MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: brianorme1986 on January 29, 2022, 23:33

Title: Heater unit?
Post by: brianorme1986 on January 29, 2022, 23:33
Hi all,

On my facelift, the left hand dial on the heater controls (the one which controls where the heat/air is pumped to) just spins around upon trying to turn it with no resistance.

I've taken the dial off and used a pair of long nosed pliers, and it just spins.

Do I need a new heater control/matrix unit? If so are they difficult to replace -I've done headunit swaps on the car before so fairly confident in Diy.

Amy advice is greatly appreciated

Bri
Title: Re: Heater unit?
Post by: Call the midlife! on January 30, 2022, 07:37
That's an unusual one, if I remember right the flaps are all cable controlled from the knob so it could be that the linkage has become detached somehow. I've seen people move the control knobs to different parts of the dash so it's probably an independent assembly rather than part of the matrix itself.
If I get time after breakfast I'll see what the green book says.
Title: Re: Heater unit?
Post by: Topdownman on January 30, 2022, 08:22
The shaft does come out if you twist it too hard. It may be that you need to dismantle it to see how it works. I think that by turning it to the left by say 30-40 degrees, you may be able to get it back in but the fact that it came out may mean there is something else wrong.
Title: Re: Heater unit?
Post by: Call the midlife! on January 30, 2022, 09:12
Removing the control unit isn't a massively difficult job, replacing it is more complicated as you have to make sure the knobs are in particular settings to reset the cables.
First try removing the glovebox door and having a look/feel at the cables to make sure they're all connected and nothing is flopping around.
To remove the control unit pull all the control knobs off and remove the screws holding the finish panel and disconnect the clock.
Disconnect the cables through the glovebox side and then remove the 4 screws, pull the assembly out and disconnect the 2 connectors.
Install is reverse but.
Air inlet to recirc
Temp to max cool
Mode control to face
There's an option to adjust tension on the cables but see if they're connected first.
Title: Re: Heater unit?
Post by: Carolyn on January 30, 2022, 09:55
Quote from: Call the midlife! on January 30, 2022, 09:12Removing the control unit isn't a massively difficult job, replacing it is more complicated as you have to make sure the knobs are in particular settings to reset the cables.
First try removing the glovebox door and having a look/feel at the cables to make sure they're all connected and nothing is flopping around.
To remove the control unit pull all the control knobs off and remove the screws holding the finish panel and disconnect the clock.
Disconnect the cables through the glovebox side and then remove the 4 screws, pull the assembly out and disconnect the 2 connectors.
Install is reverse but.
Air inlet to recirc
Temp to max cool
Mode control to face
There's an option to adjust tension on the cables but see if they're connected first.

This is very useful and concise.  I have added it to the 'how to' section.
Title: Re: Heater unit?
Post by: Call the midlife! on January 30, 2022, 10:26
Quote from: Carolyn on January 30, 2022, 09:55
Quote from: Call the midlife! on January 30, 2022, 09:12Removing the control unit isn't a massively difficult job, replacing it is more complicated as you have to make sure the knobs are in particular settings to reset the cables.
First try removing the glovebox door and having a look/feel at the cables to make sure they're all connected and nothing is flopping around.
To remove the control unit pull all the control knobs off and remove the screws holding the finish panel and disconnect the clock.
Disconnect the cables through the glovebox side and then remove the 4 screws, pull the assembly out and disconnect the 2 connectors.
Install is reverse but.
Air inlet to recirc
Temp to max cool
Mode control to face
There's an option to adjust tension on the cables but see if they're connected first.

This is very useful and concise.  I have added it to the 'how to' section.
It's condensed from the big book, the cables are seemingly adjustable but without ever doing it myself I'm not sure how "easy" it is as it looks like you have to do it through the hole at the end of the glovebox.

It involves holding a cable clamp on the assy in place and then moving the cable relative to the clamp. Not sure how much room there is for both hands, might need a veterinarian 😂
Title: Re: Heater unit?
Post by: Topdownman on January 30, 2022, 12:20
The shaft does come out....

(https://i.imgur.com/FTqkCZF.jpg)

New control units can be sourced from well known breakers for not too much money if needed.

(https://i.imgur.com/R1wKhxf.jpg)