XJ Assistance?

"Steve is equipped with Electronic Fool Injection" (itsalwayssteve)
05/20/2018 at 17:30 • Filed to: XJ Cherokee, Air conditioning

Doing a little maintenance on Cheapster Cherokee and saw this guy unattached to anything:

just hanging down between the washer fluid and coolant bottles. The line goes into the dash

So should it be plugged in somewhere? The only place I saw that could be proper is this vacuum canister with a large opening plugged up either with a plug or RTV sealant.

Also noticed that someone put the wrong AC hoses on this vehicle at some point in its life. Note the worn down spot on the underside of the hood:

The ac compressor clutch isn’t engaging so no air. Also it only blows through the defrost vents at the top. Since the mix doors are vacuum-powered and that line goes into the dash, I think it might be the issue.

DISCUSSION (23)

Tristan > Steve is equipped with Electronic Fool Injection
05/20/2018 at 17:46

Yes, the only vacuum line that goes into the passenger compartment is the one that controls the HVAC. They’re notorious for falling off. The cannister you pictured is the charcoal canister. I would have to go look at mine to see if yours is hooked up properly, but the HVAC vacuum doesn’t go there. You should have a vacuum port on your intake manifold near where that line reaches that isn’t hooked up to anything.

And the hood rub- just accept it as build quality that comes from a failing company bought out by another failing company (AMC->Chrysler).

gogmorgo - rowing gears in a Grand Cherokee > Steve is equipped with Electronic Fool Injection
05/20/2018 at 17:59

99.9% that’ll be the vent selector issue right there.

If we’re talking early ‘90's XJ here, it looks to me like you’re confusing a/c hoses with heater hoses? There’s a vaccuum operated valve in the heater line from the factory that controls coolant flow through the heater core. It likes to seize up if doesn’t move very often, so it’s pretty common (and universally recommended) to remove it. There’s zero negative consequence to this because the air temperature is controlled by a blend door, not coolant flow, and having constant flow through the core with the valve removed will prevent crap from clogging it up. But you also need to plug the vacuum line that went to it or else you loose all vacuum pressure to the heat controls. Plug that vac line and see what happens... There’s a chance it’ll fix your a/c compressor engagement issue too.

That “vaccuum canister” is your charcoal canister, part of the evap system. The actual vaccuum canister is in the passenger corner of the front bumper. Pretty common for it to get pulled with the bumper and not hooked back up properly, which is another common issue that’ll lead to vents not selecting.

What photos do you need? I’ve got an XJ in the garage that all that stuff’s still hooked up on, and the MJ in the driveway that’s missing the heater valve.

gogmorgo - rowing gears in a Grand Cherokee > Tristan
05/20/2018 at 18:07

There are two vacuum lines going through the firewall. One feeding the HVAC and the other coming back into the engine bay controlling the heater flow valve.

Tristan > gogmorgo - rowing gears in a Grand Cherokee
05/20/2018 at 18:09

I believe the heater flow valve went the way of the dodo after about ‘94... I know my ‘95 didn’t have one and I think Steve’s is a ‘96.

Steve is equipped with Electronic Fool Injection > Tristan
05/20/2018 at 18:11

Mine’s a 94. Heater blend is fine.

gogmorgo - rowing gears in a Grand Cherokee > Tristan
05/20/2018 at 18:12

Pretty sure they went away for the ‘97 refresh. Although they tend to go AWOL on most XJ’s anyway because they’re completely unnecessary.

Either way, the heater valve has that 90° elbow on it. I don’t remember any others.

Tristan > Steve is equipped with Electronic Fool Injection
05/20/2018 at 18:12

Does it have a flow valve?

gogmorgo - rowing gears in a Grand Cherokee > Steve is equipped with Electronic Fool Injection
05/20/2018 at 18:18

Heater blend is irrelevant to the heater valve. The temperature selector blends cold air from outside(via the a/c evaporator if equipped) with air that went through the heater core. The only way it would be affected is if the heater valve was seized, then you’d have cold air blending with air heated by whatever trickle of coolant was making it through the valve.

If your heater hoses run from the engine to the firewall without interruptions, the heater valve’s gone AWOL. Plug that loose vacuum line, see what happens.

Tristan > gogmorgo - rowing gears in a Grand Cherokee
05/20/2018 at 18:18

‘94-’97 are all weird years, tbh. I know my ‘95 didn’t have a flow valve, but a ‘93 I spent a lot of time under the hood of did. My ‘97 has a lot of one-year-only stuff on it. For instance, it’s the only post-refresh year that still had a stand alone TCU for the AW4, yet it’s completely different from any of the previous years’ TCUs, and it uses the ‘97+ CANBUS to communicate with the one-year-only ECU.

gogmorgo - rowing gears in a Grand Cherokee > Tristan
05/20/2018 at 18:28

Interchange on the valve is ‘91-’96. The HVAC controls didn’t change until ‘97 for the entire production run, the valve changed in ‘91 corresponding to the change from closed to open cooling post-Renix.

Most of the heater valves went AWOL because they caused problems and were unnecessary to the proper function of the heater. I’m more inclined to believe that had already happened to yours before you got it than that it left the factory that way, unless you bought it new.

Tristan > gogmorgo - rowing gears in a Grand Cherokee
05/20/2018 at 18:31

It’s possible... I bought it in 2002 with about 100k miles, so it wasn’t terribly old.

gogmorgo - rowing gears in a Grand Cherokee > Tristan
05/20/2018 at 18:43

No guarantees it actually went bad either. I seem to recall reading about a TSB suggesting they were removed to maintain flow through the heater core to prevent it from clogging. But when you buy a used vehicle you never really know. That’s not super old but it’s still 7 years.

Tristan > gogmorgo - rowing gears in a Grand Cherokee
05/20/2018 at 18:49

I remember thinking when I bought it “wow- this thing is so new!” lol. Even 16 years ago my cheapassery showed. It was 7 years young and a one-owner car... with a branded title and front end damage!

Steve is equipped with Electronic Fool Injection > gogmorgo - rowing gears in a Grand Cherokee
05/20/2018 at 20:09

The hose that rubs against the hood is definitely an A/C hose. It’s connected directly to the compressor.

gogmorgo - rowing gears in a Grand Cherokee > Steve is equipped with Electronic Fool Injection
05/20/2018 at 21:54

Went out, took some photos.

This is how a PO plugged the line that would’ve got to the MJ’s heater valve, which is gone. I suspect the greasiness on my a/c evap block thing is why the a/c has stopped working so effectively. Damn, that’s going to be a bugger to fix.

Kinja'd!!!

You can also see the charcoal can under it, with nothing connected to the same port you have blocked. I didn’t know there was anything amiss here until I compared it to my XJ. One other thing you can see is the two vacuum lines coming out of the firewall, one going into the main vac harness and the other to the elbow.

This is the miraculously functional (or seized open, same diff) heater flow valve on my XJ:

Kinja'd!!!

You can see the attached vaccuum elbow on it.

And this is the charcoal canister on the XJ:

Kinja'd!!!

You can see the thicker vacuum sorta hose on that nub there. It runs up along the firewall, over the valve cover (you can follow it a bit in the second photo), and hooks up to a hard line here:

Kinja'd!!!

This is on the firewall just the other side of the engine, near the intake. You can see the chunkier section of wiring loom that goes through a big geomet in the firewall just behind the red line. The red line follows the hardline, I didn’t bother tracing the other end of it. The arrow points to where the rubber hose coming off the charcoal canister goes onto the hard line.

Another common point of failure for the vacuum line to the reservoir in the bumper is right next to the battery. Seems it tends to get crushed during battery R&R. My XJ’s was broken there, I repaired it by slipping some double-wall heat-shrink tubing over it. It worked alright.

gogmorgo - rowing gears in a Grand Cherokee > Tristan
05/20/2018 at 22:41

The newest vehicle I’ve ever bought was 13 years old... And it looked like this:

Kinja'd!!!

I pulled the rear axle and scrapped the poor 4-banger KJ with only 77000km. I haven’t ended up doing anything with the axle yet. It was going to go into the MJ build that keeps getting put off but then I picked up a 4:10 geared factory MJ AMC 20, which I think I’ll be going with instead.

Tristan > gogmorgo - rowing gears in a Grand Cherokee
05/20/2018 at 23:02

I went through a brief spell of buying newer vehicles complete with payments. I had an ‘07 F-150 in 2010 and a 2009 Focus in 2011. The F-150 was okay until the 5.4 3v fouled its plugs, and the Focus was a shitbox. Everything about it reminded me of a series of poor choices I made that put me in that awful penalty box. I’m much happier in old stuff.

gogmorgo - rowing gears in a Grand Cherokee > Tristan
05/21/2018 at 00:04

Yeah I’d be happy going back to older stuff too if I’d made the mistake of buying not one but two fords...

Tristan > gogmorgo - rowing gears in a Grand Cherokee
05/21/2018 at 00:14

As a lifelong Ford guy, I’m offended.

[looks at driveway, sees a Chevy, a Toyota, a Studebaker and a Jeep]

On second thought... You might have a point.

Steve is equipped with Electronic Fool Injection > gogmorgo - rowing gears in a Grand Cherokee
05/22/2018 at 18:38

Kinja'd!!!