'91 Subaru Loyale Heater Contol

[Keep it in the Family]

Hello All:

 

I have a '91 Loyale that the heater blend door sticks in the vent position. Sometimes after running for a while and generally above 2000 rpm, it will switch to heater or defrost with appropriate button selected. I can hear a vacuum leak somewhere but was wondering if anyone knows where the vacuum lines are and what I would need to disassemble to get to them. I can't find any diagrams or component locations in the database I have access to.

 

Thanks 

[DaveT]

A hand powered vacuum test pump from a car parts store would help a lot.  Makes it a lot easier to test individual parts, etc.

 

Check the vacuum reservoir under the hood.

There should be a check valve in the line between the manifold and the reservoir.

 

A line runs from that reservoir to the buttons.  From the buttons lines go to the actuators.

 

The heater blend door is operated by a mechanical cable .  It only changes the air flow through the heater core or around it.

 

There is a vacuum actuator that selects fresh air or circulate air.  It is roughly behind the glove box.

It's a bit of a pain to get at the control buttons.  Remove the plastic piece that goes around them and the combination meter, and the AC vents.  There are wires, cables and vacuum lines all connecting to that button assembly.

[firehawk618]

Basically if you pull off the bezel surrounding the controls and both lower dash panels you can see where they all go and do simple tests on them.

If it were me I would un plug each hose at the controls one at a time.  Either use a vacuum pump on them to see if they hold vacuum or just suck on them with your mouth.

There's only 4 or 5 of them behind the controls.  All but one have numbers on them that correspond with where the plug in.  

The one without a number plugs into the port without a number.

Not very difficult.

The hardest part of the whole deal is getting the bezel back on properly and centering the heater controls up.

[firehawk618]

DaveT submitted his reply :10 seconds before I did lol.  Yes what he said however you indicated you can hear the hissing inside the car so that leads me to believe a disconnected or broken line inside the car.

Edited March 5, 2016 by firehawk618

[Keep it in the Family]

Wonderful. Thank you both.

 

I will check this afternoon when I get off work. If I am correct, the check valve between the manifold and reservoir should hold a complete vacuum which I will check just to be sure. Removing the bezel and testing the lines is what I was thinking, but thought it best to ask; don't need any extra headache.

 

I'll post my findings

[TomRhere]

After much searching around the components, I found my issue to be the back of the control itself. Was cracked in a few places.

 

Would work as it should if I left it loose at mounting screws what hold it to the dash. Tighten those down, it no work.

Can't say there was vacuum leak noise as it has been a few years back.

[Keep it in the Family]

So I looked around yesterday and found vacuum operated actuators under the driver-side panel. Didn't get to vacuum test anything b/c I cannot loan a vacuum pump and don't want to spend the money to buy a hand pump right now. 

 

I also pulled the cover back that covers the top of the instrument cluster. It's the same piece that has three of the vents. Is the bezel/ plastic piece you guys mentioned connected from the back of that cover with screws, or can I pop it off the front; I mean is it held in with tabs instead? I don't want to pry and crack it.

 

Both these being said, the vacuum leak noise was not apparent yesterday. I forget to mention that this happens the worst when it is cold, it's especially bad when it's frosted outside overnight, and it was pretty warm out yesterday. 

 

*The cold aspect seems important..... sorry guys. Thinking old dried up hoses that may be cracked/hardened that is worse and cannot seal when it's so cold. The plan is to pull the hoses off and check the ends today, or wait till I hear the noise and put my hand against the connections to see if it changes the sound.

[firehawk618]

You found it leaking at the control unit, what more is there to troubleshoot?


To pull the whole bezel there are 2 screws on the bottom, 2 screws above the cluster, 2 screws on the defroster panel to get it out of the way and 2 screws on the heater control itself.

You have to pop off the top right and bottom left covers on the defroster side.

You have to pop off the off button and defrost button on the HVAC side.

[DaveT]

The bezel pops off.  Sometimes the little catches are sticky.  Just have to be careful, etc.  try pushing different angles, etc.  The post above tells about the screws, etc.

[Keep it in the Family]

To clear things up, I HAD NOT found the leak. It just wasn't apparent that day (it comes and goes). Yesterday it was back when I drove her last night so I put my ear next to the actuators under the driver panel, and the heater controls on the dash. It definitely sounds like its somewhere near the controls, so off it's coming today. I also got a hold of a hand vacuum pump.

 

Thanks for instructions in removing the bezel. Like I said, the first time it didn't quite come off. I have a good feeling about today though! 

[Numbchux]

I had a few that had stopped working because the vacuum switch in the control head was leaking. I have pulled them apart a couple times, and tried to reseal them, without luck.

 

On my last EA82, I did a little trial and error, but bypassed the whole control head with a vacuum tee fitting, so that it was always in heat/defrost. You only use function of the 2 vents right over the radio, and recirc.

[Keep it in the Family]

That is exactly what happened Numbchux. The control box leaks when it's cold outside. I also vacuum checked all the hoses and they all hold without leaking, plus they are not brittle which is good to know. Now I either need to go to the junk yard looking for a new box or just T it off like you did.

 

Thanks everyone.

 

Oh, and I removed the dash without breaking anything. Yesssss!