Heater problem...
Discussion
It turns out that you can have the best ECU in the world controlling the engine, but it counts for nothing if the heater packs up and you can't see where you're going... And even if you can, you'll freeze to death before you get there.
Damn. Another thing to fix.
Anyone know anything about the TVR environmental processor? (I.E. has anyone coded up a sensibe one on a microcontroller? And if not, would anyone buy one if I made one?
) Schematics would be a huge help.
The control pots seem to all work, so I'm guessing it's either the fan has died or the processor is acting up...
I don't need this! I wanted to be out mapping tonight!
Damn. Another thing to fix.
Anyone know anything about the TVR environmental processor? (I.E. has anyone coded up a sensibe one on a microcontroller? And if not, would anyone buy one if I made one?
) Schematics would be a huge help. The control pots seem to all work, so I'm guessing it's either the fan has died or the processor is acting up...
I don't need this! I wanted to be out mapping tonight!
LOL - have you seen the legend on the PCB - It's called a "processor" despite, as you say, being a collection of antique quad package opamps left over from ancient acts of boat building...
Trying to sort out a spec of things it needs to do:
So far I have:
User interface
Switches:
Fan on/off (plus heated mirrors on/off)
heated mirrors
heated seats
(AC on/off which I don't have)
Position ctrls:
Fan speed
Temperature selection
Air from outside/inside selection
Screen/dash/feet selection
Timers:
heated mirrors
heated seats?
Actuators
Fan driver (currently a N channel enhancement mode FET)
3x bi-directional motor drivers including 2 limit switches each (Can I replace these with stepper motors? - much more sensible)
heated seat relay driver
heated mirror driver (not a relay, but maybe it should be)
Whatever the AC needs (I don't know)
Can anyone add to this? I've not got one switch accounted for.
Maybe if I make my own, I could put a thermistor in the system somewhere so it could have closed loop fan and temperature control...
I feel another major mod thread coming on.
Trying to sort out a spec of things it needs to do:
So far I have:
User interface
Switches:
Fan on/off (plus heated mirrors on/off)
heated mirrors
heated seats
(AC on/off which I don't have)
Position ctrls:
Fan speed
Temperature selection
Air from outside/inside selection
Screen/dash/feet selection
Timers:
heated mirrors
heated seats?
Actuators
Fan driver (currently a N channel enhancement mode FET)
3x bi-directional motor drivers including 2 limit switches each (Can I replace these with stepper motors? - much more sensible)
heated seat relay driver
heated mirror driver (not a relay, but maybe it should be)
Whatever the AC needs (I don't know)
Can anyone add to this? I've not got one switch accounted for.
Maybe if I make my own, I could put a thermistor in the system somewhere so it could have closed loop fan and temperature control...
I feel another major mod thread coming on.
David,
I had the similar problem with my Grif, when I purchased it.
A basic description of the Environmental Control Unit is as follows:
There is no microcontroller in the unit, it's basically a bunch op-amps (L272M and LM324) a timer IC (NE555) and an N-Channel MOSFET (70N06).
There are three connectors on one the side - these are for the servos (5 wires to each), and a ribbon connector (to the control panel) on the other. At one end is a large heatsink, at the other end a large connector and two seperate wires with push fit spade terminals. The large connector (10 wires - I think) carries the power to the unit and switches the heated seats (and maybe the heated mirrors?).
There are three servos, 1 controlling the heater valve (up near the glovebox), one controlling the recirculation flap (next to the battery box) and another controlling the directional flap (up near the glovebox also). With the ignition on (engine not running - so you can hear them) can you hear the servos moving when you adjust the controls?
If you can hear the servos moving - you have power to the unit.
I had the similar problem with my Grif, when I purchased it.
A basic description of the Environmental Control Unit is as follows:
There is no microcontroller in the unit, it's basically a bunch op-amps (L272M and LM324) a timer IC (NE555) and an N-Channel MOSFET (70N06).
There are three connectors on one the side - these are for the servos (5 wires to each), and a ribbon connector (to the control panel) on the other. At one end is a large heatsink, at the other end a large connector and two seperate wires with push fit spade terminals. The large connector (10 wires - I think) carries the power to the unit and switches the heated seats (and maybe the heated mirrors?).
There are three servos, 1 controlling the heater valve (up near the glovebox), one controlling the recirculation flap (next to the battery box) and another controlling the directional flap (up near the glovebox also). With the ignition on (engine not running - so you can hear them) can you hear the servos moving when you adjust the controls?
If you can hear the servos moving - you have power to the unit.
The fan is controlled by a MOSFET (bolted to the large heatsink). This is connected to the fan buy two spade connectors at the side of the ECU. If you pull off the wires and connect them together the fan should turn at full speed. If it doesn't maybe the fan is seized (this is a common fault apparently).
The ECU controls the speed of the fan by pulsing the power on and off. Do a 'Google' for PWM DC Speed control to find out more. With the ECU plugged in and the ignition on you could place a DMM on the two spade connectors to see if you have a DC voltage. This should vary as you turn the fan speed control knob.
The ECU can be accessed by removing the radio, but is easier to work on if you pull the dash out slightly. To test the fan only, you can pull off the three servo connectors (make sure you label them) to get the unit out further. The box itself is a RS/Maplin jobbie with four screws to open it.
Hope this is of some help, I have a few sketches at home, and the data sheets if you require them. I also have a couple of spares of all the ICs including the MOSFET and MICA washers if you need them. Drop me an email if you need anything.
The ECU controls the speed of the fan by pulsing the power on and off. Do a 'Google' for PWM DC Speed control to find out more. With the ECU plugged in and the ignition on you could place a DMM on the two spade connectors to see if you have a DC voltage. This should vary as you turn the fan speed control knob.
The ECU can be accessed by removing the radio, but is easier to work on if you pull the dash out slightly. To test the fan only, you can pull off the three servo connectors (make sure you label them) to get the unit out further. The box itself is a RS/Maplin jobbie with four screws to open it.
Hope this is of some help, I have a few sketches at home, and the data sheets if you require them. I also have a couple of spares of all the ICs including the MOSFET and MICA washers if you need them. Drop me an email if you need anything.
Thanks. Useful to have some facts confirmed... Specially about the FET & PWM control.
I know there's no micro in the standard thing, but I may well code one up to take its place - it'll be a neater solution than messing too much with pre Noah's Arc electronics And I can have closed loop cabin temperature control too...
Spare components won't be a problem for me, but thanks for the offer. It's very much appreciated.
Looks like it's the FET that's fried... The other controls make a noise, but I wouldn't go as far as saying they work.
I know there's no micro in the standard thing, but I may well code one up to take its place - it'll be a neater solution than messing too much with pre Noah's Arc electronics
And I can have closed loop cabin temperature control too... Spare components won't be a problem for me, but thanks for the offer. It's very much appreciated.
Looks like it's the FET that's fried... The other controls make a noise, but I wouldn't go as far as saying they work.
One more thing....
When I examined my ECU the FET was bolted directly to the heatsink (with some thermal grease) with NO Mica washer. This meant that the Drain which is wired to be at +12v was making the heatsink live. Not sure if this was an original fault or someone had effected a repair prior.
I would be interested to see any closed-loop design you come up with, are you going to try and interface it with the valve control?
When I examined my ECU the FET was bolted directly to the heatsink (with some thermal grease) with NO Mica washer. This meant that the Drain which is wired to be at +12v was making the heatsink live. Not sure if this was an original fault or someone had effected a repair prior.
I would be interested to see any closed-loop design you come up with, are you going to try and interface it with the valve control?
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