blower speed and air conditioning switch

[Jonny]

AC not working. Not sure where to start.

Symptoms...
Front blower works on all settings, but M2 setting blows at Low speed. (Repair manual definition of speeds is Low, Medium1, Medium2, and High).
AC switch does not work, button light does not illuminate and no evidence at all of any AC system function.

Are these two things related? I read elsewhere on the site that the blower switch influences the AC switch but it was not specific and the wiring diagram in the repair manual is too complex for me to fathom. It sounds like a major expedition into the dash to investigate the front blower switch so I was looking for an opinion or two before embarking.....

jonny

[tbkilb01]

http://Youtu.be/eIV5nWOeMpA

The Front blower switch is a challange the 1st time, becomes quite simple to remove afterwards...Once you remove cupholder its down hill. Theres a youtube vid on that part. Pay close attention how the assembly actually works its wAy out of the dash console/compartment because it only goes in that exact particular wAy.(just in reverse) If not, believe me it becomes a virtual impossible feat, your worst nightmare kinda thing, especially in the position your body has to be in(twisted). Might be easier if the seats were removed? The cupholder unit will only go back in a that exact/certain angle! Cigarette lighter outlet, and hidden door beneath ash tray also need to be removed(quite simple). Pull knobs off switches and lift up fuse box cover. Then you can see a few more screws holding in center console vents/switch cover. You gain access to switches from there. A couple of screws hold the assembly in place. (Top and bottom). Same As if you wanted to remove the radio. A couple of screws hold switch in. From there you can run your tests across switch wires/A/C button to check resistance, current or ohms or whatever? It Might be easiest to go to upullit and grab the switches to try(assumming they work). And gain practice so not to hurt your dash. Did you check A/c relay/fuses? Run any electrical tests yet?...
Screws behind air vents are tricky, but surely patience will prevail. I ran through yard previas and found it takes about 20 minutes to get to that point and less than that to assemble. Hardest part is cupholder removal and install. Word of warning, watch your air vents! The parts are super fragile! Broke mine that wAy and they were working fine. And Havent found good replacements yet...

[Jonny]

I've not done anything yet.
I did finally find the part of the manual where the instructions are for testing the switches. For the front blower switch it looks like the Low position needs continuity on terminal 5 and 6 while the M2 needs continuity on 2, 5 and 6, so I'm pretty sure I'm simply not getting a connection on terminal 2 and thus both positions of the switch are finding the Low speed.
So disassembly begins. I'll fix the blower switch and see if it has any effect on the AC function.

[tbkilb01]

So you have shop manual?

[Jonny]

Yes. However I'm not very confident with diagnosing electrical stuff and a second opinion from someone who has been there is very helpful. Your post above was great since the manual is sometimes only good for so much.
Terminal two of the blower switch was totally toasted.
AC switch simply pulls out forwards, which is nice. Continuity was not as it should be.
Two independent switch problems, I think.
I took some photos so I can post them to help other first timers (finding those last screws was quite frustrating) but I have to do that from a friend's computer so it'll be a few days.
jw

Edit. In retrospect, since my blower was still fairly functional - only missing one speed - and since the replacement of components is such a hassle, I should have waited until the blower was more seriously compromised before replacing the switch. If you determine that the switch is the problem and you want to fix it, it might be worth spending the extra money for a new one if it's still available.... the one I got from the scrap yard was also burned badly, but since it was burned on a different terminal (terminal one) I was able to use parts of both to make one decent one. Still, a royal PITA, so beware the scrap yard for this component.
It seems like Toyota knows these switches are bad. There is a connecter between the main wiring harness and the switch connector proper which seems to serve no other purpose than to be a sacrificial burn point so that the end of the main wiring harness doesn't get damaged by switch failure. Almost certainly you will need to get this part in addition to the switch.

[TheMAN]

These era of Toyotas are notorious for crappy blower motor switches... happened to our Corolla too, the resistor was perfectly fine (did you check yours yet?)

That pigtail harness can only be easily disconnected with the gauge cluster removed




a "new" switch and sanding down the contacts to get clean copper and then adding dielectric grease makes it good as new

[Jonny]

To disassemble the central dash start by opening the bottom storage compartment and pushing in firmly on the sides to release the rubber bumper on each side seen in the photo. Leave it hanging or take it off to avoid accidentally damaging it.
DSCN2564.jpg


Remove the ash tray... this exposes a screw for the next step.
DSCN2565.jpg


Apparently the sliding cup holder tray can be removed by simply pulling firmly on it while rocking it left and right. Do it. I didn't and was continually worried about breaking the damn thing in the upcoming wrestling match. Remove four screws for the cup holder unit. One is hidden under the bottom of the cigarette lighter. Wriggling this unit out is the crux of the whole event. Basically it goes down and back, approximately parallel to the plane of the four mounting screws. What a pain. All this is simply to get to the screws on the bottom of the radio so you can get that out!
I think the Toyota engineers have meetings to discuss how to inflict the most inconvenience on home mechanics. There is much evil laughter during these meetings. 1 or 2 extra mm of clearance would have been so nice.
DSCN2562.jpg


Now remove the top cover exposing the fuses and speakers.

OK so I forgot to take a pic of the radio coming out. There are two gold screws/bolts under the front of the radio and two black screws up near the fuses. One of the following pics shows the holes where these black screws used to be. The radio then pulls out forwards. Be careful with the air vents - they come out with the radio and are a little delicate. Disconnect electrical connectors and antenna.


Here's the heater levers etc. Pull the knobs off the levers. Unclip the plastic thing with the colors on it - 2 tabs each side and one underneath. Unclip the big light diffuser - tab on the right side. Unscrew 3 gold screws. If you're after the AC switch it just pulls out from the front.
DSCN2554.jpg


If you're after the fan switch, before you go any further reach in and locate the connector shown. It is easiest to disconnect it at this point.
DSCN2560.jpg


Push the whole unit down into the space where the radio was so you can access the single screw holding the fan switch. This hidden screw which gave me fits to find is in this photo, at the back of the cavity. A stubby phillips does the job.
DSCN2557.jpg


None of the other screws or any of the vent control wires need to be removed to get at the fan switch, but if you're intent on further disassembly there are a couple of other gold screws, one of which is hidden under this connector.
DSCN2556.jpg


Now the rear heat lever can come off exposing the fan switch. Disconnect the pigtail, find the flexible tab which holds the switch in place, remove the two green bulbs, disconnect the bulb holders from the dash (upper one compresses to disconnect, lower one rotates) and remove offending switch.
DSCN2558.jpg


Either buy new parts or clean up the old ones. The female connector on mine was buried in melted plastic.
I'm assuming the connector burned because the connection was loose and sparked a bunch. So before reassembly it might be a good idea to crush the female connectors slightly to make sure they really have a good contact.
DSCN2561.jpg

Upon reassembly I chose to not install the two screws on the bottom of the radio. This way the radio can come out without having to fight with the cup holder and all the other lower dash work. Remove two screws and out comes the radio. That's it. Sooooo much better. The lower section of the radio clicked into place and seemed quite secure.

Thanks TheMan for the detailed photos of the switch itself in the previous post.

[timsrv]

http://www.toyotavantech.com/forum/s...sh-on-a-Previa