AAAARRRRGH !! %^&*^%$ HEATER !
Discussion
One of these days I'll get this %^&*&^% heater sorted. Has anybody out there with a pre-98 V8 noticed that as the temperature control is turned to fully cold (click into place) and then back towards hot, there is a sensation of overcoming resistance at about the ten past position (ie a third of the way back towards hot). Examining the heater valve as my long suffering daughter (who hates my car and thinks it is crap (see accompanying thread)) turns the control, the valve operating arm reaches fully closed at the time of the click into full cold but then stays there until the knob is turned back beyond the ten past position (ie, the valve starts to open at the same time as the sensation of overcoming resistance but does not fully close until the knob is at the end of its travel when going the other way. In other words, once the valve is closed, it stays there and does not move even if the control knob is moved back and forth between quarter past and fully cold almost like there is free play in the cable mechanism.
Question is: is everybody else's like this and hence this is normal. It's been so long since I had a working heater that I can't remember !
In conjunction with this, the heater control jumps back out of the cold position if it has been previously on hot for more than a few minutes. Apparently this is pre loading of the cable by the heater thermostat. I have spent hours trying to work out how this thermostat operates but iut is beyond me and the manual supplement on heating is hopeless.
Question is: is everybody else's like this and hence this is normal. It's been so long since I had a working heater that I can't remember !
In conjunction with this, the heater control jumps back out of the cold position if it has been previously on hot for more than a few minutes. Apparently this is pre loading of the cable by the heater thermostat. I have spent hours trying to work out how this thermostat operates but iut is beyond me and the manual supplement on heating is hopeless.
Hooooray... a reply !!! It's really reassuring to know someone else has noticed the same thing. If you really want to know about the heater, you need a copy of Section PJ of the workshop manual plus the relevant parts pages (Which are actually very informative about the layout of the plumbing). This is one of four sections which are not included in the 1993 model year on workshop manual. (Airbag, engine management and brakes being the others.) As a matter of interest the CD ROM pirate manuals doing the rounds have the manual, the parts and the other three supplements but NOT the heater. I bought mine through the local dealer for about £15 ($25). If you e-mail me your address, I can let you know any details you need in particular.
For as long as I have owned the car, the heater has been crap. I attribute this to the heater matrix filling up with crud as a result of the cylinder liner failure which plagued early V8 engines (mine has been rebuilt by the factory) Since fitting the new matrix, the heater has been really good (well, eventually....but that's another story!!)I am now assuming that the thermostatic heater control is working for the first time and that this is the cause of the funny behaviour. Unfortunately, what with Esprits being so scarce, I can't ry another car to see if it's the same.
The factory couldn't really help (rare that, they're usually brilliant) and said that there is no diagram or description of operation of the thermostat. The workshop manual simply says that the thermostat senses heater output temperature and attempts to control the valve on the matrix to maintain the correct temperature relative to the position of the control knob. This makes no sense when you actually use it. For example, when the heater has been on fully hot for a while, it is quite difficult to get the knob to the fully cold position (so much so, that the knob jumps back out of the detente at the end of its travel) Now this would suggest to me that the thermostat is "fighting" any change in temperature by resisting closure of the matrix valve when the knob is moved from hot to cold. After a few minutes, this problem abates and the knob can be turned fully cold. Does this make sense ? The thermostat actually seems to resist change rather than assisting it. Surely a thermostat should make the heater "extra cold" until it reached the desired cool level. This is what happens with climate control-- Change the heater from 23 degrees to seventeen degrees in a hot car and the heater blows extra cold until seventeen degrees is reached. The Lotus system is almost saying "not yet" or "can we do this a bit at a time please !?"
For as long as I have owned the car, the heater has been crap. I attribute this to the heater matrix filling up with crud as a result of the cylinder liner failure which plagued early V8 engines (mine has been rebuilt by the factory) Since fitting the new matrix, the heater has been really good (well, eventually....but that's another story!!)I am now assuming that the thermostatic heater control is working for the first time and that this is the cause of the funny behaviour. Unfortunately, what with Esprits being so scarce, I can't ry another car to see if it's the same.
The factory couldn't really help (rare that, they're usually brilliant) and said that there is no diagram or description of operation of the thermostat. The workshop manual simply says that the thermostat senses heater output temperature and attempts to control the valve on the matrix to maintain the correct temperature relative to the position of the control knob. This makes no sense when you actually use it. For example, when the heater has been on fully hot for a while, it is quite difficult to get the knob to the fully cold position (so much so, that the knob jumps back out of the detente at the end of its travel) Now this would suggest to me that the thermostat is "fighting" any change in temperature by resisting closure of the matrix valve when the knob is moved from hot to cold. After a few minutes, this problem abates and the knob can be turned fully cold. Does this make sense ? The thermostat actually seems to resist change rather than assisting it. Surely a thermostat should make the heater "extra cold" until it reached the desired cool level. This is what happens with climate control-- Change the heater from 23 degrees to seventeen degrees in a hot car and the heater blows extra cold until seventeen degrees is reached. The Lotus system is almost saying "not yet" or "can we do this a bit at a time please !?"
Anyway, to answer your question, the heater valve is located in the driver's footwell. Are you left or right hand drive ? It makes no difference to the overall location but the manual is for LHD and some of the parts are mirror image whilst others are the same but located differently.
Whatever, the heater valve is fastened to the top of the footpedal box by a single stud. It can be seen from above. To do this, open the front boot and remove the cover of the fusebox on the driver's side. Remove the cover of the small fusebox on the bulkhead (fusebox A) and uscrew the two cross head blts holding the fusebox to the bulkhead. The nuts are captive so you shouldn't get a distressing tinkle as the bolts come out. Poke the fusebox into the footwell. (It is remarkably easy to get it back up in place !) Next, get a mirror about 10cm across (ideally on a stick, like a giant dental mirror) and slide it into the fusebox hole. Kneel down and look throgh the hole at a very shallow angle, use a torch and look towards the middle of the car (i.e., as if you were hiding behind the front of the car on the pavement looking across the road in a TV Cop style shoot out. At the same time, get an accomplice to turn the heater temperature knob back and forth. You should see the heater valve operating arm moving back and forth. If you are RHD, the operation is the reverse of the book. Movement towards you is to the hot position.
The purpose of the mirror is that you can slide it under the valve and view the operating arm rotating. Using a second mirror you can just about see the bit of the valve between the operating arm and the valve itself. I presume this is this goddamn thermostat thing. I managed to soak it with PTFE spray so lubrication isn't the problem.
As the knob is turned fromhot to cold, there is resistance to fully turning it to the end of the stop and the operating arm as seen through the A-HOLE (sorry, couldn't resist that !) anyway, as viewed through the fusebox aperture, the operating arm does not reach the end of its travel. After a few minutes, it will allow the knob to click to full cold and the operating arm reaches the fully cold position. On turning back towards hot, the arm sticks at the fully cold position. As the knob goes anticlockwise through the 2 o'clock position, the arm suddenly jumps to the one quarter open position. Now, remember that in RHD, to go from cold to hot, the cable is "pushing" the operating arm and therefore, there must be resistance to this movement. As I said above, the valve is almost trying to stop the driver from changing to a new temperature, or at least not quickly.
Maybe it's just a quirky system but it seems odd that when the driver tries to make the heater colder, the thermostat is tring to keep the valve in the hot position. It is definitely the thermostat as when viewed with two mirrors as above, you can see something sticking and then jumping sideways as th operating arm starts to move. You would think that when the car is hot and the driver selects cold, then the heater would be trying to go cold, not trying to stay hot !
Maybe it is like this: Car is hot. Thermostat keeps it that way. Driver selects a bit less hot. Thermostat adjusts to new temperature settin (taking three minutes to do so) and then maintains new temperature. As such, sudden large changes coukd not be accomodated. That's it ! That's the only answer. ..... A sudden flash of inspiration !!.......Then again, perhaps I'm totally wrong ! What do you think ?
Oh... and thanks once again for answering, it has inspired a possible answer. Like I saiod, e-mail or forum post me any specific heater stuff.
By the way, all of this is totally irrelevant for '98 MY onwards which used an electronic stepper motor to change the heater temperature valve !
Whatever, the heater valve is fastened to the top of the footpedal box by a single stud. It can be seen from above. To do this, open the front boot and remove the cover of the fusebox on the driver's side. Remove the cover of the small fusebox on the bulkhead (fusebox A) and uscrew the two cross head blts holding the fusebox to the bulkhead. The nuts are captive so you shouldn't get a distressing tinkle as the bolts come out. Poke the fusebox into the footwell. (It is remarkably easy to get it back up in place !) Next, get a mirror about 10cm across (ideally on a stick, like a giant dental mirror) and slide it into the fusebox hole. Kneel down and look throgh the hole at a very shallow angle, use a torch and look towards the middle of the car (i.e., as if you were hiding behind the front of the car on the pavement looking across the road in a TV Cop style shoot out. At the same time, get an accomplice to turn the heater temperature knob back and forth. You should see the heater valve operating arm moving back and forth. If you are RHD, the operation is the reverse of the book. Movement towards you is to the hot position.
The purpose of the mirror is that you can slide it under the valve and view the operating arm rotating. Using a second mirror you can just about see the bit of the valve between the operating arm and the valve itself. I presume this is this goddamn thermostat thing. I managed to soak it with PTFE spray so lubrication isn't the problem.
As the knob is turned fromhot to cold, there is resistance to fully turning it to the end of the stop and the operating arm as seen through the A-HOLE (sorry, couldn't resist that !) anyway, as viewed through the fusebox aperture, the operating arm does not reach the end of its travel. After a few minutes, it will allow the knob to click to full cold and the operating arm reaches the fully cold position. On turning back towards hot, the arm sticks at the fully cold position. As the knob goes anticlockwise through the 2 o'clock position, the arm suddenly jumps to the one quarter open position. Now, remember that in RHD, to go from cold to hot, the cable is "pushing" the operating arm and therefore, there must be resistance to this movement. As I said above, the valve is almost trying to stop the driver from changing to a new temperature, or at least not quickly.
Maybe it's just a quirky system but it seems odd that when the driver tries to make the heater colder, the thermostat is tring to keep the valve in the hot position. It is definitely the thermostat as when viewed with two mirrors as above, you can see something sticking and then jumping sideways as th operating arm starts to move. You would think that when the car is hot and the driver selects cold, then the heater would be trying to go cold, not trying to stay hot !
Maybe it is like this: Car is hot. Thermostat keeps it that way. Driver selects a bit less hot. Thermostat adjusts to new temperature settin (taking three minutes to do so) and then maintains new temperature. As such, sudden large changes coukd not be accomodated. That's it ! That's the only answer. ..... A sudden flash of inspiration !!.......Then again, perhaps I'm totally wrong ! What do you think ?
Oh... and thanks once again for answering, it has inspired a possible answer. Like I saiod, e-mail or forum post me any specific heater stuff.
By the way, all of this is totally irrelevant for '98 MY onwards which used an electronic stepper motor to change the heater temperature valve !
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