124 Radiator fan relay (Diavia)

[philiggy]

Anyone know were I'll get an electric fan relay for a Diavia Aircon system, I assume it must be faulty as I've traced the wiring all round the car and can only find one fuse, next to the relay on the N/S inner wing, which is fine


Phil

 

[grober]

The Air handler fan motors are known to fail on these? there will also be several fuses/relay/s inside the main fuse box beside the brake servo unit.

 

[nick mercedes]

Anyone know were I'll get an electric fan relay for a Diavia Aircon system, I assume it must be faulty as I've traced the wiring all round the car and can only find one fuse, next to the relay on the N/S inner wing, which is fine


Phil

http://www.readerair.co.uk/parts.html

 

[philiggy]

The Air handler fan motors are known to fail on these? there will also be several fuses/relay/s inside the main fuse box beside the brake servo unit.

I've looked, other than 1 relay and fuse on the inner wing theres nothing else, not in the fuse/relay box, under the dash or any where.

I've just put 12v across each of the fans and they both work fine.

phil

 

[Number_Cruncher]

How are you cheating the system to make the fans come on during your tests? are you testing low speed, or high speed function?

I *think* there are 2 possible ways, by mimicking high engine temperature, or, by mimicking high refrigerant pressure.

Edit: forgot to say, if you want to compare voltages / currents around the system, I can take some measurements on mine - I don't have a wiring diagram.

 

[philiggy]

How are you cheating the system to make the fans come on during your tests? are you testing low speed, or high speed function?

I *think* there are 2 possible ways, by mimicking high engine temperature, or, by mimicking high refrigerant pressure.

Edit: forgot to say, if you want to compare voltages / currents around the system, I can take some measurements on mine - I don't have a wiring diagram.

Hi Number Cruncher,
My electrical know how is very basic, I knew the fans didn't come on with the aircon, so to see if the fans worked I took a lead from the battery to the fan motors they worked so I knew they weren't siezed or burnt out.

The only fuse I can find is okay there is power to dash switches, pump, and sensor, so I'm going to try a new relay in to see if it works.

thats as far as my understanding goes

Phil

 

[Number_Cruncher]

Hi Phil,

I don't think my fans come on straight away, even if the aircon is on, but, after a short while the fans do come on. The fans on mine come on far too soon for it o be engine temperature, so, I'm fairly sure it must be by monitoring the air conditioning refrigerant pressure.

It's entirely possible that your fan control system is OK, but that there's a fault elsewhere.

I wouldn't rush to throw parts at it without checking. The relay itself should be easy to check - typically you would connect a battery across the winding, and check the relay closes.

See

http://faculty.ccp.edu/faculty/dreed/AT121/at121files/relays.htm

for more.

 

[Dieselman]

Invest in a cheap (£5) multimeter and use the voltage test.

The main pole of the relay should be fed with 12v and the coil with Gnd and an active 12V when required.
This causes the relay to close so 12V is fed to the fans.

 

[philiggy]

Hi Phil,

I don't think my fans come on straight away, even if the aircon is on, but, after a short while the fans do come on. The fans on mine come on far too soon for it o be engine temperature, so, I'm fairly sure it must be by monitoring the air conditioning refrigerant pressure.

It's entirely possible that your fan control system is OK, but that there's a fault elsewhere.

I wouldn't rush to throw parts at it without checking. The relay itself should be easy to check - typically you would connect a battery across the winding, and check the relay closes.

See

http://faculty.ccp.edu/faculty/dreed/AT121/at121files/relays.htm

for more.

Thanks for that, I'll give it a go

Phil

 

[philiggy]

Invest in a cheap (£5) multimeter and use the voltage test.

The main pole of the relay should be fed with 12v and the coil with Gnd and an active 12V when required.
This causes the relay to close so 12V is fed to the fans.

I've got one I'll dig it out and try

Phil

 

[grober]

Sorry if I confused people I was talking the air circulation fan inside the car, not the cooling fans in front of the radiator.