# Fan speed control



## 88927 (May 10, 2005)

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 :lol: :lol: :lol: ) only to find that it is not the switch (got one for sale now, brand new shiny chrome jobby :lol: ). 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 :roll: :roll: :roll: 
I have a Chevy P30 chassis, if that makes any difference.........

Looking forward to your replies guys...

Keith


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## 88781 (May 9, 2005)

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:


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## 88927 (May 10, 2005)

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

Keith


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## teemyob (Nov 22, 2005)

*The resistor*

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


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## 88927 (May 10, 2005)

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 :roll: :roll: :roll: Helpful or what???? :lol: :lol: 

Keith


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## teemyob (Nov 22, 2005)

*Fannying About*

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


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## artona (Jan 19, 2006)

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


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## 88927 (May 10, 2005)

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 :lol: :lol: :lol: 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


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## sallytrafic (Jan 17, 2006)

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


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## teemyob (Nov 22, 2005)

*Fan*

Hello Keith,

I have not had time to look into your problem in detail.

If the fan is only 2 wires then probaly not the problem, more likely

As the previous poster says with W1 W2 through the relay is correct for a 2 wire fan which would not rule out internal problems with the relay. I am assuming it is the black concealed type.

When you say you have cleaned the contacts, do you mean the contacts that go inot the sockets/connections?

Trev


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## 88927 (May 10, 2005)

Hi both and thanks for your help
The switch "used" to work giving four different speeds, the OFF position is controlled by a separate switch on the unit, unless my memory is giving out and it would seem to make sense to be able to shut down just the fan, so maybe the thing does work as per Franks list....Thereby making it a three speed and off fan. The motor is certainly bolted to the frame but I didn't think to check for a good earth connection..... Next job then....
The relay is a black five pin square plastic bodied unit. I managed to separate the top part from the base and can see a pair of contacts and the coil. I did clean the contact faces and the pins that attach to the base.
I will pull it out and photograph it later to show it better than my description.
Thanks again guys

Keith


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## 88927 (May 10, 2005)

Hi
Just thought I would put on a couple of pictures of the relay to show what it looks like...

The relay is a Hella 4RD 960 388-07
Interestingly since I pulled it apart again I have no fan speeds, so I guess it looks as though the relay is faulty, or I have disturbed some wiring.....

Thanks again guys

Keith


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## 97201 (Jan 7, 2006)

Keith

I can't see any pics.

Ian


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## 97201 (Jan 7, 2006)

Keith

I can't see any pics.

Ian

Edit: 1 has just appeared

Edit: 2nd has just appeared - why is that? I have a very fast comp.


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## 88927 (May 10, 2005)

Hi Ian
They were to big and they got rejected mate, but they are both there now :lol: :lol: :lol: 

Keith


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## LC1962 (Oct 6, 2005)

Keith....just poking about and found this.... http://www.imperialinc.com/items.asp?item=0722400
any good?


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## 88927 (May 10, 2005)

That's the one Linda..... I don't believe it, I have been googling the Hella details for about an hour and come up with nothing, and there you go in about ten minutes :roll: :roll: What would we do without you????
Do you have one of these in stock? If so please ship ASAP and I will send gold by return :lol: :lol: :lol: 

Thanks Linda

Keith


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## LC1962 (Oct 6, 2005)

kands said:


> That's the one Linda..... I don't believe it, I have been googling the Hella details for about an hour and come up with nothing, and there you go in about ten minutes :roll: :roll: What would we do without you????
> Do you have one of these in stock? If so please ship ASAP and I will send gold by return :lol: :lol: :lol:
> 
> Thanks Linda
> ...


I knew I was useful for something :lol: :lol: (and I was using Google too....obviously a "woman's touch" thing  )

I don't believe we have any but I shall set my trusty bloodhound on the trail in the morning....leave it with me :wink:

Oh, and if I do get it, make that 2 bags of gold and a couple of camels :lol: :lol:


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## LC1962 (Oct 6, 2005)

Hi Keith
Further to the above.....I am holding fire on this as I think you got an email from our mutual friend JSW today (he inadvertantly sent it to me first :lol: ) If you don't have any joy I shall get one in for you....keep me posted.
BTW...did my email get through to you OK?

Cheers
Linda


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## 88927 (May 10, 2005)

Hi Linda
Thanks for that. Yes JSW did send an email and I am going to order a relay tomorrow.
Thanks very much JSW, a great help indeed, again, mate... I know that you can see this and I will email you as well....
Regarding your other email Linda... Nah nothing.... Did you send it to the right address :lol: :lol: :lol: because the mail server is a lot less forgiving than the postman :lol: :lol: :lol: Please try again or PM me on here....

Keith


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## LC1962 (Oct 6, 2005)

Hi Keith - I emailed through MHF.. :roll: ..I have a copy in my inbox so will forward it via PM now...shout if you don't get it :? 

Good luck with the relay....shame...I could have done with the camels to keep the grass down till our new lawnmower arrives from the States :lol: :lol: 

I wonder if MHS Rob would lend me his goats?? :lol: :lol: 

PMing now :wink: 

Cheers
Linda


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## olley (May 1, 2005)

Hi Keith, thats a standard change-over-relay, any branch of lucas or similar company should be able to supply.

I bought 2 a few weeks ago when I had trouble with the gas con. about a fiver each.

Going to stick my neck out and say I don't see how that can give you three fan speeds. two spades are for the coil and the other 3 are for the change over, have you tried joining any of the change over wires together?

Olley


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## sallytrafic (Jan 17, 2006)

olley said:


> Going to stick my neck out and say I don't see how that can give you three fan speeds. two spades are for the coil and the other 3 are for the change over, have you tried joining any of the change over wires together?
> 
> Olley


Neither can I now that I have seen the relay because with a single change over you can never get two of the possibilities in the table I drew up earlier. 
Which means a maximum to two speeds.

If it used to work and nothing has changed then its a mystery and I guess there is part of the circuit that hasn't been discovered yet.

Regards Frank


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## 88927 (May 10, 2005)

Hi all
Beats me too.... I have not understood this circuit since day one, as I said previously I don't think there is enough wires / connections to achieve any more than two speeds :roll: :roll: 
From the rats nest that purports to be a wiring loom, it is extremely difficult to see what exactly is going on, and I am completely the wrong shape to get myself into a position suitable to be able to follow the cabling runs. I have discovered that some wiring departs from the loom, behind a piece of the dash which is impossible to get to.... and goes off towards the front bulkhead and I believe it passes through into the front of the engine compartment where the batteries and distribution box are located. It is too dark now to see any more so I will have another go tomorrow but I think I am going to get a new relay anyway.....
I may end up getting an auto electrician in to suss this out as it is beating me and I really want to get it sorted out now.
I will let you all know what I find tomorrow and once again, thanks for the input, ideas and suggestions, they are most welcome.

Keith


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## olley (May 1, 2005)

hi keith, I would have thought Diving under the dash and swimming about would be second nature to sub-mariner. :lol: :lol: 

And after looking under my dash I can tell you that the Rats nest sums it up nicely. 

Olley


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## 88927 (May 10, 2005)

Hi Olley
And there was me hoping that you would say that your, much newer RV would be a real joy in the wiring loom department mate :lol: :lol: :lol: 
Looking at your signature gives me an idea though :lol: :lol: 

Keith


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## olley (May 1, 2005)

kands said:


> Hi Olley
> And there was me hoping that you would say that your, much newer RV would be a real joy in the wiring loom department mate :lol: :lol: :lol:
> Keith


You would think so wouldn't you, huh but you would be absolutely wrong, only good thing is that each wire has a unique number printed all along its length, and if you cross reference this with the wiring diagrams you can find out what its for. But (theirs always a but) this only applies to the winnebago wiring not the workhorse, so after the winnie joins the workhorse wiring your in the dark.  

Olley


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## damondunc (Feb 14, 2006)

*Fan speed control Chevy P30*

Hi Keith,
The way your fan control works is:The 1st 2nd and 3rd speeds are controlled by a resistor pack which is located in one of four places1)under the hood on the passenger side on the side of the heater matrix box(2)again on the heater matrix box but on the front edge or(3) inside the RV on the passenger side under the dash attached to the rearmost edge of the heater motor trunking.(4) on a bracket on the passenger side just to side of the radiator.
If it's in any of the first three places you will see a four or five wire multi plug on a square plug. The resistor pack is normally held on with 2 screws with the resistors inside the trunking, the rush of air inside the trunking keeps the pack cool. When you find it remove it and you will see three spring like resistors one of which may be burnt through or there is a thermal cut out like a bimetallic strip which may be burnt out.
The fast (4th) speed is controlled by the relay and bypasses the resistors completely. As you move the switch from 1 to 2 to 3 it proggresively lessens the resistance in the circuit hence increasing the fan speed. There is a fuse in your main vehicle fusebox 25 amp labelled heater you may have blown this when removing the relay. There may also be seperate fuse for the first three speeds which also controls the fans suspended from your front cupboards.
If you get a problem email me your phone number and I will talk you throgh it.
Cheers duncan.


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## 88927 (May 10, 2005)

Hi duncan
Thanks for the info matey... I have been out with my torch and cannot see this resistor pack anywhere??? I have checked the fuse and it is OK. I have checked for volts at the motor and have +12.5 Volts when the switch is in position 4 (high speed) and about +10.0 Volts in all other positions. The fan motor does not run though... I removed the fan motor and strapped it across the battery and it runs so I guess the motor is ok. I checked the earth and it appears to be ok, I even wired in a replacement earth wire and still no fan even though there is +12 Volts at the input terminal. I am now even more confused and I am going to PM you with my phone number to take you up on your offer. I will not be able to do anything now until tomorrow evening as it is so dark and unfortunately I have to work tomorrow (such is the life of us poor people :lol: :lol: :lol: :lol: )
many thanks for your help/advice and kind offer.

Keith

Just a thought Duncan... Are you anywhere near Retford this weekend? We are going to the First Aid meet and if you are close maybe you could drop in, or even better you could come to the meet, sort out my fans and then go through the quickly assembling queue of other MHFers that will need your help, which will pay for the weekend handsomely :lol: :lol: :lol:


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## Steptoe (Nov 8, 2005)

Hi Keith,

The connundrum of why you have volts at the motor input yet it doesn't run is because somewhere in proper supply cable ( as opposed to the temporary one you rigged up to prove the motor was OK ) is the equivalent of a bad connection which is passing voltage but breaks down as soon as current is drawn.

Not unsimilar to the situation where a dodgy battery terminal will allow ignition lights to come on but fail when starter motor is energised.

Of course in your case you haven't got a bad connection ( or have you :? ) but either the relay has a bad contact in the case of full speed or the elusive resister pack has a burnt connector for the lower speeds.

Sorry I can't offer more specific advice relating to the RV.

Why not organise a 'resister finding' meet with a bottle of wine for the successful contestant


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## 88927 (May 10, 2005)

Hi Ernie
Thanks for the ideas mate.... I think that there is a gremlin living in the rats nest that RV builders call a wiring loom :lol: :lol: :lol: 
I like the idea of a "resistor finding party" :lol: and I have set the wheels in motion as we speak. I am very hopeful that the First Aid meet, this coming weekend, will produce a fix :wink: :wink: 
I will be glad to get to the bottom of this one and I am certain that I will be kicking myself when it does get sorted out, it is bound to be something simple and I have missed it   
Never mind I should be doing a DVD player instal at Retford and if I get really lucky an aerial fitting party at the same time (just depends upon the postie....) :lol: :lol:. That should cheer me up :lol: :lol: 
Thanks again mate

Keith


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