Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Another cooling fan relay problem

My Plus 4 has just had a new radiator fitted (from Williams) and everything looks fine. Running temperature is usually about 90-95 deg C as indicated by the temp gauge and I can hear the cooling fan cutting in and out.

Went out a day or two ago for the first proper drive of the year and did about 150 miles without any problem. Then I spent half an hour in heavy city traffic and the temperature rose to an indicated 120 deg C. The only way to get the temperature down was to turn the heater on full. After running outside the city for a while the temperature came back to normal. No sign of water leaks when I got home. When the engine is just ticking over the fan still operates at about 95deg C.

There are two relays for the fan – marked high and low on the wiring diagrams I found on TM – which I guess relate to fan speed. Is that right? And Is it likely that the high relay has failed? The relays are Tyco 0-1432793-1.

All suggestions gratefully received.

Yes - two relays. It looks like the high speed relay may have failed. Try a substitution, but note that you need a relay with diode protection.

Also check the coolant level when cold.

It wouldn't be the first time a garage has missed a connection off the fan - it maybe worth checking first if you have not already done so.

Dave, Richard
Coolant and fan connections all look OK. Spares available from RS at 2.55 plus free delivery ( no connection with me!) - I will replace both relays and have a spare to be on the safe side.

http://uk.rs-online.com/web/p/products/7826953/?cm_mmc=UK-PPC-_-google-_-3_UK_EN_M_IP_and_E_Broad-_-te_connectivity|non_latching_relays&mkwid=s1dhSYO6W_dc|pcrid|78791998844|pkw|%2B1432793+%2B1|pmt|b|prd|&gclid=CIby5qKn3ssCFQWfGwodW50MFw#

There is a data sheet on this webpage which looks OK to me!

Thanks for your help

Good luck Conrad, Just reread your initial enquiry and noted the fan runs, sorry anno domini catching up.

It comes to us all - I've already got it - that's why I have a mog!

I once spent nearly 2 K trying to cure the overheating on an Alfa only to discover it was a malfunctioning Temp Gauge. get an infra red thermometer (eBay about a tenner) and check the temp on the top hose next time it happens before you spend too much money.

I have the same problem on a 2007 Duratec +4, has an Alloy rad etc but the fan doesn’t seem to kick in at all.

Could it be a relay or is it more likely a connection issue?

Can anyone advise what temp the fan should come on at for both high and low speed options.

Many thanks
Will

[/b]

Originally Posted by flyfisher

I have the same problem on a 2007 Duratec +4, has an Alloy rad etc but the fan doesn’t seem to kick in at all.

Could it be a relay or is it more likely a connection issue?

Can anyone advise what temp the fan should come on at for both high and low speed options.

Many thanks
Will

Just croc clip a test meter on it and find out for yourself maybe, it's what the rest of us do, or if it's beyond your skillset take it to a garage this is unbelievably simple stuff to fault find and rectify tbh.

At around[b] 90 and then 100 to the best of my aging memory has been bandied about.

But I stuck an override switch on my Plus 8 as it gets hot in static traffic I prempt the thermo switches by paralleling the fan switch feed GCSE level wiring simple stuff and you have a fail safe for peace of mind for when not if the relay fails.
Half an hours job.

Ford Duratec engined trads including 3.7 Roadster from at least as early as 2004 to end of production used two relays to independantly provide high and low speed fan cooling assistance to radiator when needed. Each had a common +12 volt power feed and common +12 volts to coil. A Ford high power resistor plug was included in the circuit after the low speed fan relay wired to give lower voltage to cooling fan when its relay was triggered on coolant temperature by a ground from the ECU. If coolant temperature rose higher the matching high speed fan relay was triggered by an independant ground from the ECU and its output fed direct to cooling fan, effectively bypassing the resistor. I believe the low speed one remained triggered when coolant temp rose high enough to trigger high speed relay so you're never without some fan cooling assistance when needed if high speed relay failed to trigger. Each relay must be of type with diode protection to remove back emf spikes detrimental to ECU.