Splicing wires in car heater...

[Adrian Brentnall]

HI All There's a known problem with the multi-tapped resistor that provides heater blower speed control on my Pug 307sw. The resistor pack plugs into the wiring loom, and, under certain conditions or over time, one pin of the loom socket can overheat and the electrical connection is lost.

There's a replacement 'loom-end' available - socket to bare-ended wires

- and the fix is to cut off the original melted socket & splice the new loom-end onto the original wires. Parts are on order -

Trouble is - the original loom is so short that getting my conventional ratchet crimp up behind the dashboard to make a decent crimp is going to be 'challenging'. Same would go for soldering.

I was wondering about the possible alternatives...? Choc-bloc / terminal block seems a bit of a bodge in a vibration-prone automotive environment, but would the Wago 221's be up to the job - I've never used them before?

Thanks Adrian

[alan_m]

I've used

You don't strip the wire - just place two wires in the holder - use a pair of piers to press the metal part of the connectors into the wire - close the lid and lock it down.

The original branding for this type of connector was "Scotch Lock" Instructional video

[Harry Bloomfield]

Trouble is, they don't usually provide a very good low resistance connection, so the connection might generate heat.

A good soldered joint is best, followed by a properly crimped connection.

[Dan S. MacAbre]

I don't know what they're called, but how about the red/blue/yellow crimped things? I use them as a last resort when there's only room for finger tips and a crimper.

[Roger Mills]

I don't know how much current the heater blower takes, but I've used Scotch-locks extensively for connecting trailer wiring without any problems. If the blue ones are not man enough, there are also heavy duty brown ones.

[Adrian Brentnall]

Yes - thanks. I thought of them, but they're almost as awkard as getting the ratchet crimper in there... though I suppose there's a little bit more leeway in the alignment of the two cables.

[Adrian Brentnall]

Understood - I don;t want to create a new problem while solving this one!

Yes - I know that - it's just the practicality of achieving either in the limited space that's available up under the dashboard. If it was all out in the open then I'd solder / heatshrink..

There was some talk on the Pug forums about gaining more length on the end of the loom by unplugging the fan connections, I might look into that once the parts arrive.

Thanks Adrian

[Adrian Brentnall]

'Crimps' - I think? Got a box-full of those and a good ratchet crimper, just not sure I've got room to get the crimper & two hands into the space available. It's one of those, 'lying upside-down with your feet on the pedals, reaching up behind the dash' situations...

I was thinking that the Wago (if they'd do the job) would at least allow a second attempt, if one missed the first time! Thanks Adrian

[Adrian Brentnall]

There's other ('after-market') high-current wiring in the car already done with the blue Scotchlock connectors. Wouldn't imagine that the blower's taking much more than 10A or so?

Again, access for the pliers to 'crimp' the connection may be difficult. Would love to meet up with the engineer who designed / specced this horrible installation, and I'd certainly use my ratchet crimpers then!

Thanks Adrian

[Tim Watts]

20A Wagos:

32A

I'd use the latter without a second thought in a car:

1) They are suitable for stranded wire;

2) They are resistant to vibration;

3) Well shielded - the sheath goes into the connector some mm, no change of accidental shorts.

[Adrian Brentnall]

Thanks. I'd thought the 20A ones would do the job. There's 5 wires in all, so I don;t want to end up with too big a 'bundle' of connectors. Are the 32A ones bigger, physically? Thanks Adrian

[Tim Watts]

A bit - but the 2-ways are more compact than a 2 way choc block strip.

Given it's a blower plus cars can get damp, I'd over engineer and go for the 32A ones if it were me :)

[Harry Bloomfield]

If ever I come across any wiring in a car using those and there has been a problem, my first suspicion is those connectors - having come across such many times. They are very amateur, they damage the existing cable and any moisture is given a direct route to cause further damage to the copper.

Heater blowers can take a considerable current, mine can draw 30amps, so good reliable connections are essential. All cars using resistors to control the fan speed seem to have problems eventually. I'm fortunate, my own uses a PWM speed controller - much more efficient and no heat generated.

[Adrian Brentnall]

I agree! Just ordered a bunch of 2-way and 3-way connectors. Thanks! Adrian

[Dan S. MacAbre]

Ah, right, this is the 'ratchet crimper' you already mentioned. Mine isn't a ratchet type (which made me think you weren't referring to these connectors) - it's a cheaper one with a small nose that gets into tight spaces quite easily.

If you can get a choc block in there, you might try folding the stripped wires back against the sleeve first - I think that helps stop them coming undone, and prevents crushing the wire too much.

[Adrian Brentnall]

Yes - they do seem a bit 'rough'.... wouldn't be my 1st choice of connector..

PWM would be the more elegant way to go. From reading on the 'net, there's lots of people with the same problem. In this particular case - two of the 5 connections on the multi-tapped wire-wound resistor are common, and the full fan current runs in on one of them & out on the other (through the common connection), which then gets hot. The plastic mount gets soggy, so does the multi-way connector, which makes for an even worse connection etc etc. One end of my connector has just melted...

One suggestion for improvement is to make the common connection actually _in_ the wiring loom - so I bought some 2-way and 3-way Waco connections to make this possible. This way, the heavy current is handled by the loom, and not via the tiny plug connector.

Having designed this monstrosity. Pug then decided that they'd better find some way of cooling it (!) - so it fits into the airflow duct, upstream of the fan - which is why it's such a pain to access!

What fun! Adrian

[Adrian Brentnall]

Same type of jaws, just a bit more reliable (allegedly). But bulkier. While I'm at it I must re-do the crimped Lucars onto the fan itself - looks like somebody crimped those using a hampster!

I think you'll start a 'holy war' with suggestions like that! I think Wago's the way to go... Thanks Adrian

[Dan S. MacAbre]

I only mentioned it because you'd already had :-) My own choc blocks now lie pretty much unused, now that there are so many alternatives easily available (how the internet has changed things!). But I think if you prepare the wires correctly, I'd use them if I had to.

Personally, I'd probably be trying to extend what bit of wire is left by soldering some more on, then pushing rubber sleeves over the join.

[Adrian Brentnall]

Yes - 'twould be ideal. Access is the problem, don't much fancy lying on my back with my head in the footwell trying to solder just above my nose! I think Wagos will do fine.. but thanks for the comments.

Just got to wait for the bits to arrive... Could do with a working heater recently, hovering around the 12c mark at the moment here in West Cork and it's only going to get colder! Roll on summer Thanks Adrian

[tabbypurr]

If you want to guarantee failure, go for it.

NT