Rear AC Box not getting power (1 Viewer)

[helloshawnsaylor]

Hey team — did a bit of searching before posting this, so if you know of a thread to point me to, please do.

My 2000 100 Series has a rear AC box (right rear side of the back cargo area) that doesn't get power when turned on. I popped off the body panel and ran power to it directly from a battery and it spins up, so the actual fan is good. I checked all the relays and fuses in the front engine bay that seem related to the AC system (but that doesn't mean I missed something). The third-row control panel for the rear air works when you control the heat, and acts like it's working/lit up when you set it to cold air, but the rear fan just doesn't click on.

Anyone here have thoughts on what else I can check?

 

[helloshawnsaylor]

Wanted to bump this, anyone have any ideas?

 

[Trunk Monkey]

Fuses and relays for the system maybe.

 

[helloshawnsaylor]

Fuses and relays for the system maybe.

Thanks @Trunk Monkey — I tested them and swapped them around and they all seem to work, but maybe I should just replace them and see what that gets me. I'll try that but if anything else comes to mind for you all, let me know.

 

[creakycruiser]

What’s the voltage on the fan leads when you try turning it on normally? 0v?

 

[helloshawnsaylor]

What’s the voltage on the fan leads when you try turning it on normally? 0v?

I'll test it when I get home and report back!

 

[helloshawnsaylor]

I'll test it when I get home and report back!

Sorry for the delay, we were traveling over the weekend.

Check out the two ports circled below, that each have 4 connections. None of these seem to have any voltage at all (testing with multimeter) when the car should be sending power to them, to power, the rear AC. If I use an independent power source and run power to the plugs (circled in the same photo) then the fan kicks on, which leads me to believe that power should be coming to these ports and isn’t.

I didn’t circle the exact connections, but I did test the exact ones that correspond with the connections on the plugs that power the fan I got from a YouTube video - but he was using a Sequoia, for what it’s worth.

Any ideas?

 

[Rebus Knebus]

You said you checked the engine bay fuses, how about the passenger footwell? At least on my 2003 there's a 30A RR A/C fuse there that's for the blower motor. If there's power there and the fuse is good then there's nothing but wiring from there to the rear A/C relay mounted on top of the A/C unit and shown in your pic.

 

[helloshawnsaylor]

You said you checked the engine bay fuses, how about the passenger footwell? At least on my 2003 there's a 30A RR A/C fuse there that's for the blower motor. If there's power there and the fuse is good then there's nothing but wiring from there to the rear A/C relay mounted on top of the A/C unit and shown in your pic.

I checked but I’ll do it again and report back!

 

[helloshawnsaylor]

I checked but I’ll do it again and report back!

So far none of the fuses seem bad, I pulled each one from the driver footbay land eyeballed them

I’ll check again today just to see if missed one but can anyone think of anything else to check short of just replacing the box in the back? What confuses me is that the ports were power should be be coming in are built into the box anyway, maybe something is off in there.

I guess I could pull the box and test the wires that go into it to see if power is making it from further up the chain?

 

[Rebus Knebus]

So far none of the fuses seem bad, I pulled each one from the driver footbay land eyeballed them

I’ll check again today just to see if missed one but can anyone think of anything else to check short of just replacing the box in the back? What confuses me is that the ports were power should be be coming in are built into the box anyway, maybe something is off in there.

I guess I could pull the box and test the wires that go into it to see if power is making it from further up the chain?

Do yourself a favor and download the 2000 EWD from the ih8mud resources page so you can troubleshoot better. Page 26 shows the location of the RR A/C fuse. Use your meter to check for 12V at that fuse. Then you'll know if it's upstream or downstream of the junction block. If you have 12V there, then look at page 254 and you'll see that there's a light green wire that takes power from there to the rear A/C relay that you can see in your picture. Check for 12V on that wire at the relay connector, no voltage and it's the wiring from the junction block; otherwise keep following downstream

 

[helloshawnsaylor]

Do yourself a favor and download the 2000 EWD from the ih8mud resources page so you can troubleshoot better. Page 26 shows the location of the RR A/C fuse. Use your meter to check for 12V at that fuse. Then you'll know if it's upstream or downstream of the junction block. If you have 12V there, then look at page 254 and you'll see that there's a light green wire that takes power from there to the rear A/C relay that you can see in your picture. Check for 12V on that wire at the relay connector, no voltage and it's the wiring from the junction block; otherwise keep following downstream

Perfect, I'll try this and follow up!