BimmerJeeper

For the last few months, I've been having to hit the relay or press it in harder to get the blower working. Now, it no longer works, even when I push/hit the relay. The wires and relay are really hot.

Anyone know which wires tend to get damaged, and how you replace them? Does the entire harness need to get pulled? Job for a pro?

Anyone know about the wires breaking down back there? I saw this from a Google search.

I also spoke w/ my mechanic and the issue is common in Jeep's. He said eventually the wire back there gets too hot and has to be replaced, or the circuit itself goes and the box itself (new $250, after-market $125) has to be replaced.

PatHenry

The wiring to the blower motor resistor like to melt, as does the wiring into the heater control panel in the dash.

Pull the relay and replace it with a high quality brand, clean the connection and inspect it thoroughly for damage. If you haven't replaced the blower motor itself, I'd do that too.

You might want to take a trip to your local junkyard and pull the wiring harnesses involved so you have a replacement part readily available.

XJwonders

Don't forget,
You are talking to BimmerJeeper here

PatHenry

I thought about that when I was suggesting it but figured, well, he can take the advice or leave it and if anyone else comes along in the future with a similar issue....

BimmerJeeper

No problem, I only work on my German cars.
I leave the Jeep for the pros to fix.

Just trying to get a game plan.
These are old cars and even pro mechanics don't know how to work on them anymore.
I can't just pull up to a shop and say "Fix the heat" without expecting a $1000+ repair bill.
Some refuse to work on it now. Best to give them a game plan, and directions.

There is no junkyard in my area.
And I don't know how to pull a wiring harness.

Does the entire harness need to be replaced? Just certain wires? Which one?
Cars have many wires. What's the name or part number of the wiring harness in question?

How rare is this?
Is there a video or write-up on the internet on how to repair the wires?

PatHenry

Nothing wrong with that - we gluttons for punishment that prefer to do our own work on our vehicles are a minority compared to those that do not do their own repairs.

As far as the harness, if you're taking it to professional, make sure that they do electrical diagnostic and repair if possible. You don't need to replace anything that's working within spec, but sometimes it's easier to remove a section of wiring at the endpoints rather than dealing with a repair in the middle. You need the technician at the shop to figure out where you are getting excessive resistance (it could be bad wiring or a bad component) and correct it.

Take a peek at the parts catalog for your year and see if you can find the component. That will give you a part number that you can research.

I've never heard of any problems like you're experiencing with the wiring/relay near the heater box. On my 2000 TJ, a bad blower motor did cause melting of the wiring and connector at the resistor as well as at the control panel. In that case, I just grabbed the matching connectors from the junkyard and spliced them in and replaced the components.

Where in the U.S. are you at that there are no junkyards?? Do you have a compound in a desolate region where you store your collection of vintage BMW's and lone Jeep XJ?

BimmerJeeper

Thanks for the tips.
I'll research this problem more tonight.
If I can make it a few more weeks, I can skip this repair until next December.

Diagnosis is $125/hr.
It's cheaper and faster to just replace everything that is a known culprit.

I love working on my sports cars, easy peasy, just not the Jeep.

I live in a major metro area.
Junkyards don't operate here.

BimmerJeeper

Which component am I looking for?
I thought wiring harness. Do they even sell that?
Or do you mean heater blower ?

Wait, you're saying 2 different things.

First, you said this issue is common: The wiring to the blower motor resistor like to melt, as does the wiring into the heater control panel in the dash.
Now you're saying you've never heard of this problem? I've never heard of any problems like you're experiencing with the wiring/relay near the heater box.

I don't know what a heater box is.
I never used that word.

I am confused .

PatHenry

From the picture you posted, the heater box is behind the glovebox.

The stuff that melted on me is lower (the resistor) and behind the control panel (in the center). It's a common issue where the fan draws too much power when it's old and worn.

If you just want to fire the parts cannon, then replace the blower motor with a quality brand (Mopar if possible) and that will ensure the motor isn't overloading the wires.

It could even be as simple as corrosion in the conectors. It is easy and cheap to pull the connectors apart, spray some connector cleaner in them and use a toothbrush and small file to clean up the contact points.

I would do that stuff first and see if it helps before replacing whole wiring harnesses. The harnesses may be hard to come by since most everything has been discontinued by FCA.

BimmerJeeper

You're saying the resistor is lower than the relay?
I don't think I can see below down into that little gap.
Do I access the resistor by laying on my back and looking up into the bottom of the glovebox area?

I will try to inspect the wires at the heater dial switches.
I remember I had a very hard time replace the bulb behind the HVAC control panel.
I was having major issues removing the panel since there was zero slack in the wires.
I don't recall how I got past it, but that thread was epic.

PatHenry

Hahahaha - Bimmer, most of your threads are epic!

I'm not sure exactly where the resistor mounts on a 97+ XJ, but on the TJ it was accessible in the footwell of the passenger side. The wiring melted right at the connector and blackened the wires a couple inches up. IIRC it was a pain to find a connector since the few TJ's (junkyard Wranglers are scarce) they had were mostly missing the connector already. I think I actually grabbed one off an XJ.
There are several "how-to"'s online that will show the location.

If you do make the trek outside the city to a junkyard, cut the connector as far back as you can so you can have extra wiring.
I had to get a sidemarker light socket for my 95 and it's so much easier to deal with that side (with the extra slack) the the other side which has little slack.

You can check on ebay or look in the "parting out" section of the forum - someone may be able to get you any/all the wiring stuff you want to replace. I'm guessing anything 97+ will be the same, but you can confirm with the parts catalog. xjjeeps.com is a good source or maybe cruiser54.com if you need the parts catalog.

BimmerJeeper

Thanks for your guidance, Pat.

Turn out, I had a spare relay.
I popped it in, and the heater started working again.
I love when a spare part comes in handy!!
I'll buy another spare off Ebay.

Since things get hot,
I'm going to try avoid using the heater from now on.

Maybe I will save the heater blower motor project for the next time the Jeep is in the shop

PatHenry

Anytime man - glad to hear you got it working again!