[W126 Coupe] Phoenix Relay Set-Up

[Dick Spellman]

Hi Jim,

I've attached a jpg image of the 12 volt, 10 amp rated relay I use with 
a map of terminals to wiring.  

For purposes of understanding what you are creating....you are 
effectively energizing the relay coil when the compressor kicks on and 
this results in the Normally Open to Common circuit on the relay 
switching to CLOSED allowing the positive side of the fan circuit to be 
completed hence, the fan kicks ON.  The trigger for energizing the relay 
is off of the tapped lead (1 of 3) attached to the back of the Denso 
compressor.  You have to tap the correct wire obviously.

So, rather than wait for the fan pressure switch on the receiver/dryer 
to call for added cooling sans the aux fan, you have added cooling at 
all times so long as the ac compressor is on.

I will attach an image of the relay wired in place in a second email soon.

The aux fan for other running conditions such as the 110C manifold 
sensor continues to behave as before when AC is not in use.

Regards,

Dick

 jralex at ix.netcom.com wrote:

> Dick, I am interested in the fan wiring info. Send to: jralex at ix.netcom.com. Thanks! J. Alexander

>

> -----Original Message-----

>   

>> From: Dick Spellman <spell.yy at verizon.net>

>> Sent: Jun 19, 2008 3:48 PM

>> To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>

>> Subject: [W126 Coupe] Phoenix Relay Set-Up

>>

>> If anyone is interested,

>>

>> I have photos and mapped the hook-up needed for a Denso compressor to 

>> always run the aux fan circuit so long as AC is selected.  I'm doing the 

>> write-up this weekend for Jonathan and sending him the relay I use for 

>> this purpose as a thank you for all his techy and parts support.  This 

>> is my third hot weather set-up of this kind.  It was originally 

>> prescribed by Stu Ritter and I have just given it the nick-name Phoenix 

>> because it's always steammy there in the summer months.

>>

>> Amazingly, the coolant temp never leaves the top of the 80C indicator on 

>> these M103 motors with this set-up and this naturally assumes all other 

>> components are in good service order like visco, tstat, radiator, water 

>> pump, belt tension and so on.

>>

>> Take care and stay cool.

>>

>> Dick


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