kind of springy. And yes, anything over 12 GA you need a anvil crimper. I used a hydraulic one to make connections in a gas chamber for a corrosive compounds study.

Most OEM is pure copper in automotive. But aftermarket is another story, tinned aluminum unless your paying big bucks. Sometimes not even tinned. Its not necessarily bad wire, but I would prefer pure copper.

Fire alarms rarely use anything beyond stranded copper in shielded pairs. I installed those for a short time.

This all started because you mentioned some splices that would resist liquid deicers. I assume you mean Calcium suspended in water which is becoming popular. Stainless Steel is the only thing I am aware of that would resist corroding in that environment that is readily available, at least that I could find when we did that study. This was after we melted about 200 feet of wire insulation and shorted the whole building out.

[Jim Blackwood]

Thanks for the clarification, that's good info to have and no doubt also enhances your credibility here.

Jim