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.
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.
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.
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.
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.
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.
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