I've just replaced my blower motor and my plug at the blower switch has minor burns in the plastic which i replaced with a switch from the junkyard.

even though the blower is new, I'd like to give a try to the relays fix that i read about. at best i'll avoid a fire, and at the worst i'll have less space under the kick panel!

My understand of eletric systems is somewhat limited, so i want to make sure i wire this correctly to avoid any issue. I'm planning on wiring only the 2 highest settings, so High and Medium 2.

I made the following diagram based on the blower motor circuit, and i'd like to know if what I did makes any sense. Thank you!

(i only included 2 poles to on red relays on the right diagram, but i'm aware of the ground and power needed for it to work, just in case you wanted to point that out)

 

I don't trust any diagram that's not complete, so I can't say this is correct. You are relying on assumptions, and that's a good way to get in trouble.

 

take the relay diagram i made on the left and imagine it's in place of the red rectangles, that's what i meant. the picture was too small for me to fit all the poles in there.

here's what i mean, i find it more confusing but now it's all there

 

If it's a 90 or earlier, just upgrade the ground.

 

What curiser54 said.

I see what you're trying to do, buy why? Unnecessary IMO.
I would just replace with a new switch and call it a day.

The slightly burnt looking original switch could be from the old defective blower motor or plain old age.

 

"What curiser54 said." i don't even have a 90 or earlier so it's useless.

If you really see what i'm trying to do you would understand why.. i want to prevent any issue that might come up from the stock wiring. same goes for the headlight switch. most XJs probably go through their life without any real issue, but having my headlight switch melt and smoke coming from my dash is something that scared me (because it did happen).

I live in a place where we park in an interior garage and a car fire is that last thing i want to happen. i checked my blower switch and it's as bad as the previous headlight switch that melted. There's a lot of speculation about whether it's useful or not, at least this way the current will flow directly from the battery, which cannot hurt so other than wasting my time.

For anyone interested, I ended up testing the diagram above and it worked fine, i need to clean everything up so there's no wires hanging but now the current doesn't go through the switch.

 

Well i'm glad it all worked out ok.

If that concerned though, you could of just as easily added an inline fuse in series with wiper terminal of the blower switch. With an ammeter measure the max current draw from each switch position and choose a slow blow fuse amp rating accordingly with maybe a +20% safety factor.

 

I spent hours searching the internet for a fix to a seemingly simple problem: the stock hvac wiring sucks and burns out. Everyone else suggests replacement back to the ****ty stock wiring

Your very helpful diagram is the only upgrade to this ****ty system ive found and im excited to try it


1989 xj by the way


cheers

 

Your relay setup looks mostly correct for offloading high current from the switch. For High and Med2, you’re using the switch to trigger the relays, which then power the blower directly good. Just make sure:
- Relay coil (85/86) gets switched power from the original blower wires (Med2/High).
- Relay contacts (30/87) run fresh 12V (fused!) to the blower, bypassing the switch.
- Keep grounds solid.

Since your switch already has minor burns, this should help. Test relays before final install if the blower runs smoother on high speeds, you’re golden.

 

Got it! So ill follow the original diagram here. I think ill do all 4 wires with 4 relays just to be thorough