Legal blowers

[Vee8ight]

I have an interesting problem.

If I stick to the speed limits, I get hot or cold air blowers as I choose, however if I travel any faster, I get cold air in the winter and hot air in the summer.

I realise that it's getting forced through from the ducts at the front, so my question is, has anyone got photos or a schematic of the ducting so I can formulate a solution without using a tennis ball

Darren

[Luckyone]

Luckyone said:

Air con/ cold air not very cold, & or, hot air coming out of the vents with the fans off, & or, Heating not very hot:

This only applies to, I think pre 2000 cars, it’s actually a TVR approved fix that you can ask you dealer to do. (I think they got it right on the later cars) Thanks to Andy @ APM for the info!

The ambient air intake for hot air is the space in wing above N/S front wheel. This is fed from the different holes in the front of the car, which means as you go faster the cold air is forced by ram effect through the heater & into the cabin. There is a one way valve but it opens with the air pressure, it's to stop the cold air blowing out of the hot intake. (the same thing happens the otherway round) You can hear it shut when you turn on the cold fan, you can also hear it flapping about at certain speeds as the ram air pressure is just enough to open it. (if you can't hear it it could be stuck) The trouble is the ram pressure at motorway speeds is more than the cold air pressure from the fan & this valve is forced open mixing hot air with your air con chilled air.
The fix is TVR approved & there is a kit you can order from the parts dep. to do it, but I did it my self. Basically you change he heating to a recirculation system. You have to block off the inside of the wing, I used cardboard & expanding foam (but had to shave my arms after as it got stuck in the hair!) it’s tricky as you have to go in through the hole for changing the bulbs – much easer if you still have the old style lights & can take the unit out. Second bit is easier, inside the passenger foot well there is removable panel at the bottom that covers the EUC, take it out & cut a largish hole in the flat bit you can’t see so the hole faces up. Then take the carpet off the inner wing to see what you are doing & cut a hole in the upper forward part of it, that would be covered by the panel, then put it all back (using some spray carpet glue). Now the air for the heater will through from the holes you cut .
Result being the air going into the heater is the already warmish air from inside the car so it can really warm up this time of year, rather than try to warm the sub zero out side air. Also when you turn off the hot fan there is no pressure at any speed so the cold air stays cold in the summer.

I wrote this back in 04, I’m also going to add manual control to the cold air flap so I can force it open or shut…

Have a look at my rebuild thread there are some pics of the cold air box taken out there.

[Luckyone]

Here you go with pics:

Luckyone said:

This is how it looks if you stand on your head in the footwell, so the poor cutting doesn't show...


This is what the kick pannel looks like removed.



This is the hole cut in the inner wing.



I used car washing sponges & expanding foam to seal the inner wing. It works well till I get to 60 ish then the cold air pressure opens the cold valve & leeks cold into the mix. How ever I find in the summer there is a lack of cold air flow... So I was thinking of fitting an extra fan for that & a control on the cold air valve for the winter.

Hence my decision to put a manual control on the cold flap. Fan worked a treat, but do see my rebuild thread for even more...

[FUBAR]

Sounds familiar. My passenger side vent. Lows hot air when I put the air on on. Been told that probably the flap (assume the one you mentioned) in the heater matrix is probably jammed open/closed (?), but would mean a dash out to get it sorted. So I just tell mrs Fubes to close off her vent and stop moaning

[Vee8ight]

Thanks Luckyone, that helps a lot. Have you got pics of your fan mods please? I've seen your cold air box pics and the hole that you filled too! I've got that footwell draught, but will leave till winter
I was thinking of cutting a hole in the front of the wheel arch liner to duct air to the brakes and therefore getting rid of the ram effect for the interior fans. What do you think?

[Luckyone]

Vee8ight said:

Thanks Luckyone, that helps a lot. Have you got pics of your fan mods please? I've seen your cold air box pics and the hole that you filled too! I've got that footwell draught, but will leave till winter
I was thinking of cutting a hole in the front of the wheel arch liner to duct air to the brakes and therefore getting rid of the ram effect for the interior fans. What do you think?

I made some ducts to take the air directly to the discs:









Note they are old pics from before my rebuild!



The issues with flappy flaps continued after that. But the whole front end is one open void so the air entering the main rad cooling hole in the front still pressurise that whole void, with way I have those cooling pipes sealed in it’s still pressurised. If you just cut some holes it would reduce the pressure (from the ram air effect) in the inner wings & the whole front end, but that would affect the amount of air going through the radiator to cool the engine. You could try to seal off the radiator portion of the front end void so it stayed at a higher pressure, then cutting your holes so the pressure in the inner wings was reduced, giving the fans a chance to hold the flaps shut. (Assuming you have those cut outs next to the indicator, not all do)

I want to keep the higher pressure in the inner wing to help the cold air fan, hopefully the extra sealing off I mentioned in my rebuld thread will direct all that air where it’s meant to go. Then for winter when I don’t want cold air getting to the hot mix I’ll get round to making the flaps manual controls.


The extra fan is fitted here: (is that what you meant by fan mods?)





It works very well, but is also very noisy even by Cerb standards, so I was hoping to make the most of the standard set up before having to switch that fan on. I got that fan here if you want one.

[Luckyone]

FUBAR said:

Sounds familiar. My passenger side vent. Lows hot air when I put the air on on. Been told that probably the flap (assume the one you mentioned) in the heater matrix is probably jammed open/closed (?), but would mean a dash out to get it sorted. So I just tell mrs Fubes to close off her vent and stop moaning

There is basically just a big box in the middle of the car under the dash that all the pipes to feed the hot / cold vents come from. The feeds into that box are the cold pipe (in the drivers side foot well, the one I put the fan in in those pics above) & the hot feed in the passenger side upper foot well. So if you don’t have that recalculation mod I explained above the hot air starts to get forced in to the big box as you go faster.

Mrs Fubes passenger air vent outlet that is fed from that box is closest to the hot inlet so is the first to feel the effect of the hot air leaking in.

It’s probably unlikely that the one way flaps/ valves on the hot air feed is jammed, but it’s quite easy to check you just need to take the big pipe off the feed to the air box up in the top of the passenger foot well & give the flap a poke. Or more easily with the engine not running turn on the hot fan off & on & listen for the metallic clink of the flap opening & shutting. It’s just the air pressure that opens it & gravity that shuts it. As long as your flap is flapping freely it’s worth getting that hot air recirculation mod done, as it helps both keeping you warm in the winter & cool in the summer, along with a happy mrs Fubes

No need to touch the dash for any of it

[FUBAR]

Excellent Andy thanks. I'll have a poke about with Mrs Fubes' flap tonight to see if I can stop the moaning

[Luckyone]

FUBAR said:

Excellent Andy thanks. I'll have a poke about with Mrs Fubes' flap tonight to see if I can stop the moaning

[Jhonno]

FUBAR said:

Excellent Andy thanks. I'll have a poke about with Mrs Fubes' flap tonight to see if I can stop the moaning

[Vee8ight]

FUBAR said:

Excellent Andy thanks. I'll have a poke about with Mrs Fubes' flap tonight to see if I can stop the moaning

And you don't need to touch the dashboard either