As a matter of observation (without even considering science) I have never seen condensation on the outside of a cup of hot tea but I have seen condensation on the outside of a cold glass of beer..
Not an appropriate analogy
On the other hand all aircon systems condense water out of humid air, just like that cold beer glass, that freezing cold element is the evaporator and part of the effect is to remove humidity from the air, that is why drains for the condensed water are important..
Much better. One merely has to examine a home air conditioner, a window, wall, or central unit. They do not produce condensation in the UK? (Of our 4 months of annual mogging in Europe, we were never there for the summer months!)
I can assure you that after 10 years of use there is no rust on the heater control quadrant (behind the knob on the dash). If any water ever got there I would be looking for leaks higher up.
Gambalunga, my thoughts on this subject (almost two decades ago) address early overseas AC Roadsters. The wide spread rusting control complaints came from that crowd (the Roadster forum). Don't shoot this messenger.
I merely followed LOGIC and the valve operated cabin heating systems from Morgans from the later 1950s to 2004. It is obviously unwise to run AC cooled air through a heated place adjacent and above a constantly hyper-heated heater matrix without a shut-off valve. If you think that has no effect, so be it. I am not a retailer. I haven't advertised or a accepted advertising in 30 years.
It is people like yourself, with much later Morgans, who have told me the system never changed..which astounds me.
Lastly, overseas stock Roadsters had AC long before they became common anywhere else. Much more experience I imagine. And the UK has very different weather. Much damper and cooler ambient conditions. Australia and the southern US weather are quite different from the UK. So the fault will express itself differently. As I said, the simple fix never fails with owners in those parts of the world. Nothing brilliant in any of this. Merely common sense. It is also my observation that common sense is a much lower priority for auto manufacturers than government regulations. There is no laws I know, worldwide, the require the latter any more.
Now to forget about aircon for a moment and discuss hot air entering the cabin
All trad owners have problems with that. A few obvious factors come to mind.
1. The
cutoff of the coolant into the heater matrix is inadequately handled by the traditional valve. I changed mine to an electrically operated solenoid shut-off. That worked.
2. The
constant flow of air into the heater system from the engine bay, is AS YOU SAY, a problem. It can be cured in many ways. The simplest is to block that inflow with a piece of cardboard used as an air dam. (tedious) I found the solenoid valve sufficient..that being said I have heat reducing ceramic coated manifolds and down pipes which muchly reduce engine bay heat.
3. The cabin heat is effected, (again muchly) by
un-insulated firewalls and too thin insulation of the gearbox cover. (the gearbox area is designed in such a way that it traps hot engine air flowing under the car). I swapped out my firewall carpeting for insulated carpeting and though I have the same gearbox insulation as you do, I insisted on 1/2" rather than 1/4" padding on my gearbox leather. Unlike my earlier Morgans, we can rest our legs against the gearbox regardless of weather on the hottest day.
....ideally, it should be a solenoid valve linked to the dashboard heater control system.
Smart man.
I imagined a solenoid valve connected to the control system, though I never bother to think of the details for that. Turn on the heat, and the hot coolant flow would be opened to the matrix again.
I am somewhat inspired to experiment with a valve although I have to say that my experience is that blocking hot engine bay air from entering the top of the airbox makes a big difference.[/quote]
No need to do much to see if the idea works. Merely join the matrix in flow to the outflow. with a cheap joining pipe of the right size. Your matrix will drain on the floor, but you can add the small bit of coolant lost to the system when you run it to stock. A cheap plastic joiner will cost you about 1 pound on Amazon.uk.co. Be great if you could test the relative AC effect and humidity, before and after. IN any event, assuming you DO have the same system as the one's I have seen, it is hard to argue with success.
Good luck.
gmg
