Fans

[Milex]

Hi guys , we’ll ive sorted prob with top hose collapsing , i tried.a new radiator cap and it didn’t really help , so then on inspecting a few of the other pipes I found the small one from rad to expansion tank was solid on the bottom elbow , cleaned it out sorted no more top hose collapsing😁,  .i have a question , at what temp should the fans come on, I’ve noticed that they come on when I turn ignition key to just off the start position on ignition switch or momentarily when I switch engine off ,but I never here them running even after a motorway trip and then sitting in traffic , any ideas 

[m4rkw]

If you're talking about the front fan that cools the air conditioning system, I think that should switch on almost immediately at an idle if the ac is running on most cars.

[Delphius1]

The main fan should come on around 90-100 degrees. I've not checked it on my cheap Bluetooth OBD2 dongle and phone, but most cars come on around that temp.

The secondary fan should be on all the time as soon as you switch the A/C on.

 

[Mylexrx]

thanks guys the fans both kick in at a point on ignition switch just before start up but then as I said theres nothing until I switch engine off and they kick in briefly again

[m4rkw]

If they move at all that means the fans themselves are probably working. Are you testing them only at idle? Is the air conditioning on and working? Have you run the car up to temperature?

[Mylexrx]

Hey mark yeah I’ve had it up to temp , just above half way on gauge it never goes higher, air con works but I havnt had it on when testing, I’ve also had car on motorway and then let it idle and still nothing 

[Mylexrx]

all up to temp ,never goes over half way,even been up motorway then let it tick over still nothing

[m4rkw]

Motorway speeds aren't generally going to produce a lot of excess heat because you've got 70mph wind hitting the front of the car and going into the engine.

Sitting at an idle, especially with the ac compressor running, will start to generate heat. The fact that the fans move and then cut out seems to indicate the fans themselves are ok but the mechanism for activating them may be faulty. Maybe a bad thermostat or relay or something along those lines. The temp needle should be bang in the middle, if it's reading over that might indicate it's getting too hot which would make sense if the fans aren't coming on.

Do you have a code reader?

[Mylexrx]

No mark I don’t at moment , I’ll run it up to temp on idle with air con on and see if they come on , I’ll let ya no

[m4rkw]

Keep an eye on the gauge if you're doing that, if the fans aren't coming on when they should then idling with the compressor on could cause it to overheat.

[Mylexrx]

Will do thanks