Fan speed control Forums

kands · Account Deactivated

Hi all
Ok now I am really fed up with this A/C / Heater fan speed problem....... We only have full speed, not any others....
I have recently bought a new switch (with some dodgy advice Laughing

) only to find that it is not the switch (got one for sale now, brand new shiny chrome jobby Laughing

). I have searched all over the front of the RV and still cannot find anything that looks like a resistor pack. I have looked all around the area where the fan motor is and its housing but so far nothing..... Can any of you kind people please let me know where your resistor pack is located and I can try to search in new places... I would also be happy if you could describe what yours looks like so that I know what to look for Rolling Eyes

I have a Chevy P30 chassis, if that makes any difference.........

Looking forward to your replies guys...

Keith

MandyandDave · Moderator

Hi Keith, If you have no luck finding it, I will have a poke around at mansfield meet to track the little beggar down! Wink

kands · Account Deactivated

Hi Dave
Thanks for the offer mate, I'll bring a torch and a long stick mate....

Keith

teemyob

Hello Keith,

What is it you are actually attemting to control the fan one?

The Habicon Heatpump Fan?
Is it 12/24/240v?
Where are you wanting to put this Fan Speed Controller, near / on it, the dash?

Le me know see if I can help

Trev

kands · Account Deactivated

Hi Trev
The fan is the factory fitted dash fan that blows air from the dash outlets or diverts to the floor to feet level. It has four speeds (or rather it did...) and now only the fast speed is working. I have chased out the wiring amongst the rats nest behind the dash, and I find the speed selector switch (changed for a new one...), a relay (5 pin, 2 coil connections and one input wire with two output wires individually selected by the action of the relay), and the fan motor itself with two wires connected to it.
The switch is fitted into the A/C and heater control assembly in the dash.
I am thinking of trying to obtain a new relay and if that doesn't work then having the motor tested to see if the windings are ok.... May do a quick check on the windings myself in the meantime.
Any suggestions will be very well appreciated as I am very confused about this fault now and cannot see the wood for the trees... The Chevy manual says that if the fan does not run on all speeds take the RV to an electrical shop and have them sort it out Rolling Eyes

Helpful or what???? Laughing

Keith

teemyob

Hello Keith,

Considering what you have said, the problem I think points in the direction of the windings more than anything.

Yes the switch sounds like an obvious or moreover Easier trial and error route to take.

Do not rush out for the relay until you have checked the windings. Assuming you have not meddled with anything recently. Check all the obvious wiring points for good contact. I recently fixed a newish Renault van Fan, simply by cleaninng the bullet connecter under the bonnet that had become soaked by water ingress and rusted.

Another thing to check is the motor shaft/bearings. Does it work on a lower speed after setting on 4 then moving to 3? Or am I stating the obvious?

I will speak to a really techy bloke I know tommorow see what he comes up with.

Trev

artona · Moderator

Hi Keith

Since the offending part is putting through maximum power could you simply put another one in the system and use that to regulate it.

stew

kands · Account Deactivated

Hi Trev
Thanks for this help mate... I am inclined to suspect that the motor is the cause because I pulled the relay apart and it seemed to be in good condition, with clean contacts etc, and when the switch is put into the full position the relay switches over and the fan runs.
What I don't understand is how the motor works??? It only has two wires going to it, and these are from the aforementioned relay, so I would have assumed that the voltage control would have to be done elsewhere???
If someone could kindly explain how I get four speeds from this configuration I would be grateful, I am beginning to think I am having a very senior moment here....
Hi Stewart, I had considered using a potentiometer in the power feed to the fan to regulate the speed, but concluded that it was for whimps Laughing

I would rather solve the problem correctly as I hate bodge jobs mate and so far we have not bodged anything on the RV, so I don't want to start now. Expensive way to go sometimes but it is the best in the long run.....

Thanks both for your input and I look forward to receiving some more...

Keith

sallytrafic · Southern Rally Co-ordinator

Assuming the motor has an earth/chassis return ie there are really three wires connecting it two from the relay and the return. That gives 4 combinations if we call them wire 1 (W1) and wire 2 (W2)

W1 =off W2 =off
W1 =on W2 =off
W1 =off W2 =on
W1 =on W2 =on

Now from here I can't say how this actually gives you your 4 speeds but that shows that the control system is capable of it.

Regards Frank