Precat heater controls(part B)??
Discussion
With thanks to barreti for answering my previous question(see earlier post)
I was into the car to sort things out..............!
OK,Fan is working but only on its fastest speed??
Vents selection switch is working (servo/motor can be heard operating no prob's)
Hot/Cold switch is dead???? Any suggestions as to what to investigate first to....
1)GET SWITCH WORKING?
2)GET SLOWER SPEEDS WORKING(not that important)?
Thanks again
Rob
I was into the car to sort things out..............!
OK,Fan is working but only on its fastest speed??
Vents selection switch is working (servo/motor can be heard operating no prob's)
Hot/Cold switch is dead???? Any suggestions as to what to investigate first to....
1)GET SWITCH WORKING?
2)GET SLOWER SPEEDS WORKING(not that important)?
Thanks again
Rob
Exactly the same as mine Rob! I have had alook at the system and I have come to the conclusion that the valve which the servo gets stuck with corrosion/scale if the car has been sat for a while. The valave is located in the passenger footwell, over the battery I think, or there abouts. I have concluded that either you have to replace the valve or at least disconnect it and then clean it to free it up. The down side is that this requires draining the coolant. 
Worst case scenario is that the valve is stuck and the motor/servo has blown. I haven't gotten around to fixing it yet, another job for the list.
Worst case scenario is that the valve is stuck and the motor/servo has blown. I haven't gotten around to fixing it yet, another job for the list.
Thanks Chris,
A further question then based on your findings........
The bible says to fill the coolant system with the heater set to hot!
I have no intention of trying to repair this (whatever the problem) as I only want to set the heating to hot to sort the cooling filling out,no way I will ever need to use it after that as the car only gets used on Warm (if we ever get any) summer days.
A further question then based on your findings........
The bible says to fill the coolant system with the heater set to hot!
I have no intention of trying to repair this (whatever the problem) as I only want to set the heating to hot to sort the cooling filling out,no way I will ever need to use it after that as the car only gets used on Warm (if we ever get any) summer days.
I'm not too sure where my heating is actually set to but I just beld my system the same anyhow, seemed to cure the small overheating issue i had. If you wanted you could probably disconnect the servo arm from the heater valve and try and manually move the valve to open, but I'm not so sure of this as I haven't looked at it for a while, I can't even remember if there is a servo arm.
Mine's always worked, so I can only be of limited help...however:
The precat system uses no clever control box like the 500s. Instead you've got Cavalier window switches operating motors to adjust(a) the vents, (b) the heat; using servo arms. The motors turn when the switch is pressed appropriately, until the servo arm depresses a microswitch. Then the motor will only turn back the other way.
So...
it's possible (most likely I should think) that the heater valve is stuck, like Wildfire says in which case you might get away with moving the motor/servo arm by hand - if the motor is not powerful enough. It's also possible that the microswitch is broken, or one of the connections has come off. Best thing to do is have a look at the pipework above the battery/footwell, work out what's going on and take it from there.
I leave my heater 'on' as then I don't have to worry about the coolant and it's about as warming as a hamster's breath anyway.
The precat system uses no clever control box like the 500s. Instead you've got Cavalier window switches operating motors to adjust(a) the vents, (b) the heat; using servo arms. The motors turn when the switch is pressed appropriately, until the servo arm depresses a microswitch. Then the motor will only turn back the other way.
So...
it's possible (most likely I should think) that the heater valve is stuck, like Wildfire says in which case you might get away with moving the motor/servo arm by hand - if the motor is not powerful enough. It's also possible that the microswitch is broken, or one of the connections has come off. Best thing to do is have a look at the pipework above the battery/footwell, work out what's going on and take it from there.
I leave my heater 'on' as then I don't have to worry about the coolant and it's about as warming as a hamster's breath anyway.
llanelli-rob said:
Cheers Ben,need to get down into that footwell anyway to sort the wiring out someone in the past has left it in quite a state
So two birds one stone I guess
Rob
Guys ,there seem so many of us , maybe we should ask for a precat forum all of our own............
After all there are som many differences..
No Rob, it's not difficult to get at, and I've not taken the battery out of my car ever!
To get the valve out, try pulling off the pipes, then bend them in half and tape them in that position, the water wont get out. Cover everything with towels just in case though
If you are unsure if there is crap in the valve you can then unplug the electrical connection and pull it out. Honestly, you will have it out in 20mins max. and while you have it out you can have a look at the micro switches too because they get kicked etc and sometimes crack then stop 'stopping' if you know what I mean.
If you want to drop some of the water out of the pipes to make sure they are not full of crap, try getting a longish length of standard 15mm copper water/central heating tubing. it fits perfectly into the water pipes and you can then stick the tubing out of the door and into a bucket. I backflushed my heater matrix like this - with a bit of copper tubing into a bucket and another one attached to the garden hose!
Oh, this is the view through the valve and of the other side of the motor (just in case). I think that nipple thing you can see through the valve ensures it all closes and locks it into position - pressure and all that.
>> Edited by barreti on Wednesday 17th May 19:11
To get the valve out, try pulling off the pipes, then bend them in half and tape them in that position, the water wont get out. Cover everything with towels just in case though
If you are unsure if there is crap in the valve you can then unplug the electrical connection and pull it out. Honestly, you will have it out in 20mins max. and while you have it out you can have a look at the micro switches too because they get kicked etc and sometimes crack then stop 'stopping' if you know what I mean.
If you want to drop some of the water out of the pipes to make sure they are not full of crap, try getting a longish length of standard 15mm copper water/central heating tubing. it fits perfectly into the water pipes and you can then stick the tubing out of the door and into a bucket. I backflushed my heater matrix like this - with a bit of copper tubing into a bucket and another one attached to the garden hose!
Oh, this is the view through the valve and of the other side of the motor (just in case). I think that nipple thing you can see through the valve ensures it all closes and locks it into position - pressure and all that.
>> Edited by barreti on Wednesday 17th May 19:11
Right get the picture now....................
So am I correct in thinking that in the photos the valve is open therefore allowing hot water to the heater matrix.........
And if my levers are set in the same positions as yours show then I can be sure the control is set to hot and I can correctly bleed my cooling system!?
If that makes sense?
So am I correct in thinking that in the photos the valve is open therefore allowing hot water to the heater matrix.........
And if my levers are set in the same positions as yours show then I can be sure the control is set to hot and I can correctly bleed my cooling system!?
If that makes sense?
Yes, thats right Rob. It's a very heath robinson affair but it's clear TVR wanted something a bit different and this is what the engineers came up with. When it's all working its OK but things go wonky with it.
Referring to the first picture, I'll try to describe how it works:
The black arm on the left is attached directly to the spindle of the motor, it is held in place by the small black grub screw you can see at about 8 oclock. The silver arm on the right opens and closes the valve. The bar in between just joins them together. If you want to test your heater you can pop off the little clip securing the arm to the bar (they swivel around and clip over the bar, in the pic the silver arm end is off, the other is still attached) and pop the bar off, then move the heater valve by hand. Feeling the hoses will give you a clue to whether its open or not.
The micro switches switch off the motor when it is fully open or fully closed. The correct position is altered by adjusting that large screw on the black bar or by gently bending the micro switch arms.
Things that go wrong:
The grub screw comes loose and lets everything get out of alignment, you might want to check that.
The micro switches break. This can also then force everything out of alignment because the grub screw can't cope with the force of the motor. Easy to replace and get them from Maplin for tuppence.
Corrosion of the terminals. In the picture the blue terminals on the micro switches are new because mine were unbelievably corroded.
Ian.
Referring to the first picture, I'll try to describe how it works:
The black arm on the left is attached directly to the spindle of the motor, it is held in place by the small black grub screw you can see at about 8 oclock. The silver arm on the right opens and closes the valve. The bar in between just joins them together. If you want to test your heater you can pop off the little clip securing the arm to the bar (they swivel around and clip over the bar, in the pic the silver arm end is off, the other is still attached) and pop the bar off, then move the heater valve by hand. Feeling the hoses will give you a clue to whether its open or not.
The micro switches switch off the motor when it is fully open or fully closed. The correct position is altered by adjusting that large screw on the black bar or by gently bending the micro switch arms.
Things that go wrong:
The grub screw comes loose and lets everything get out of alignment, you might want to check that.
The micro switches break. This can also then force everything out of alignment because the grub screw can't cope with the force of the motor. Easy to replace and get them from Maplin for tuppence.
Corrosion of the terminals. In the picture the blue terminals on the micro switches are new because mine were unbelievably corroded.
Ian.
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