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Heater Blower

Richard Pottle

Richard Pottle

PCGB Member
Member
Technical question for you here - does anyone know how many cubic feet per minute or cubic metres per minute the capacity of the 3.2 heater blower is?

The reason I am asking is that my car has a 993 engine fitted and the original heater blower system is too big to fit in the engine compartment and I am researching other smaller 'makeshift' blowers that would fit in anticipation of the cold winter and ice inside the cockpit!! [:mad:]

Many thanks in advance!!

Richard
 
I use a small, boat based one, that is cylindrical, and fits inside the hot air pipe in the engine bay (no room for the real one). That, along with the engine fan itself, and the two footwell blowers, makes the cabin nice and warm.

Mind you, I have the air-con on all year round, and tend to walk around in short-sleeved shirts all winter, so maybe I am not the best person to answer this !
 
Thanks for the reply John. I've just purchased an inline marine compact blower for £25 - could be one of the cheapest brand new modifications I do to my motor. Hopefully it will fit in the engine bay....
 
Andrew,
You don't say which blower !! You've actually got 4, a cold air blower mounted in the front luggage compartment and controlled from the dash slider control, 2 footwell blowers which are controlled by the heater control between the front seats (I think they come on at the upper settings 7 onwards) and the main heater blower that is mounted top left of the engine bay. This again is controlled by the heater controls between the seats, it should come on when you switch from 0 to 1 and I think increase in speed accordingly up to 10.

All blowers have a habit of giving up the ghost but they can be stripped and checked over.

HTH
 
And don't forget the fifth blower, the engine fan itself. I know, it's on all the time, but it still adds to the moving hot air.

Seriously, maybe, if all the 3 heater blowers don't work, it could be the control between the seats, and it's wiring. Is there a whirring noise (a small electric motor turning over) from the unit when the control is turned from min to max ? This implies that the unit is getting power, and to an extent working. The fact of the 2 flaps (on the firewall) working can be detected by the fact that the engine fan will push some hot air through the system when open.

Trouble is, these problems are easier to solve in situ, but please don't stop asking the questions.
 
Thanks for your explanation, the fan which seems not to work is the one that is operated on the slider on the top right of the heater control panel. The others all seem to work. any ideas on where to start??

Having now read the owners manual the operation of the heater system has now become a little clearer as it appears to be quite complicated, I think I have been spoilt with climate in recent years!!

Regards


Andrew Symms

FFDDEA76B5484F65AAA4E73BD72B05C0.jpg
 
the fan which seems not to work is the one that is operated on the slider on the top right of the heater control panel.
Click to expand...

Do you mean the sliders on the dashboard ? If so, then this controls fresh air from the outside only. Maybe it's just me that is confused.
 
John

I am sure that its me confussing things, I assumed that the top right slider on the heater controls on the dash, was a fan as it has marks on it like for the speed.

Perhaps we should start the other way aorund, the reason this all came about, I was out last weekend and the screen started to mist up, I tried all sorts of comninations but seem not to be able to get air to blow up on the screen.

With the engine not running I have tried the heater control knob between the seats and can hear the motors operating. Also I can get hot air through.

I don't know if that make any more sense???

Regards


Andrew
 
Ah.

The top 1/2 (? - changes happened about 85/86) sliders are for the fresh air blower. The middle slider is fresh air right - screen, left - footwell, and all points between. The bottom slider is for hot air, and works the same as the middle slider.

Demisting the screen can be a real pain - if it is damp outside, sometimes the hot air blower will blow hot, moist air onto a cold screen, making it worse. Luckily, I have air-con, which drys the air, so that the screen doesn't have a chance to mist up - I have the a/c on all year round.

Does this help ? If in doubt, keep asking.
 
John

Thanks for all the advise it seems like I will just have to use my car when the weather is fine!
I am glad I asked the question before I started taking the dash apart.

The forum is really useful and I am sure I will be back with more questions as problems occur.

Thanks alot.

Andrew Symms
 
Are you near North London I could have a look if you like. It's a simple system, unfortuneately if the dash controlled fan isn't operational then you can't 'blast' the screen with hot air and hence demist it. Try moving the right top lever from left to right in small increments, you might find it will work only at certain positions on the scale.
 
Andrew,
Hi there.. happy warm porsche owner. ?
I could assume that your car is kept outside?
I ask this because the 911 just like a air-cooled VW is dependant on enviroment where it has been parked for previous hours ( does this make sense?) In other words ; if the mtr and heat exchangers are wet & cold ( outside), then the whole system needs to warm-up before the cabin gets dry. This includes the ducts from heat exchanger to cabin.
if the car was dry to start, I doubt there would be a problem.
 
I have experienced two relays going on mine --the only failure on the car(other than routine service items) --and I have owned it new since 1987.Check the relay l/hand side of engine hidden by black plastic shroud.It sounds very much like this part.The footwell blowers can crudely be checked by taking out the carpet and putting 12volts through them.Certainly needed this weather
Regards
David Newton
 

All sorted .... , stupid or what i checked the fuse and was OK but upon
closer inspection the point wasn't making contact so changed the fuse and all
Ok.

Ian

 
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