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90 Wagonner Renix HVAC Vacuum

justfalcon

NAXJA Forum User
Location
Indiana
I haven't found a clear and concise answer for this


Not getting much coming from vents, has been that was since I got the XJ. Full cooling / ac refresh with everything replaced. Still not getting much from vents and no heat.

Relocating vacuum canister under coolant tank - but my canister has two nipples on each end with no markings. I tested the canister and it holds vacuum so that isn't the leak.

I also noticed that my 2mm vacuum lines coming from firewall under coolant tank are black and white - everything I'm reading is orange (which is under dash - vacuum motor holds vacuum and flaps move but am not getting vacuum from orange line to wherever it goes.) and pink, etc. coming out the firewall.

Neither of these lines hold vacuum - I understand only one is but since the colors seem to be different, I tested both.

Anyone have an actual vacuum diagram from the firewall to dash? Am I missing something?
 
Vac-ball-routing.jpg


AC-Vacumn.png


Heater-Vacumn.png


There is a vacuum connector on top of the heater controls, it has been known to come loose.
 
Vac-ball-routing.jpg


AC-Vacumn.png


Heater-Vacumn.png


There is a vacuum connector on top of the heater controls, it has been known to come loose.


Thanks -

Are you talking about the multi-prong vacuum connector? If so, I reconnected that and it did get a little better but it's still not working right.

So if I'm looking at this correctly, at the firewall, the black one (I've got Black/White coming out the firewall) is the vacuum?

If that's still not fixing it do I have to hunt down all the vacuum lines in the dash?
 
Additionally, from the back of the heater control - the white vacuum line is just a small U loop that goes back into the manifold/plug for the back of the heater control which doesn't seem to look like anything in the diagrams
 
There are 2 plastic tubes going through the firewall.

Pinkish one comes OUT of the firewall from the heater control to the coolant valve in the engine bay.

Other one is the vacuum source for the heater control from the vacuum reservoir.
 
So let's take a step back.

With the engine hot and the heater control on any heat setting, are both hoses to the heater core hot? (be careful touching them).

If so, then hot coolant is flowing through the core. If not, you have some blockage in the core or one of the lines, perhaps even a bad heater valve.

Next, turn the fan on high, is hot air flowing from the defrost vents? If so then the airflow seems OK. If not, you may have debris in the heater box blocking airflow. You need to remove the fan from the firewall side and reach in to remove the debris. Tread carefully as you contact the heater core if you reach in far enough.

I'm not saying your issues is not vacuum related, but you should check the other elements.
 
There are 2 plastic tubes going through the firewall.

Pinkish one comes OUT of the firewall from the heater control to the coolant valve in the engine bay.

Other one is the vacuum source for the heater control from the vacuum reservoir.


That's what I'm running into - I've got black and white coming through the firewall - I assume black is vac source and white goes to heater control valve?
 
And I'm just now getting to the vacuum/blower issue - I just finished up a full front suspension refresh.

Since my vac canister has two nipples on each end I'm just looping one of them and only using the other two (one on each side) as I'm seeing in all the diagrams.
 
Ok - I just turned the jeep on and felt the coolant lines after it got up to temp - not hot. Heater valve is brand new.

Here is my vac canister and the mess under the dash - new blower resistor.

B8T20Eo.jpg


Here's the black and white out the firewall

PXHp1hw.jpg


There's a mystery connector under the dash that's wrapped in the same harness as the blower fuse

vMApjWj.jpg


Orange - per diagram is going to vacuum motor

2RHbjrj.jpg


The nipples on each end of the canister are two different sizes, but there's zero marking on the canister indicating anything special for each or each side.

Currently I have the intake vacuum source going to one end of canister, two of the nipples are looped closed and one line out going to firewall w/ T splitting to cruise.
 
Sorry for the multiple posts - real annoying I can't edit posts.

Hot coolant is now going to core. Am getting still very very weak air coming through vents but heat is now coming through vents for the first time.

I have a new blower motor but not a new heater core but have yet to install. Blower motor speed does seem to function though it's hard to tell. I'd say what "max" is now is probably 10% so going from high to low goes from 10% to 1%
 
Pull the blower motor out to access that stuff first.

So I've replaced the heater core and ac core, reinstalled the hvac box and while it was out tested vacuum on each of the lines - no leaks and all flaps work.

I've got everything hooked up and am getting heat - still weak flow through the vents. I know it's not going to be like a brand new car but still feels weak for an XJ.

Out of the firewall, I've got the black and white, there were no check valves or anything else originally.

So -

-- From intake (source) I replaced the fitting with one with more flow and replaced the main source vacuum line to the vacuum ball.

I've capped off two of the 4 outlets in the vacuum ball. Mind you mine has absolutely no markings on it, two of the nipples are ~6mm and 2 are 2-3mm.

-- From the firewall:

Black vacuum line goes to vacuum ball.

White goes to heater control valve, which was replaced w/ new.

-- From vacuum ball

on the one main "out" that I'm using, I have a y connector so it goes

Vacuum Ball > splitter > black vacuum to firewall > splits to cruise control

Realized I have what I believe is the transfer case vacuum line left, so I unplugged one of the 6mm nipples on the ball and have that line going to that.

Idle seems to be better overall, as I was getting reallllllly low idle prior to doing the heater core.

Now - engine is overheating big time, which it never did before. Am still getting some heat through the vents and have not hooked up to pull vacuum for a/c system yet.

Am I hooking something up wrong or missing something?
 
I also keep seeing diagrams for like blower motor grounds and resistors, I appear to have none of that. Replaced the blower motor as well and how I got the Jeep, it just has a live/ground from the blower motor straight to the plug on the harness. It works but still feel like something may be missing.
 
Well, you likely have a lot of trapped air in the system since you replaced the core. You'll need to run through a few heat/cool cycles to purge the air out.

I also take the radiator return hose off the thermostat housing, hold it high and pour fresh coolant to ensure the radiator is full.
 
Update: removed temp sender while cold, ran for a little bit to get air out - put back in and am trying to bleed that way now, on a downward slope. Seems to have gotten some air out - I guess just keep cooling down and repeat?

Jeep is still running at ~240. Would doing the 92 thermostat mod help in this case?

On the ~4hr drive back where I bought it, it ran under 210 the whole time but so much other stuff was wrong that had to be addressed...
 
Well, you likely have a lot of trapped air in the system since you replaced the core. You'll need to run through a few heat/cool cycles to purge the air out.

I also take the radiator return hose off the thermostat housing, hold it high and pour fresh coolant to ensure the radiator is full.

I figured that was the case. I can keep doing that and a few more cycles of cooldown/run.

Still not 100% sure the vacuum is hooked up correctly - I am not, since I started at this again, getting anything at all from the "Heat" setting - defrost works, vent works...
 
Do the blower motor ground upgrade on my website. http://cruiser54.com/?p=211

Did you plug the 2-3mm fittings on the vac ball, or the 2-6mm ones?

Or, one of each on the same side?

Just eliminate all that vacuum crap for the front axle and remove it's vacuum source.
https://www.cherokeeforum.com/f51/free-d30-cad-bypass-91-a-38629/

How do we know your vac rezzy is any good?

Sorry I'm only really messing with this jeep on the weekends.

I'm going to avoid doing the vacuum mod for the time being until everything else is sorted out. I am going to look into moving the ground today as well.

I blocked all outlets on the rezzy and it's holding vacuum - so one would assume it's good. Though I could pull one off my bmw 535i n54 and test if it came down to it...

Here's a diagram of how I have it set up currently. I'm using the 6mm as the source, blocked off the other 6mm and am using the two 4mm as source for the rest. I am going to replace the vacuum line going to the TC because it's rotted out though that shouldn't be causing any of the HVAC issues (I don't believe)... (HC = heater control valve / TC = transfer case / CC = cruise)

I think as far as the overheating goes - it does just have a ton of air it in so I'm going to keep bleeding that today. I have not charged up any of the AC system yet though that also is holding vacuum - that shouldn't cause any issues though either, besides not getting cold.

04FJ1pfl.jpg
 
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