Help! HVAC - no fan, auto stopped working

[LLTB]

Hi guys, I’ve been searching here trying to find a solution to this strange problem.

I swapped the stereo and now the HVAC controls have gone dead - the fan does not come on at all no matter what buttons I push and the “AUTO” button will not light up. The buttons all “click” when pressed except for the AUTO button. It will not “click”.

Truck otherwise is running normally.



I’ve removed the HVAC panel a couple of times to see if the cables are all correctly plugged in. They appear to be.

I also checked that the toggle on the back is set to auto. It was set to “M” so I moved it to “A”, assuming that I must have moved it to M by accident during the stereo install.

The temp sensor appears to be connected.

I also removed and visually checked each of the spade fuses in the left knee fuse panel and the engine bay fuse panel on the drivers side.

Could this all be related to some relay or the fusible link? I see that mentioned in other threads. How can I tell if the fusible link has gone bad? Is there a visual tell?

On a related note, the stereo works great. LOL

 

[LLTB]

Well… I’ve searched the crap out of this forum and tried several things with no luck. Today randomly while driving the fan came in for 1 second and then went off.

So I’m thinking it’s a short of some kind.

Then it rained today HARD and I noticed this on the passenger front floor - it’s SOAKING WET.

I had a new windshield installed last week - maybe that’s causing this leak..

And maybe the leak is ruining some HVAC thing.

 

[retlaw]

Check the inside corners of the glass. If the drivers side is wet it may be getting into the Auto AC amplifier (white box above right knee behind dash).
The Auto AC amp can be removed, cleaned and dried out. Drill a hole on the bottom of the white box to drain future water ingress.

 

[LLTB]

I don’t think it was the water. I didn’t have any water in the truck when the problems started.

Cleaned the sunroof drains.

Going to pull the whitish colored module thingy above the gas pedal now.

 

[LLTB]

Check the inside corners of the glass. If the drivers side is wet it may be getting into the Auto AC amplifier (white box above right knee behind dash).
The Auto AC amp can be removed, cleaned and dried out. Drill a hole on the bottom of the white box to drain future water ingress.

Im going to pull that now. I’ll drill a hole. Great tip.

 

[LLTB]

Pulled the white control thingy. Looks normal?

There is a small amount of oxidation where my finger is pointing. Otherwise it looks fine. Soldered joints look good.

 

[LLTB]

Just pulled the “AC Amp” from behind the glovebox. Took it apart. No signs of water or damage. No oxidation.

Where is the relay for this system?

 

[LLTB]

Can anyone help me locate the “blower speed control relay” as mentioned in this photo? I see it’s roughly behind the glove box but I can’t find it. What does it look like?

Also, another thread mentions a relay in the driver's kick panel. What does that relay look like?

My 80 is a 97 CE.

 

[LLTB]

There's got to be a relay somewhere - I don't have an FSM. I searched on here trying to find a link to an FSM - it's mentioned in several posts but I can't find the link to actually download it.

Can anyone point me to an FSM or help me identify which relays are for the Climate Control and where they're located on a 97 CE? I do not have any blown fuses.

 

[Brindleboxer]

Here is a link to the Resources section and page for the 80 series, https://forum.ih8mud.com/resources/categories/80-series.20/. You will want the FSM and the EWD, they are good to have access to. There is a guide on YouTube, , for taking apart the HVAC control panel that may help.

 

[LLTB]

Here is a link to the Resources section and page for the 80 series, https://forum.ih8mud.com/resources/categories/80-series.20/. You will want the FSM and the EWD, they are good to have access to. There is a guide on YouTube, , for taking apart the HVAC control panel that may help.

THANK YOU- - I'll bookmark this!

 

[LLTB]

Something happened!

I was sitting, sweating my ass off with no circulation, in a parking lot with the engine running. I was responding to some emails on my phone… then I heard a faint click near my knees and at the same time my A/C came on full blast for like 8 seconds and then went off. But it was a glorious 8 seconds! I felt a powerful arctic breeze (polar vortex?) and I swear that I heard a chorus of angels! I waited, hoping it would happen again, and it did - another faint click, like the sound a relay makes, and then it came on for 2-3 seconds. After that, darkness and despair.

I put my head down by the pedals hoping I would hear it again and finally see where the click was coming from so I could identify the relay for possible replacement, but it didn’t happen again.

I think I probably need to replace that relay, I just need to identify and locate it. I’m going to look through the FSM and see if I can find a diagram noting any climate control relay in that area.

 

[LLTB]

OK, I pulled the MAIN HEATER RELAY, located in Relay Block 1 in the driver kick panel. In the FSM, it says to test certain terminals for continuity:

With my multimeter set to audible continuity test, I tested the relay:

Continuity between 2 - 4 PASS
Continuity between 3 - 5 FAIL
Apply Battery + power to 3 - 5 and test Continuity between 1 - 2 PASS

I used a 9V battery with alligator clips to energize the relay. I could reliably hear a "click" from the relay every time I tried to energize it.

Doesn't my relay fail simply because it fails continuity for 3 - 5 (2nd test)

Thanks in advance!

 

[Malleus]

yes

 

[LLTB]

yes

All right. I ordered the part from my local dealer. It’ll be here on Tuesday and then I will install it and go to the next step. $26

 

[LXDOC]

I hope you don’t have a windshield water leak. A/C System Amplifier can act like a rain gauge and catch water. Your fan will do exactly what’s you have reported. Been there. Mine occurred once after a windshield replacement and a second time when tint installers were a little lax when placing ceramic tint on windshield.

 

[LLTB]

Even without the main relay installed the climate control buttons are acting up

I hope you don’t have a windshield water leak. A/C System Amplifier can act like a rain gauge and catch water. Your fan will do exactly what’s you have reported. Been there. Mine occurred once after a windshield replacement and a second time when tint installers were a little lax when placing ceramic tint on windshield.

Well, coincidentally I had the windshield replaced AND ceramic tint on the windshield in the past 2 weeks. I also had a water leak INSIDE the cabin on the front passenger floor. I determined that to be from a clogged passenger sunroof drain, which I think I have fixed.

Regardless, the relay tested bad, so that does need replacing.

But I did remove the white A/C box that is above the gas pedal and inspected it - it seems to be okay... There were no signs of water that I could see. But I did drill a hole in the bottom of it just in case.

I will probably end up testing every single part of this system before I get it fixed!

 

[LLTB]

I got a replacement relay from the dealer and installed it.

I was still having problems, so I pulled the A/C Heater Control Assy out and tested it according to the 97 Repair Manual (RM510U) pages AC-93 through AC-96. It failed multiple tests.

So I'm on the hunt for a new old stock or known good used control assembly. I believe either "55900-60470" OR "55900-60020" part numbers will have the "AUTO" button like mine and be a workable replacement. They're both discontinued, and Toyota parts deals and Amayama don't have anything.

I could try eBay, but there's no guarantee a used unit from an ebayer ($250!!) will be any better...

Does anyone here on the forum dabble in selling parts like this?

 

[LLTB]

does anyone know if I can replace my 55900-60020 with a 55900-60010 ??

 

[Malleus]

Yes, they're interchangeable. Try @slow95z

You might also try @Engineer8000; he might be able to fix your unit.