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[underi]

Like the title says, I'm not getting almost any heat inside at all. I've replaced the heater matrix thinking that it was the culprit. The old one WAS leaking and clogged from some kind of headgasket sealer, but I'm still not getting any heat. There's a loose vacuum hose (?) that's black with a blue line that has been blocked off with a bolt from the previous owner. Nearby is a vacuum actuator connected to what I'm guessing is the recirculation system. So I'm guessing not very important. Above the heater matrix are 3 servo actuators with one of them having a broken connector just hanging. I connected it back, but no heat. Doing the climate control "reset" by pressing auto and off at the same time makes the servo with part number 090512500 move but the two other's do not. The servo that had a broken connector was numbered as 090512499.

Here's a picture of the servo with broken connector.


Is there any info on what exactly these different servo motors adjust? Which one might be responsible for mixing heated and cold air?

[Migv6 le Frog Fan]

Any help ?
https://www.youtube.com/watch?v=fq9leYUzAIY

The actuator arm in the video isnt easy to see when your in the car. Also a much more obvious one connected to the same servo which operates a flap nearer to the driver.
The one in the video had come adrift on my car and I had the same symptoms as you. It took quite a while to find it.
In fact I only found it once I discovered that video on youtube.

[underi]

Any help ?
https://www.youtube.com/watch?v=fq9leYUzAIY

The actuator arm in the video isnt easy to see when your in the car. Also a much more obvious one connected to the same servo which operates a flap nearer to the driver.
The one in the video had come adrift on my car and I had the same symptoms as you. It took quite a while to find it.
In fact I only found it once I discovered that video on youtube.

This is the one directly under the heater matrix, correct? I'll have to check the arm. How would I know to test this? Just turn heat to LO and HI and see if it moves?

[biggriffin]

Possibly airlock in system,

[Doctor Gollum]

Does the HBV have a vacuum line connected to it, and is it even fitted or connected incorrectly?

For a function test apply a vacuum to it and you should get heat.

[Migv6 le Frog Fan]

Any help ?
https://www.youtube.com/watch?v=fq9leYUzAIY

The actuator arm in the video isnt easy to see when your in the car. Also a much more obvious one connected to the same servo which operates a flap nearer to the driver.
The one in the video had come adrift on my car and I had the same symptoms as you. It took quite a while to find it.
In fact I only found it once I discovered that video on youtube.

It comes from up above the matrix, runs down alongside the rear of it, then bends around to connect to the servo motor.
You need to get your head down on the floor and shine a torch in there to see it.

This is the one directly under the heater matrix, correct? I'll have to check the arm. How would I know to test this? Just turn heat to LO and HI and see if it moves?

Yes just turn from Hi to Lo and it should move. If it isnt moving take the servo motor off and reattach it.
The other part connected to the same servo is different. Its actually a metal rod which goes to a flap on the cabin side.
As can be seen in the video, the matrix pipes give you the location to look at for the black plastic connector.

[underi]

Yes just turn from Hi to Lo and it should move. If it isnt moving take the servo motor off and reattach it.
The other part connected to the same servo is different. Its actually a metal rod which goes to a flap on the cabin side.
As can be seen in the video, the matrix pipes give you the location to look at for the black plastic connector.

The lever seems to be moving fine. I noticed that when it goes to the "high temp side" air flow from vents decreases signifcantly.

[underi]

I'm really at my wits' end here. The heat seems to work at least on some level once the car gets real hot and temp gauge is above 90C. Otherwise there's barely any heat at all. I forced the vacuum actuator in the passenger footwell to be halfway open with zipties and that seemed to help with the airflow problem, but the heat still doesn't REALLY work. Someone has mentioned the engine temperature sensor that's below the intake plenum in the back of the engine block, that they had it replaced and that helped. I just fail to see how engine temperature sensor and the reading to the ecu would significantly affect cabin heating. Mixer servo also seems to be working so I really have no clue what the problem is. So we have airflow, we have a hot matrix, we have the servo mixing and redirecting hot air to be used. What next?

[Doctor Gollum]

There are two temperature flaps, one in each foot well.

The fact that you got some heat on one side by forcing the lever tells you two things:

1. Neither of these actuators are working correctly.

2. You have found the source of the problem.

The solution is to find out why they don't work and fix that.

Needs some in-depth diagnosis with live climate control data.

[underi]

There are two temperature flaps, one in each foot well.

The fact that you got some heat on one side by forcing the lever tells you two things:

1. Neither of these actuators are working correctly.

2. You have found the source of the problem.

The solution is to find out why they don't work and fix that.

Needs some in-depth diagnosis with live climate control data.

The mixing flap isn't vacuum actuated, right? It's an electric servo motor, which when I checked seemed to be moving perfectly fine. I was thinking about maybe it being the engine temp sensor in the sense that ECU might not send a signal to the HBV to redirect hot coolant to the heater matrix before the car is really up to temp. I'll keep digging.

[Doctor Gollum]

The HBV IS vacuum operated.

The climate panel controls a vacuum switch which regulates the vacuum supplied to the HBV.

No vacuum, no heat control.

[underi]

The HBV IS vacuum operated.

The climate panel controls a vacuum switch which regulates the vacuum supplied to the HBV.

No vacuum, no heat control.

So you’re saying it’s the HBV? The pipe that leaves from the bottom seemed significantly colder after a drive, is that the one that goes to the matrix? Couldn’t really see much if it is or isn’t the one. With no vacuum it bypasses the heater completely?

[Doctor Gollum]

I am saying that a vacuum leak on that line between the vacuum system and the HBV would give the issues you are describing.

If the hose that is cold goes directly to the bulkhead connection then yes, that's the matrix supply.

The vacuum system includes the following:

A reservoir
Manifold connection at the one way valve by the brake booster
A vacuum switch controlled by the Climate Panel
At least three pieces of vacuum hose
The HBV

A failure at any one of those will prevent the HBV from operating correctly.

The fact that you are reporting no other running issues suggests that the problem is between the vacuum switch and the HBV again including both components.

The HBV can by easily tested by applying a different vacuum to it... ie sucking on the vacuum switch end of the hose and seeing if the heat returns.

[cam.in.head]

hi sorry to jump in . just to confirm out of interest cos ive seen conflicting answer in another post many years back .
does the heater bypass valve send heat through the matrix when vacuum is applied or does it bypass it when vacuum is applied ?

[cam.in.head]

from the previous post in 2010 by 'alanK46'


As the name implies, when heat is not required the valve bypasses the hot water from the engine so that it does not pass through the heater matrix.  Its controlled by vacuum.  No vacuum applied equals heat, vacuum applied equals no heat.  (That reminds me I removed the vacumm pipe on my car last winter to get some more heat, I must go and reconnect it now!!)