'90 New Yorker Hot under the Ignition Switch

Hi all!

My '90 New Yorker, 3.3L, has a problem that has me stumped. Whenever I
drive the car, and the a/c heater blower is running, the plastic cover under
the ignition switch gets very hot to the touch to the point that the plactic
has cracked. I have also had to replace the ignition switch three times in
the last three years. This car has ATC. I am thinking that either the ATC or
the blower is drawing too much current, but how can I tell which? Or could
there be some other cause?

THanks in advance for reading, and for any advice.

Dennis

sedNOSPAMMERS55atyahoo.NOSPAMMERS.com
(remove NOSPAMMERS and convert at to @)

 

I was hoping someone would have responded to this. I had a similar
problem with a 1968 Dodge Dart many years ago. When the A/C was run on
a daily basis, the A/C/heat/defroster switch would get hot and melt.
We replaced it several times. There was one time, when all of the
solder in the fuse melted and dripped on the floor. (The correct fuse
was being used.) The fuse never "blew" like they normally do. All I
can figure is that the blower must have been drawing too much current.
The problem was never solved, and the car was traded in a year later.

I wished that I would have had a way to measure the current going
through the blower. I could not imagine that the A/C compressor clutch
could have been doing it.

-Kirk Matheson

 

That is because the switch was very heavily loaded even when all the
wires and components were in perfect shape. ALL the current to operate the
blower motor and compressor clutch went through that switch. Let a couple
of adjacent clutch coil windings short together, let the blower motor draw
a little too much current, and that switch was gonna melt, every time.

Very easy. Both wires were readily accessible from the engine side of the
firewall.

How come? The 6-cylinder models had higher-current-draw coils (wound with
aluminum wire rather than copper like the 8-cylinder models had) and
even with *no* adjacent coils shorted, those clutches drew a great deal of
current.

 

Couldn't they have just used a relay? They had relays back in 68...

Ray

 

With the manufacturing techniques of the day (compare the cost of making
an existing wire one foot longer vs. replacing that one foot with a
relay and at least four terminations - terminal on the end of each of
four wires, and connecting each of those terminals either with screws or
with push-on friction connections), relays added too much expense and
complexity to the vehicle cost. Also, relays add some current draw in
addition to the load it is switching, which also was a consideration to
an already overtaxed (for the day) charging system. Today's lower
component costs (in adjusted dollars) using near slave labor and
automated mass termination methods make it feasible, and, with the total
system loads, necesary, to use servo (electro-mechanical, solid state
switching) devices rather than full current-carrying controls. Weight
may also be reduced by running much smaller control wires around the
barn, so to speak, to low-current controls and switches rather than the
full current-carrying wires along the same labyrinthine paths to much
heftier switches (or, for more weight reduction, multiplexing buses,
integrated circuits, and microprocessors).

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

I suspect that cost (both parts and added assembly time) was the reason.
The extra current draw (power consumption) of the control coil of a
relay is pretty small and I suspect probably no greater than the extra
power required to overcome the IsquaredR losses of the extra wire
required to run these loads through the switch.

Relays are the way to go, but I'm still not convinced about having the
BCC controlling the relays. There is a noticeable lag in my 03 Caravan
between changing from high to low beam and the lights actually
responding. My 96 is instantaneous from the level of human perception,
but my 03 has a noticeable lag. It is probably less than 500 ms, but
very noticeable nonetheless. I don't have a schematic for my 03, but
I'm guessing this is due to moving this control the the computer to save
some wiring.

Matt

 

Yes, so the beancounters figured.

Negligible, insignificant. This is not a consideration factor.

Nope. The charging systems in Darts and Valiants were completely adequate.

Naw, the extra cost is still there, it's just taken back out by using
bare-minimum wire gauge in the load circuits. They work OK when
everything's brand new and clean, and will tolerate juuuuuuuust enough
deterioration to get the vehicle to the point of warranty expiry.

 

I *detest* these kinds of delays, and I have found them in virtually every
BCC-equipped car I've driven since the mid 1990s. Turn the key to "Start",
turn the headlamp switch on, change the headlamp beam, turn the ignition
key to "off", hit a power window switch...and there's a brief but
perceptible delay before anything happens.

 

Likewise. I just don't see the advantage and the delay is annoying to
say the least.


Matt

 

Is there a way I can measure the current being drawn by the blower in my
Chrysler? Should I just replace the blower motor? I assume by reading the
feedback that the blower motor is the culprit here since the situation
occurs whether you're using A/C or heat.

Thanks!

 

Same way you measure the current being drawn through any circuit -- with a
properly-applied ammeter.

No, you should properly diagnose the problem. Throwing parts at the
problem is a real shot in the dark.

 

You coulda just said Chrysler was cheap.

Trust me, I'm well aware of the car companies neverending drive to save
$2 on manufacturing costs per car in exchange for serviceability
nightmares... but in their defense, $1 per device x 50 devices per car x
500,000 cars is a lot of money...

Ray

 

Boy, I'll second that! The delay in our '03 GC is significant--enough
that I'm not always sure the high beams flash when I'm using them to
signal somebody that it's okay to move into the lane in front of me.

It can and should be a much faster mechanism.

--Geoff