Thanks for doing this and sharing, it'll be searchable in the forum archives!

 

Hey guys, so I'm figuring out issues with my A/C in my Previa. I'm using this thread as a logbook for the work I'm doing and hopefully will provide some useful knowledge to someone in the future.

When I first got my previa, the guy who owned it before me rigged up a switch to force the blower motor on outside the factory wiring.

Do you know why they did that?

 

There was a relay that needed its contacts cleaned underneath the fuse panel cover. I took it apart, cleaned the contacts, and the blower fan worked once more

EDIT: see further reply. The relay wasn't the only issue.

 

Hey guys, so I'm figuring out issues with my A/C in my Previa. I'm using this thread as a logbook for the work I'm doing and hopefully will provide some useful knowledge to someone in the future.

When I first got my previa, the guy who owned it before me rigged up a switch to force the blower motor on outside the factory wiring. I undid his work and restored back to factory and got it working, but unfortunately the A/C didn't work. In the process of finding out the problem with the A/C, I dropped the switch that turns it on down the HVAC vents (I suspect).

Rather than retrieve it which I believed to be a lot of work, I've opted to replace it with a switch from a 4Runner/Tacoma. From what I've seen, there is no replacement Previa A/C switch and the button in these seems to be unique to this dash style. Can't post links since this is my first post so here is a screenshot of the Amazon listing.

View attachment 450709

I first began with reverse engineering then switch and putting it down on paper. Top and bottom pictures and then a combined image below. View attachment 450705

View attachment 450706
View attachment 450704

After this, I began analyzing the differences between the pinning of this switch and the wiring of the previa connector. I came up with the below circuit and rewiring instructions. I've yet to test this just yet as I just finished figuring all this out, but if I'm unsuccessful I'll update. Just wanted to get all this compiled information out here on the web in case I get busy and forget to ever post it.

View attachment 450708

Hey guys, so I'm figuring out issues with my A/C in my Previa. I'm using this thread as a logbook for the work I'm doing and hopefully will provide some useful knowledge to someone in the future.

When I first got my previa, the guy who owned it before me rigged up a switch to force the blower motor on outside the factory wiring. I undid his work and restored back to factory and got it working, but unfortunately the A/C didn't work. In the process of finding out the problem with the A/C, I dropped the switch that turns it on down the HVAC vents (I suspect).

Rather than retrieve it which I believed to be a lot of work, I've opted to replace it with a switch from a 4Runner/Tacoma. From what I've seen, there is no replacement Previa A/C switch and the button in these seems to be unique to this dash style. Can't post links since this is my first post so here is a screenshot of the Amazon listing.

View attachment 450709

I first began with reverse engineering then switch and putting it down on paper. Top and bottom pictures and then a combined image below. View attachment 450705

View attachment 450706
View attachment 450704

After this, I began analyzing the differences between the pinning of this switch and the wiring of the previa connector. I came up with the below circuit and rewiring instructions. I've yet to test this just yet as I just finished figuring all this out, but if I'm unsuccessful I'll update. Just wanted to get all this compiled information out here on the web in case I get busy and forget to ever post it.

View attachment 450708

Good luck, if it doesn't work out i've got 2 extra used switches from old Previa's....

 

That's awesome to hear! I'll gladly buy one off of you if I can't get this working

 

I already opened up and cleaned up the blower speed control switch. I don't remember there being a removable "intermediate harness" in mine but that could just be memory (it's been almost a year and a half) or maybe I just didn't dig deep enough.

 

I found mine pulling the entire HVAC panel out. It's right around the bend to the left the harness takes. Visible with HVAC control panel inside dash but it'd be a challenge to unplug without pulling it if you have medium to large hands. If yours doesn't have one snap a pic, I'd be interested to see.

 

I only took out the radio, not the whole HVAC so that probably explains why you saw more than I.

 

Yep. Definitely a pain pulling that HVAC panel. My recommendation is get some snap rings to free the cables. Apply some light tension on the back with your hand and then open the retaining tabs with your snap rings, there's a bit of a trick to it

 

Hey guys, new to the forum, but I happen to have purchased OtherDalfite's 92 Previa LE a few months back and have just revived its AC. I have not taken the time to look at the 4Runner switch, so am reporting on how it works as OtherDalfite wired it.

With the blower fan moving air (Any position except off), the switch works perfectly. AC on and off as you'd expect. However, if the blower fan is turned off and the AC switch is off, the AC always runs (compressor engages/engine idles up) without any blower motor running, front or rear. If the
AC switch is on with the blower fan off, the AC does not turn on, but the FR HTR relay makes a loud buzzing sound. Without really investigating the problem much, I suspect it is related to the diode in the wiring diagram above.

I think this van has a history of AC wiring issues, as the high pressure switch under the hood was unplugged when I was first trying to get the compressor to cycle on. Regardless, AC is nice, and for the time being I will just keep the blower always on low to avoid the issue.