This could have been trouble...

As previously threatened, I was going to post another "how to", this one along the lines of fixing your whale's intermittent manual climate controls. My wagon came to me with this problem and I figured it was a simple case of oxidized contacts that a good shot of DeOxit cleaner would clear right up, same as the cruise control.

What I didn't take into account was the rather larger amount of current that flows through the climate controls as compared to the cruise control switches.

Of which more later.

I want to tell you all about the experience of removing the control head. This started out well enough, with removing the ash tray. Just four bolts, two per side, one per "tier" (drink holder/misc purpose tray area and the ash tray part each count as a tier) that are not really clearly identified in the service manual as to where you will find them let the assembly drop down. Be ready to support it as you remove the last bolt. To my amazement, there's enough wire going to the light and cigarette lighter plug that you can flip this assembly over and unplug the connections. The one for the cigarette lighter is particularly novel. You'll see what I mean if you have to remove it. Someone really thought this out. Unfortunately, that concludes the good news portion of our broadcast.

The previous owner of my car left behind about 10,000,000 pennies in the topmost compartment. He He, I'm RICH.

Now, with the manual climate controls, there is a rod that runs from the temperature slider to the evaporator and heater core compartment. This looks not too much unlike a throttle cable for a lawn mower. The service manual emphasizes that you must NOT take the control head out without removing a cable retainer (easy) and then pressing a tab to let the outer sheath of the cable come free. I'd like to tell you that is easy as well, but I'd be lying. So I won't. It was a royal pain in the butt. You can't actually really see what you're supposed to be pressing on as it's on top of the molded plastic that makes up the climate controls. I puttered, fiddled, dinked with and screwed around trying to get that tab and clip to release. I ended up breaking the tab, but that at least let the cable come free from the climate controls...and I didn't end up breaking it loose from the flapper in the evaporator compartment (which would have been oodles more fun to fix). I can glue the tab back on to the climate control plastic frame, no big deal (he said, whistling tunelessly).

The wiring and vacuum connectors are another sad story. The service manual implies that these should be removed from the back of the control, before you take it out. Since the connectors have locking hardware on them, this is basically frickin' impossible to actually do.

I didn't need to go quite that far to see that I had a far worse problem than I thought. See the burnt and melted plastic?


Even the wiring connector was not spared. I think it's safe to say that this could have started on fire! It certainly explains why I had no working blower fan in the defroster mode. In fact, I'm surprised that the fan ran in any mode, and that it started working better the more I exercised the slider control!


I decided at this point to actually remove the switch from the climate control module and have a closer look at it...in for a penny, in for a pound and all of that. Yum-yum.


There's definitely nothing to save there. I figure a good connector can be found with some adventures in "yarding". I'm less sure of what to do about the switch. I really hope it's still available as a service part from someone, as it doesn't look to be repairable. I broke the burnt one to get inside and reveal the damage. I'm not sure that a used one from a yard is going to be any better than what I have now, especially given time, use and the apparent unserviceability of the switch's internals.

Having run a blower fan from another GM car on my kitchen table from a lawn tractor battery, I can rightly appreciate how much current these bad boys draw. The resistor pack method of speed control doesn't help, as the same amount of power is going to be running through the dash control at every speed except possibly "high".

On a brighter note, I got a bunch of boxes on my doorstep today containing shocks and brake pads. I'm still waiting on the discs, but RockAuto got most of my order here right quick. It'll be a few weeks before I can get to all of that...

To my surprise, there is at least one replacement switch assembly out there. I'd have almost expected the climate control center to be replaced as a unit.

http://www.rockauto.com/catalog/moreinfo.php?pk=661461

Any input would be welcome, especially if there is a generally "better" replacement out there...

Since I'm not near a junkyard that is likely to have such things, would anyone here have a replacement wiring connector kicking around? Grafting a new one onto the ends of the existing wires should not be a problem.

Ah, crap. Went to order that switch tonight and it's no longer available for sale.

I guess I'm going "yarding" for both that and the connector then...

Edit: eBay's a wonderful thing!

I gotta ask: why am I talking to myself here...am I really so lucky that this kind of thing could only happen to me? Why I'd be so surprised by that I have no idea. My life is a comedy after all.

Well I hope the auto climate controls don't draw so much current that they melt like that. Glad you could find the parts you need to get it all fixed back up. Don't you just love it when a simple clean the contacts project turns into replacing all the faulty parts project?

scoffman wrote:

Well I hope the auto climate controls don't draw so much current that they melt like that. Glad you could find the parts you need to get it all fixed back up. Don't you just love it when a simple clean the contacts project turns into replacing all the faulty parts project?

The automatic climate control system is split into multiple parts. I don't know how it handles the fan speed control, only that it appears to be done with solid-state switches (as there are no audible relay clicks other than the high speed fan relay).

Before I started working on this stuff, I always thought that the automakers (speaking mainly of the "big three") did the intelligent thing and used a fan motor with multiple speed taps. Then I found out about the resistors that are placed in series with the fan motor to slow it down. This means that the electrical current going to the fan motor and through all those switches is the same (or very close to) no matter what fan speed you select. You're either sending power to the motor or wasting it as heat in those resistors.

At first I thought maybe it was probably appreciably cheaper to do it that way, what with having fewer taps, wiring going to those taps and that the motor windings could be simplified. I'm not so sure that it would make any real difference, since you have to run wiring to all the resistor coils anyway, pay someone to install the resistor pack in the air plenum and all of that good stuff.

The amount of power those stock fan motors will draw is enormous. While I had the stock blower motor and wheel out of a 1989 Buick Electra, I set it up on the kitchen table just to see how much air it blew by hooking it up to a lawn tractor battery. As the two contact points are very close to another, I fused the hot wire going to the motor, using a 20 amp fuse (IIRC) just as GM did in the car. To my surprise, the fuse and my wiring (12 gauge) both got warm! I also noticed arcing any time I connected the clip lead to the battery and it left pits in the terminal post!

Hooking this contraption up to a multimeter on its current measuring scale (and trusting my memory once again) indicated that the blower motor was drawing some ~14 amps (170 watts) running wide open! Wowee. That's a lot of current to be putting through cheap plastic switches and such.

It's also worth noting that those fans are frickin' wicked. Not only did I have a "tabletop tornado" going on, the amount of sheer torque that motor put out was duly impressive. It became clear that the ventilation system, heater core and A/C evaporator slowed the airflow considerably. Unloaded, though, this thing would effortlessly blow away papers, telephone directories, most of the napkin holder , pens and pretty much anything else that wasn't chained down or attached to an alarm system. It also did a nice job of disturbing the papers on the fridge clear across the room!

If you had occasion to do so, the blower assembly would do a nice job of removing wigs and toupess from afar. Not that I said that.

And oh yeah: I do just love it when simple projects go all complicated.

Thanks for the pics Bill and good luck finding those parts!