Why is my Fan so Cold?

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yosini
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Why is my Fan so Cold?

Post by yosini » Mon Nov 18, 2019 9:09 pm

It's that time of year again.....So, the heater blows nice and strong but whatever position the heater knob is at and however hot the engine is I just get cold air. All the pipes seem to get hot going in and out of the bulkhead (but that could be heat bleed I guess) but I don't want to start taking the dash to bits if it's a simple to fix problem so I thought I'd ask here first. My thoughts were that the heater knob is doing nothing and is stuck in cold position, but it has resistance and sounds like it is moving something, airlock, maybe but the system seems to be flowing water ok, I haven't tried filling the system with the front raised up though. Does anyone have any clever ideas? At least the car keeps good temperature, even if the driver is freezing....

Cheers

Joe


1963 Daimler Dart
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1972 Maserati Indy
1972 TVR Vixen
1974 Lotus Elan +2 130/5
1977 Scimitar SE6A
1980 VW T25 Campervan
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Roger Pennington
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Why is my Fan so Cold?

Post by Roger Pennington » Mon Nov 18, 2019 10:01 pm

A quick question to start with - which vents are you checking? A common misunderstanding is to expect warm air out of some/all of the eyeball vents. That'll never happen, they're fresh air vents, and only ever blow cold.

The only vents which should blow hot are the two demister vents in the top of the dash, and the two oblong vents in the footwells.

So, if the air direction lever is in the correct position, and the air from the outlets is still cold, there are a few possibilities:

The flaps in the heater box have foam on them to seal them, but that can fall off and clog the matrix. Or the flaps may simply not be working.

The matrix itself may be blocked internally

Someone in the past may have flushed it with excessive pressure, causing the inlet water to "short circuit" straight to the outlet (they're at the same end)

If you've got good airflow, that's half the battle!


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Why is my Fan so Cold?

Post by scimjim » Mon Nov 18, 2019 10:04 pm

Take the side panel off to see if the lever is actually moving a heater flap first. The only other thing I can think of, is that the matrix has been over pressurised and blown out the separator plate, so the hot coolant is going in and straight out without going through the matrix?


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Why is my Fan so Cold?

Post by mark rudder » Tue Nov 19, 2019 1:05 am

Joe, that's a impressive list of toys.
As Jim said check the flap moves, I have the same problem.
Jim, silly question, where's the side panel?


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Why is my Fan so Cold?

Post by scimjim » Tue Nov 19, 2019 6:12 am

mark rudder wrote:
Tue Nov 19, 2019 1:05 am
Jim, silly question, where's the side panel?
by your LH knee on a RHD car - just remembered that it’s not a quick job on a 6 series like it is on a 5a though!


Jim King

SECURE DRY STORAGE FOR YOUR SCIMITAR

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
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Why is my Fan so Cold?

Post by ard126k » Tue Nov 19, 2019 5:00 pm

If you take the plastic face plate off the footwell vent you can insert a finger and feel if the flap is moving. I had a jammed one so although the lever felt more or less ok it wasn't moving anything.
Alex.


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Why is my Fan so Cold?

Post by yosini » Tue Nov 19, 2019 9:40 pm

OK, so a bit of an update after being sat in 25 minutes of gridlock traffic to move 100 metres this morning (you've gotta love roadworks and three way lights filtering during rush hour). If the flaps are on screen and cold I can feel a reasonable (not fast) movement of cold air from the screen vents, if on screen and hot there is a very very marginal increase in temperature, it is hardly noticeable but it is certainly a bit warmer. This testing occupied me for about 10 minutes in the gridlock before O decided to try the footwell vent. Now this is where it gets confusing, or maybe not, if the flaps are set to footwell and cold, I get cold air moving quite fast out of the footwell vents, but when the heater flap is flicked up to war, I actually get hot air out in the footwells! So, I guess that means my flaps are working, but why such a difference to the footwells and no difference to the windscreen.

Curiouser and curiouser....

At least the car keeps good temperature and I can now have warm feet.

Mark - thanks - glad you appreciated the list, they all work too apart from one of the T25s....

Cheers

Joe


1963 Daimler Dart
1968 Jensen Interceptor
1969 Rover P6 3500
1972 Maserati Indy
1972 TVR Vixen
1974 Lotus Elan +2 130/5
1977 Scimitar SE6A
1980 VW T25 Campervan
1981 VW T25 Campervan
1988 Toyota Hilux pickup
1996 TVR Cerbera AJP 4.2
1999 Subaru Impreza Turbo Sportswagon
2003 Smart Roadster

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Why is my Fan so Cold?

Post by mark rudder » Wed Nov 20, 2019 3:15 am

Joe, just be sure the flaps work before coming in to land!


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Why is my Fan so Cold?

Post by peter freeman » Wed Nov 20, 2019 8:42 am

When I had a 6A during the winter I fitted a fan unit in the passenger foot well ( high up so it did not get in the way ) and plumbed it into the heating pipes so that it recirculated the air in the cab and did not draw air from outside - made a big difference to the heat in the cab.



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Why is my Fan so Cold?

Post by Oldconn » Wed Nov 20, 2019 9:38 am

Joe, that sounds exactly like my 6A. Peter, great minds think alike! I am in the process of fitting a small auxiliary fan unit, water-heated, in my footwell. How did you plumb yours in?


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Why is my Fan so Cold?

Post by peter freeman » Wed Nov 20, 2019 12:04 pm

I did not plumb it in to the water just blanked off the cold air to the heater and then used cab air to supply the heater - via the fan



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Why is my Fan so Cold?

Post by ard126k » Thu Nov 21, 2019 8:43 pm

Joe
Don't take offence, but you know that the top position on the distribution lever isn't the demist? It shuts off all the air outlets, it's the middle one that's demist.
Sorry for mentioning the bleeding obvious!!
Alex.


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yosini
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Why is my Fan so Cold?

Post by yosini » Fri Nov 22, 2019 11:42 pm

Hi Alex,

No offense taken, and thanks for pointing that out as I actually wasn't aware of that! Strangely the other day when I had lots of stuck in traffic time to kill I did try the lever in the middle position briefly and thought that it seemed to be warmer at the demist area but then quickly dismissed it thinking that would just be daft....

Looking forward to the next frosty morning now!

Thanks all

Joe


1963 Daimler Dart
1968 Jensen Interceptor
1969 Rover P6 3500
1972 Maserati Indy
1972 TVR Vixen
1974 Lotus Elan +2 130/5
1977 Scimitar SE6A
1980 VW T25 Campervan
1981 VW T25 Campervan
1988 Toyota Hilux pickup
1996 TVR Cerbera AJP 4.2
1999 Subaru Impreza Turbo Sportswagon
2003 Smart Roadster

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Why is my Fan so Cold?

Post by scimjim » Sat Nov 23, 2019 9:22 am



Jim King

SECURE DRY STORAGE FOR YOUR SCIMITAR

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), 1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS

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Why is my Fan so Cold?

Post by ard126k » Sat Nov 23, 2019 10:11 am

Daft it is! Let us know how you get on. It took me a while to work it out myself, wonder why Ford (I think the panel's a Ford part?) decided that a second arrow would be clearer than a circle or even a square?


1971 SE5 1977 SE6 1982 GTC

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