griff heater temp control

[alan c]

hi am looking any informatiom to help me with a problem i have on my 96 griff.The heater temperature control motor is constantley turning,the Steve Heath bible wireing schematic shows temp motor with micro switch same as direction control motor but also states two versions of electronic systems used,mine does not appear to have micro switches is there another wireing schematic.

[david beer]

There is a variable resistor on the heater valve, it has three wires, quite heavy cable and can break the tabs off it causing the valve to spin all the time. Take a look at it and if they are snapped off you can replace it quite easy.

[stringbag]

The knob is also a variable restistor and the same thing can happen to that. If what david suggests doesn't cure it, it will be the knob. Take the panel out of the centre console and re solder the contacts onto the circuit board (not difficult). For info on how to get the centre bit out, see thegriffithpages.co.uk (BB's excellent site) or it is in the bible.

[alan c]

David & String bag, thanks for the advice i will give it a go,and will let you know how i manage.

[alan c]

hi have had a look at connections on heater valve, and with heater panel out switch to circuit board both seem ok.I gues there must be a component gone,anyone know how to test.also would help to know the theory as to how the system works.

[jeboa]

Alan,

I am having heater problems at the moment. Once I have it solved I am going to do a couple of web pages on fault finding.

I would agree that one of the variable resistors (pot) is broken. There is a 10k pot on the control board and a 10k pot connected to the motor that moves the valve.

With the engine off, ignition on turn the switch one way and then the other. Can you hear the motor changing direction?

If you have the control panel out you can test the pot using a multimeter.

I WOULD RECOMMEND DISCONNECTING THE VEHICLE BATTERY BEFORE ATTEMPING ANY OF THE FOLLOWING!!



Set the meter to resistance and place the probes across the the resistive material (between A and B). It should read 10kOhms. The pot is a linear type, which means the resistance varies directly in relation to the knob. Set the pot to the middle point. Connect the meter between either A or B and W. You should measure around the 5kOhm point. This should check the pot out.

The controller unit is behind the dashboard. It has the ribbon cable running to it, a 10 way connector, a two way connector and three ouptuts to the 'servos'. Each servo has 5 wires.

Red - DC to motor
Black - DC to motor

White - W )
Blue - A }- Pot
Green - B )

Determine the connector that operates the heater valve and check the pot using the procedure above and see if it checks out. If you are feeling brave you could connect a 9v PP3 battery to the red/black wires to momentarily drive the motor. After driving the motor for 0.5secs the resistance between W/A or W/B should have changed.

I suspect that the pot in the servo is the problem.

[david beer]

I will try to help, the variable resistor tells the "brain" where the valve is, ie open or closed, or of course anywhere in between. The variable resistor is a 10k and should cost around 2p, there were a couple of pyhsical variations, 10mm being more common, but then again it is a TVR and i am sure some are different again. It will come away from the valve, a single self threaded screw will hold it in and will come off the spindle, you can then measure it, of course unless you have a soldering iron, thats as far as you can go. There is also the chance that the motor is spinning but not turning the valve because the grub screw that keeps in place has come loose, my Griff is away being "Taraka'd" at the mo so i think thats right.

[Mutant Rat]

As David Beer says, check that it isn't just a loose knob, first.

They are fixed on using a small allen-headed grub screw (you are quite right, David!), and if this is a little loose, the knob just rotates on its shaft.

[alan c]

thanks every one for the help.I will check this and
report my findings.
as regards hearing the motor turning one way or the other when turning the switch,when the problem first started to happen yes, and the switch worked fine but intermittently i could hear the motors working on their own,this lasted a week or so, but now the motor just spins in one direction all the time no matter where i turn the switch.
also any suggestions or recommendations on where to get the parts.

[dcl5ah]

The problem looks to be the trimmer on the heater valve motor which is as everyone said a 10k pot 15mm diammeter, next question is are these single turn or multi turn ones.

on behalf or alanc

Ash

[jeboa]

There was a link posted somewhere on the forums that pointed to a 15mm 10K pot supplied by Farnell (www.farnell.co.uk), this is discontinued now - they only have 10mm models in stock.

RS Components ( www.rswww.co.uk ) do a 12mm vertical pot that I think may do the job - RS Stock no: 393-857 . It has a metal cage around it, but this can be trimmed down to fit. The important bit seems to be the wiper control - it would be easy to connect this to the existing mechanism, using the spindles ( see bottom of page at : http://rswww.com/cgi-bin/bv/rswww/subRangeAction.do?catoid=-1600758197&cacheID=ukie ) Cut and paste this link or it won't work.

[dcl5ah]

Finally we are on the last leg of this one, Ive traced alans problem to the heater brain and now everything is working, only thing is when I removed the brain the 2 wires on spade connectors fell orr one is black the other is black with a green or yellow trace. Can anyone tell me which wire goes to which connector. Thanks in advance Ash

[jeboa]

This is from BB's site:



The Black is GND the balck/yellow is +12v.

One word of caution - my control unit had been disconnected when I bought the car. When I connect the unit with the wires as above the fan works fine, the other way round it doesn't (runs at constant slow speed).

The wires are directly wired to the MOSFET that is connected to the heatsink. When they are wired in the way shown above the heatsink becomes 12v live!! Try it with a multimeter before you shove it back in the dash.

Hope this helps - could you post back your results.

>> Edited by jeboa on Monday 11th July 23:32

[shadowfax]

Impressive stuff lads!

Two things:

Firstly, when I was driving home the other night, I heard the whirring of the temp change dial motor doing it's thing as if it had been turned the other way, when I hadn't touched it. Is this summat to do with the car checking the outside temp? It wasn't cold, but maybe there was moisture / condensation in the gubbins. Never worried me either, but seeing as how the heated mirros come on & go off as they please, there may be a link i.e. good ol' TVR electrics

Secondly, How DO you post pics straight onto the post?

[jeboa]

To post pics just use this:

[pic] www.website/picture.jpg [/pic]

replacing the bit inbetween with your url.

Unfortunately this means you must have the picture you want posted uploaded on to a computer on the internet.

I think there is a tutorial on here somewhere......(anyone?)

[shadowfax]

thanks for that Jeboa

[pebbledash]

shadowfax said:

Impressive stuff lads! when I was driving home the other night, I heard the whirring of the temp change dial motor doing it's thing as if it had been turned the other way, when I hadn't touched it. Is this summat to do with the car checking the outside temp? It wasn't cold, but maybe there was moisture / condensation in the gubbins. Never worried me either, but seeing as how the heated mirros come on & go off as they please, there may be a link i.e. good ol' TVR electrics

sounds like dodgy wiring or a conector, mine used to do that, cleaned all the conectors etc, and it started working as normal, aslo the valve that controls the hot water flow into the heater matrix, goes out of sink, you then end up with heater that has a scale that goes hot to very hot then back to hot again. there are two tipex marks on it that line up when in the cold position.
That pic on BB's site is of my car when i had it in bits, there are more if anyone need them

[jeboa]

Pebbledash,

Could you email those pics you have to me please

Thank you.

[richb]

Also see www.pistonheads.com/gassing/topic.asp?t=192621&f=9&h=0 Rich...

[pebbledash]

jeboa said:

Pebbledash, Could you email those pics you have to me please Thank you.

ok, but it may not be till monday, they are quite large..