mpcv2000

iTrader: (1)

Hello.
I have a LT1 with a 1995 PCM.
I'm replacing the single speed fan set up I have right now for a Ford Taurus V6 2-Speed fan.

Comming from the PCM I'm using the Dark Green #A11 wire to ground the relay for the fan to start at around 226 Deg. ( factory setting I think ).

There is a Dark Blue comming from the PCM #A10 that should start the 2nd fan at about 235 deg. can I add a relay and and use the Dark Blue wire to ground the 2nd relay ?

I just want to make sure the fan will not get twice 12 Volt ( 12 V on "low" and "high" speed at the same time ) when it switchs from relay #1 to relay #2 because the fan will burn ( I think ) .

Thanks.

Martin.

mpcv2000

iTrader: (1)

I have to bump this because I haven't figure it out yet.

shbox

The question would be how does the Taurus fan achieve 2 speeds? Does it have one wire for low and another for high? If so, are the wires energized separately for low and high? The right relay setup would work for that. A schematic of it's orginal application would be helpful.

The way the tandem LT1 fans work is that the fans run in series for low speed and in parallel for high speed.

mpcv2000

iTrader: (1)

Exactly. There is 3 wires. 1 ground , 1 low speed and one high speed.
I hooked up a battery to each one of them and it's working.

I just cannot figure out if the LT1 PCM will shut fan # 1 before switching to #2 if it's the case , I'll put 2 relay and I'll be ok.

I just want to make sure the PCM will not shoot twice 12Volts on low and high speed at the same time.

I don't want to burn the fan ( bought new for $170.00 cdn ) or burn the PCM.

Thanks for your help.

Martin.

cadsmobile

This can be done. This is what I did on my 240 Volvo with a 93 LT1 but I used the PCM fan signals rather than a thermoswitch:
http://www.rx7club.com/showthread.php?t=839089
It's not on the road yet so it hasn't been really tested yet but should work fine.

mpcv2000

iTrader: (1)

I'll read that thread ( link ) tonight.

Thanks.

shbox

Are you using a fuse/relay panel from your donor LT1 car (if so, what was the donor car and how many relays did it have?)?

The PCM puts out a ground to operate the factory relays. When high speed mode is needed, it additionally grounds the dark blue PCM wire. So, you end up with all relays operated. All you need to do is reconfigure the relay wiring so that when the high speed relay is triggered, that the low speed relay kicks off.

mpcv2000

iTrader: (1)

No I don't

I knew about that too ( read it on your site . )


This is exactly what I want to do , I thought it was the solution but I'm unable to find or draw myself a schematic for it.

The link on the RX7 forum is my 2nd option but I rather use the LT1 PCM to manage the on/off fans operation.

I'm getting close to find a solution to my fan issue.

I thought you were the one who can guide me with my Ford Taurus 2-Speed fan project.






.

shbox

I can probably come up with a schematic based on the 3 relay system the factory uses. You'll just have to create your own relay panel to accomodate them. Let me know if you think that will help.

mpcv2000

iTrader: (1)

I'll donate on your web site if you can provide me that information.
Does it sound Ok ?

I'm using your site a lot for all kind of tech infos , a donation will be well worth it.

shbox

I think this will work for you. Only 2 relays...

http://shbox.com/1/fan_schematic_two_spd.jpg

mpcv2000

iTrader: (1)

I've never seen that schematic on your web site before.

So that way if the 335 Dk Grn & 473 Dk Blu gets grounded at the same time the 335 Dk Grn will become a "open" circuit ( turn off the low speed fan wire) ?
If it's the case this will do the trick for me.

shbox

I just now custom made the schematic for you. Looping the low speed fan power through the other relay's normal contacts enables it to kill the power to the low speed fan when the high speed relay kicks on. The PCM control wires (green and blue) stay grounded (you can't do anything about that and it does not really matter).

mpcv2000

iTrader: (1)

You are the man.
I'll try to install that this comming Thursday.
I have to share time between my car and my girl friend.I'm sure a lot of you understand that.


Thanks.

mpcv2000

iTrader: (1)

oh... Small donation has been given to help you keep your web page up.

shbox