www.gt4dc.co.uk
Maintain, Modify and DRIVE your GT-Four


It is currently Fri Mar 29, 2024 12:32 pm




Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next
Author Message
PostPosted: Sun Jan 20, 2013 8:12 pm 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
Hi Chaps!

looking for some assistance regarding a st165 cooling fan diagram..

The stock system runs a twin speed set-up, as shown in the diagram, im looking to alter it a little to suit my cars current set-up!

In a nutshell the stock system runs two fans, one rear of main cooling rad and one in the front blowing onto the A/C condenser.
The stock Toyota fans are super efficient at moving lots of air, maybe a big power drain, but very good at their job.. so good i have removed them both due to lack of space!
I have also removed the A/C system and condenser but fitted another after market fan at the front, Still two fans total.
When the engine water temps hit 85', from memory, BOTH fans come on but at the lower speed meaning the water temps carry on rising to around 90' but never get any higher.. This however means the fans never switch off until sufficient air is passing through at speed.

I want to ditch the lower speed in favour of the higher fan speed, as used when the A/C system pressure got high or cooling temps got VERY high.

I suspect on the lower speed the fans are seeing a lower voltage and on the higher speed the full 12-14v!?
I can't see any resistor pack, like that employed on the fuel pump system, so wondered wheather having two relays in series would add enough resistance to slow the fans?

I have attached the diagram and would like some others to take a look and offer any advice of loosing the low speed setting but want to keep both the fans in the system..

Image

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
PostPosted: Mon Jan 21, 2013 1:02 pm 
Offline
Club Staff
User avatar

Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
Hi Steve,

Low speed operation is down to both fans being run in series through ac relays 2 and 3

The inelegant solution would be to add even more relays in taking the existing fan wires as the relay coil drive and wiring the fans directly to 12V through the new contacts

I've been trying to see how to reconfigure the current setup to do what you want but the solution elides me so far. I might have to get a pen out.....


Top
 Profile  
 
PostPosted: Mon Jan 21, 2013 1:46 pm 
Offline
Club Staff
User avatar

Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
I give up

I can make it work but some amount of rewiring would be required - I'll draw some diagrams tonight

The basics are this if anyone else can see a way to work it out

Operation is controlled by 2 signals from the ac amplifier - the L-B wire and the B-W wire

L-B is the "emergency" signal. Normally this will be grounded in the AC amp and fans will be driven from the B-W wire
Disconnecting the L-B wire from ground - either when the ac amp sees high temps or when the rad overpressure switch opens - will switch on both fans at full speed

B-W is the normal operation signal. When it is grounded both fans will run at half speed.otherwise the fans are off


What you need to do is intercept the L-B wire with another normally closed relay contact which is controlled by the B-W signal but I don't see a way of doing this with what is in place currently


Top
 Profile  
 
PostPosted: Mon Jan 21, 2013 6:24 pm 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
How about If you remove a/c relay no 3, Jumper pins 2&3 with a bridge wire
Then on relay a/c no2 ether cut or remove wire from pin 3
Or maybe remove a/c relay no3 and move wire no3 pin to pin 4?

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
PostPosted: Mon Jan 21, 2013 7:36 pm 
Offline
Club Staff
User avatar

Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
The first option will always run the ac fan at full speed when the ignition is on unless it gets hot when it will turn the fan off

Option 2 will go bang when it gets hot as you'll short the battery through relay 1

It is an odd setup


Top
 Profile  
 
PostPosted: Mon Jan 21, 2013 8:11 pm 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
two_OH_five wrote:
The first option will always run the ac fan at full speed when the ignition is on unless it gets hot when it will turn the fan off

Option 2 will go bang when it gets hot as you'll short the battery through relay 1

It is an odd setup


Arse!

would be so nice to be able to 'just' pull a relay and jumper some pins and forget all about it! :(

I wonder if my two replacement fans have a higher or lower resistance to the Toyota fans meaning they are running faster or slower?
im guessing they may have a lower resistance?

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
PostPosted: Mon Jan 21, 2013 8:13 pm 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
Im guessing Toyota run this set-up to avoid the need of having a BIG resistor on the fans, as per Vauxhall Saab etc..
The Resistors DO fail, certainly not a word Toyota have built their reputation on, unless its a rubber foot mat ;)

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
PostPosted: Wed Jan 30, 2013 10:22 pm 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
Did you ever get around to taking another look at this?

TIA

Steve

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
PostPosted: Wed Jan 30, 2013 10:47 pm 
Offline
Club Staff
User avatar

Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
Hi Steve,
Yes I did but I was hoping that someone else might chime in...then I plain forgot :oops:

I really can't see a way of reconfiguring the circuit by just making a few tweaks. Best I can see is to cut in another relay

I'll knock up a pic or two


Top
 Profile  
 
PostPosted: Wed Jan 30, 2013 11:16 pm 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
Many thanks :)

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
PostPosted: Wed Jan 30, 2013 11:46 pm 
Offline
Group B
User avatar

Joined: Sat Sep 02, 2006 3:13 pm
Posts: 3679
Location: Bournemouth
Car Model: None
AAARRRRGGGHHHH. Just typed a long reply and it's gone. Oh well, here goes again.

Current operation.

Idle. RL1 & 2 (operated together) pulled in via 'high pressure switch' by output (4) going low. RL3 dropped out.

Slow. RL3 pulled in, switching the 2 fans in series via the RL2 N/O contact (currently pulled in)

Fast. RL1 & 2 dropped out. Rad fan driven by RL1 N/C contact and condensor fan driven by RL2 N/C contact. State of RL3 irrelevant as disconnected by RL2 N/O contact.

I see 2 easyish options:

1. If the 'temperature sensor for fan control' is a Normally closed (closed = cold, open = hot) switch type as used in 185 / 205 then use this to switch RL1 & 2 directly. - Cut the wires to this switch. Link together the 2 from the 'fan control amplifier' so it thinks the rad is cool. Cut one wire to the 'high pressure switch' and insert the newly liberated temperature switch in this line.

2. Remove RL3. Buy an aftermarket changeover or normally closed relay (or get another or RL1 type). Wire the coil of the new relay in place of the coil of RL3. Cut one wire to the 'high pressure switch' and insert the normally closed contact of the new relay. - When the unit drives RL3 (for slow speed) it now drops out RL1 & 2 and drives both fans flat out.

_________________
If at first you don't suck seed, try drier grain.

Image


Top
 Profile  
 
PostPosted: Thu Jan 31, 2013 12:31 am 
Offline
Club Staff
User avatar

Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
Here you go
Image

I think you can do this with a little bit of splicing and dicing to re-use the existing socket that the relay is unplugged from if you can source another Fan Relay 1
Then you just need to cut the existing contact wires and splice them in


Top
 Profile  
 
PostPosted: Fri Feb 01, 2013 9:25 am 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
Thanks for your input guys, much appreciated :)

two_OH_five- Is that diagram, with the removed relay, to accompany Nibbles work around?

Again, thanks

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
PostPosted: Fri Feb 01, 2013 12:27 pm 
Offline
Club Staff
User avatar

Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
I think it's option 2 from what Chris posted. I took too long committing my artistic talent to "paper" and he snuck in :lol:


Top
 Profile  
 
PostPosted: Wed Apr 17, 2013 10:14 pm 
Offline
Group N
User avatar

Joined: Sun Oct 02, 2005 6:48 pm
Posts: 270
Car Model: ST165
Nibbles wrote:
1. If the 'temperature sensor for fan control' is a Normally closed (closed = cold, open = hot) switch type as used in 185 / 205 then use this to switch RL1 & 2 directly. - Cut the wires to this switch. Link together the 2 from the 'fan control amplifier' so it thinks the rad is cool. Cut one wire to the 'high pressure switch' and insert the newly liberated temperature switch in this line.




Hi Chris, This is next on my list to tackle..
im after a little clarification on the above work around.

Can you explain what you mean by "Link together the 2 from the 'fan control amplifier' " do you mean pin2 on the Amplifier?
Little confused regarding "insert the newly liberated temperature switch in this line" as to me it looks like it is already in the same line as high pressure switch?

cheers

_________________
Steve Gillies
ST-165 88 UK

www.GT4-Play.co.uk


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next


Who is online

Users browsing this forum: No registered users and 26 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group