How to use heater controls

[macutmore]

I have just taken the opportunity to remove my plenum panel for cleaning and have made note of the specifications of the original rubber blocks for future reference, since it is unlikely anyone may ever come across original replacements.

The flexible Unipart rubber blocks adhered on each corner edge of the panel consist of two shaped pieces each side that are sandwiched together with contact adhesive. The individual pieces for one block each side consist of two 8 mm thick slices of flexible rubber (total thickness glued together 16mm). The five edges of the dimensions are...

UK RHD Offside sandwich (individual pieces 8mm thick)

94mm x 59mm x 42mm x 52mm x 39mm sandwiched with
94mm x 42mm x 37mm x curve cut (The overlap is where the contact adhesive is applied to adhere to the plenum panel INSIDE edge).

UK RHD Nearside sandwich (individual pieces 8mm thick)

85mm x 59mm x 42mm x 38mm x 47mm sandwiched with
85mm x 42mm x curve cut (Overlap is again where the contact adhesive is applied to adhere to the plenum panel INSIDE edge).

A large T-cutting aperture slit (see photo) is sliced into the centre of each side for bonnet release cable and wiper motor rack piping. Nothing is actually cut out of the slabs. It is only the slit that angles out to allow through the piping and cable as necessary.

It should be noted that with these blocks fitted correctly, it is extremely difficult to even refit the plenum panel back on the car!

[RobPue]

I have had the same problem, with the fresh air always coming through hot. It's hard to drive during hot summer days because you just sit there and bake in the sun with hot air blowing on you!

I bought a copy of an old car magazine, Car & Driver, I think, which contained a review of the TR7 convertible when it was new. One thing they mentioned in that review was that the fresh air seemed to be heated from somewhere inside the engine, and that it always blew hot air, always a little hotter than the outside air.

It was helpful to note I was not going crazy -- seems these cars are made this way!!

[Hasbeen]

Rob, if you pull a heater unit, out of a 7/8 you will find the foam
on these flaps, designed to seal the cold/hot air flow, will crumble
at first touch. The flaps just don't work properly any more,
allowing heat in, when it is supposed to be shut out.

You can remove the unit, replace this foam, & refurbish the thing,
in about 12 hours work. Or you can bypass the the heater unit hot
water, from the head to the pump, for summer, & reconnect the unit
for winter. This requires about 10 minutes, twice a year.

Even with the unit in very good condition, I always found it took
about 5 Km for the air to get fully cool, after a stop, of more than
a couple of minutes. There is a heat sink type of thing going on
there.

I never reconnected my unit, but where I live, we only get down to
32F a couple of nights a year, & even mid winter, most days are 70F,
or above.

Hasbeen

[bottomtop]

I it possible to open to outside air without the blower motor running on your cars? On mine, all through the long gap between the "max" fan setting and the "3" fan setting the blower motor is running. Is that normal?

[jclay (RIP 2018)]

No, you can not open the outside air with out turning on the blower.

Yes, the blower will run from the MAX position all the way down to the one position.

Now, you could disconnect the linkage and open the external door, but it would be a pain to get to and that lever is already very brittle and brakes easily.

[Hasbeen]

I don't think thats right jclay. Our 7, & 8 can both be opened, with
out the fan on.

I can't say for sure, as someone may have fitted an Oz
aircon/ventilation unit to our US import 8, before we got it, but
its ventilation is the same as our Oz ones.

The air inlet flap is fully open after the control lever is 1,75
inches down from the top "OFF' position. It is still well clear of
the first fan switch position. The flap is 3/4 open after a very
small movement of the control lever.

I had one 7, where the control lever slowly worked its way down,
under its own weight, & would engage the first [slow] fan switch.
There are three seperate switches, & its very easy to renove the
electrical connecter from the first one, leaving the medium, & high
speed fan settings still available. The lever will then lock in the
first fan position, with no fan running. You could use this trick,
if you had to.

Hasbeen

[samco]

Hasbeen I would concur with that. I recently rebuilt my with all new foam seals and had a spare heater as a reference. When you slide the control down that switches the fan on the flap which is visible under the bonnet (hood) inside the fresh air scoop can be seen to be fully open just before the first fan speed. The flap does not open any further between the three fan speeds.

If it doesn't fit you obviously need a bigger hammer.

www.metronewquay.co.uk www.wheelintheheel.co.uk

Check out my album

http://s163.photobucket.com/albums/t299/samco_bucket/

My youtube progress http://www.youtube.com/watch?v=4kMDqLU1N7Y



1980 Californian import converted to right hand drive V8. Under construction.

[bottomtop]

Perhaps there are different versions?

Mine is like this (crude)

- OFF
|
- MAX
|
|
|
|
|
|
|
|
- 3
|
- 2
|
- 1

Fan runs all the way between MAX and 3, almost no travel between OFF and MAX

[Hasbeen]

That's interesting, bottomtop.

I just got out my 1979 Leyland TR7 owners hand book, & the
ventilation instructions , & fan control are as I, & samco said. The
fan controls are 1 to 3, slow to hot, in the bottom quarter of the
lever travel. I wonder if the difference is a US thing, or a "parts
bin" change.

Check if your unit has the 3 seperate switches, & power connections,
as ours do. If you do, remove the connection to 3, & you should have
ventilation, without fan.

No wonder we sometimes give poor advice, we're talking about
different bl@@dy things.

Hasbeen

[trphil]

As far as I know there are two different versions, one for air con cars as shown by bottomtop and the non air con version as described by Hasbeen. I've never played with the air con version but I believe that the other three sliders are the same in both versions, therefore you will be able to get unheated/uncooled ram ventilation though the vents in the centre of the dash from both systems without the blower on.

[FI Spyder]

Thought I'd wade in here to thoroughly confuse this confused issue. I'm on vacation so don't have access to my TR7 drivers manual (I didn't take the 7 because we had an extra passenger and we travel with our cats.) From memory, only the out side vents have cool air going through them (talking A/C system here) but the cooling system aerodynamics are so bad you don't get much of a boost from that with out the fan so if you want any "cool" air you pretty much need the A/C on. This is slightly different than non A/C cars I believe. I'm under the impression coupes have side foot well air vents (?). So effectively speaking, if it's warm out you have the top down, if it's hot out you have the A/C on (top up or down) if it's cool out you have the top down, heater on, if it's cold out, you have the top up and heater on. Those are the real temperature controls. Anything else is an exercise in futility.

TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

[jclay (RIP 2018)]

Reread my manual. In the MAX position, the interior air is recycled and as you move down to the "3" position, out side air is introduced.

Now, If you open the vent lever, you are still recycling inside air, but as you move the fan lever down, you get the outside air.

Doesn't seem to mater as I get hot air from the system all of the timeexcept in the winter, when I get nothing but cold air.