Extremely hot heater matrix. Hot in cabin.

[Wil2k]

Hi all.

Have just picked up our new / used 2002 Disco 2.
When I bought it I was aware the air-con needed attention, but after a long drive and some further investigation, it turns out it may be the heater matrix at fault.

It's getting hot, very hot, and once it heats up, the cab stays hot on the drivers side. Cool air flows from the top vents but down in the drivers footwell it's quite warm.

When I pulled it apart to look around I noticed the Heater Matrix was still very hot to touch after it had been parked for a while. I've looked at other threads on here but haven't as yet figure out what to do here.

Could it be:
a) reversed in/out line to the matrix
b) an airlock
c) something else in the matrix / lines
d) something horribly expensive

I've read that people bypass the matrix, I would prefer to track down the cause and deal with that if possible.

Other than that the new car is kicking butt so far! Loving having a Disco back! It actually handles better on the high way than our old one by a long shot!

Cheers

Wil



:-)

[greg smith]

I've had my 02 D2 since 04 always had this problem, hot air from the centre floor consul only when the aircon is off so-----run with the aircon on. Somewhere back in the dark future I read on the forum that it was something to do with a build[fitting] problem that required removal ofthe consul.:)

[Wil2k]

My problem actually occurs with the aircon going full-tilt and only on the drivers side. Had to keep opening the windows! :eek:

Wil

[woko]

Your heater matrix will get hot. Coolant is always flowing through it, there is no tap to turn coolant flow off. You could fit a tap and it would help.

[Wil2k]

Your heater matrix will get hot.

Yeah but this is unbearably hot. Wind the windows down and drive fast kinda hot. The aircon cant keep up with it. I wonder if there's a block that is preventing flow through the matrix. Perhaps the engine is running too hot? The temp gauge stay firm in the middle.

Wil

[clubagreenie]

MY temp gauge hit the middle at 55 deg and stays there over 100 so it's up there with diet croutons as far as usefullness goes.

You could get a hose with a 180 bend in it, by memory late RRC's had one of their heater hoses that you could cut back and use two link the to tubes.

[Wil2k]

... so it's up there with diet croutons as far as usefullness goes.

I laughed out loud at that! :D Diet Croutons!!

[bee utey]

Either you need to find the flap in your heater that is sticking, or you fit a 4 port heater control valve from a VT Commodore. It requires a switched vacuum supply which you can organise with a vacuum solenoid and a dash switch. Then your heater core remains cold at all times when you want cooling. Very cost effective repair.

[Wil2k]

Either you need to find the flap in your heater that is sticking,

Don't the flaps only direct air coming through the vents? The side of the matrix is really hot - too hot to touch, it's heating up the center console too. There's warm air in the vents, but you can still feel the cool from face level vents. It's pretty much the heat from the side that is warming things up as far as I can see.


or you fit a 4 port heater control valve from a VT Commodore...

Brilliant idea!

I'm a bit hell bent on finding the actual cause though, as my old disco's aircon & heater were great! I wonder if something has been connected arse about face when it had it's last visit to the disco doctor.

Wil

[clubagreenie]

There's nothing in water plumbing to really screw up unless you can mix up 2 hoses :confused:. Even if you did cross them it's only water in/out.

I also like the 4pt tap idea. Where would you find a small on/off vac switch for it?

[bee utey]

Where would you find a small on/off vac switch for it?

Any sleazy wrecking yard, they are commonly used to switch on emission control devices, a/c fast idles etc. Most Mazda /Laser vehicles have a couple screwed to the firewall, I think even some D1's have one on top of the charcoal canister. You need the vacuum supply to be off a reservoir/heater control system otherwise whern you accelerate the vac disappears and the heater comes back on!

http://www.aulro.com/afvb/attachment.php?attachmentid=32514&stc=1&d=1295306321


Pic shows an installed 4 port valve where the lpg was installed in the heater circuit, and I wanted flow to continue when the heater was turned off. It would easily go in the twin heater hose system on the D2. Only thing is hose size, this is 16mm. I don't know if there is a 19mm version, would be worth checking with a catalogue or parts store.

[SO69WA]

my 2c, is that the ventilation system is not closing off the heater air flow port , the heater matrix is actively hot at all times as part of the quick warm up cycle thru the thermo-stat, its the primary coolant circit,radiator for the motor, with the main radiator at the front of the car as the back up,
have you tried cycling manually thru the ventilation output settings, instead of leaving it on auto air, that may free it up, and yes the aircond will never beat the heater matrix at full ever,

[SO69WA]

FYI

Heater matrix

The heater matrix is fitted in the heater assembly inside the passenger compartment. Two pipes pass through the
bulkhead into the engine compartment and provide coolant flow to and from the matrix. The pipes from the bulkhead
are connected to the matrix, sealed with 'O' rings and clamped with circular rings.
The matrix is constructed from aluminium with two end tanks interconnected with tubes. Aluminium fins are located
between the tubes and conduct heat from the hot coolant flowing through the tubes. Air from the heater assembly is
warmed as it passes through the matrix fins. The warm air is then distributed in to the passenger compartment as
required.

+ HEATING AND VENTILATION, DESCRIPTION AND OPERATION, Description.
When the engine is running, coolant from the engine is constantly circulated through the heater matrix.



HEATING AND VENTILATION

80-6 DESCRIPTION AND OPERATION

Control flaps

Control flaps are installed in the heater assembly to control the temperature and distribution of air. Blend flaps control
the temperature and distribution flaps control the distribution.

Temperature and distribution control

Figure shows flaps set for medium heat to face level and footwell outlets

1 Windscreen/Side windows outlet

2 Heater assembly casing

3 Air inlet

4 Heater matrix

5 Front footwells outlet

6 Rear footwells outlet

7 Face level outlet

Blend flaps:Two sets of three blend flaps, one LH and one RH, regulate the flow of air through the heater matrix and
a heater matrix bypass, to control the temperature of the air leaving the heater assembly. The two sets of blend flaps
operate independently to allow different temperatures to be set for the LH and RH outlets.
Each blend flap is attached to a spindle. The end of each spindle extends through the side of the heater casing and
is attached to a common lever mechanism on the related side of the casing. A control cable is installed between the
lever mechanism and the related temperature knob on the control panel. When the flow is split between the bypass
and the heater matrix, the two flows mix downstream of the heater matrix to produce an even air temperature at the
individual outlets.

Distribution flaps: Separate distribution flaps are installed to control the flow of air to the footwells, windscreen/side
windows and the LH and RH face level outlets. The distribution flaps are attached to spindles that extend through the
RH side of the heater casing and are attached to a common lever mechanism. A control cable is installed between
the lever mechanism and the distribution knob on the control panel.

[ozscott]

Must be problem mate. My D2 is never hot on the floor vents unless heater is on. My D1 gets warm around the trans tunnel but I have always put that down to the auto and different design whereas my D2 manual is cool.

Cheers

[Wil2k]

Thanks for everyone's input. I appreciate you all discussing it with me.

Had I not had a D2 whose aircon was excellent previously, I'd accept the "that's just how it works" angle some of you have suggested.

I've done some googling and come up with another possibility. It seems some people have had the issue when there's an air-lock in the heater matrix. Eg after a poor bleeding when it has been disconnected (and I know this one has been).

I gave it a half arsed bleed last night and it seemed to improve, but the ambient temp outside was way down also. I might disconnect the heater matrix and flush it and see what happens.

Anyone got a suggestion for removing a rubber hose that wont budge?

Wil

[bronson]

Hi Wil2k<

Just wondering how you went, as Im currently going through the same thing after getting my car back after having the core replaced it sometimes gets really hot on the side of the tunnel at my feet.
Was going to have a poke around before taking it back to the machanics.
cheers

bronson
:)