I would like to know from your driving experience if you can provide the following detail:

What is the minimum outside temperature when the radiator fan kicks in while idling at a redlight ?

Conditions:

- driving in the city, moderate traffic

- 2 passengers, no luggage

- normal driving style

Outside temperature has no bearing on the matter. The fan is governed by the temperature of the water in the radiator. If you're on a lot of stop/go traffic then the engine warms up a lot more. My Fun Truck fan would kick in after about 2-3 minutes of stop/go after 40 minutes on the motorway.

As inspector lesard at police acadamy said "there are many many ways" of looking at this. how long is the redlight for example. Typically i find my 1.6glxi fan comes on after 4 to 5 mins at idle at 10c....why do you ask?

so you mean the radiator fan kicks in at idle after, let's say 5 minutes, no matter if it's winter freezing or summer scorching ?

Typically i find my 1.6glxi fan comes on after 4 to 5 mins at idle at 10c....why do you ask?

I want to know when should I start worrying for overheating based on that circumstance.

so you mean the radiator fan kicks in at idle after, let's say 5 minutes, no matter if it's winter freezing or summer scorching ?

Yeah. Cooling is dependant on air flowing through the radiator. The temperature of the air is a secondary factor......if the air isn't flowing, it doesn't matter how cold it is.

If you're worried about over-heating, disconnect the houses, give the entire system a good flush with clean water, re-assemble and put a good quality anti-freeze in there. Should help to start with. The fan is designed to kick-in, to give air-flow, to prevent over-heating. I'd be worried if the fan was on and the temperature gauge was still going up.

cool I really appreciate your advice.

But I still find hard to overlook the influence of environment factors. there's a 40^oC temperature difference between mid summer and mid winter, which is not negligible in how soon and how often the fan should kick in.

last winter we had some -10^oC (14^oF) outside. I started the engine while cleaning the snow and ice off the car, and after 10 minutes of idle the fan kicked in. that seemed odd to me, since I remember having the fan kick in only in summer...

anyway, just to be relieved of the overheating issue this spring of 2012, can you or somebody else count the time the fan kicks in FIRST time and then SECOND time ? test should be made starting the engine cold and letting it idle with bonnet closed.

There appear to be two main types of rad fan switch/sensor....the difference being the coolant temp they activate at.

[Even in the depths of winter, if one is idling a couple of feet behind a nice hot exhaust pipe of the car in front, the temp will rise quickly...and the fan will cut in]

I fitted some time ago, a low temp rad fan switch, from Jorily.

I did this because the previous switch had the fan cut in when the temp gauge was around the 100 mark..[not an absolute of accuracy, I admit]..

From experience I am conscious of the weakness of the 136 motor when overheated....so I wanted the fan to cut in earlier, hence the fitting of the low temp switch.

Now it cuts in when the temp gauge is just over half way, when idling [not when moving]...

The switches work like central heating thermostats....so should cut in when idling for definite.....whatever the climate..

How cold the outside air temp is, will only affect how quickly the fan brings the coolant temp back down to the required temp, for the fan to cut out....not whether it cuts in at all.

Observe the temp gauge...and act on it if it rises unduly high.

However, word of advice folks......if over the winter, the fan rarely if ever cuts in [depends on driving habits]...come the warmer weather [when fan is more likely to want to operate]...check to see if [a] the fan actually works, by shorting out the switch, and check to see if the rad fan switch is actually still awake!

Once or twice now, I've noticed when visiting city traffic, how hte temp rises more, but the fan didn't cut in as expected......bonnet up, and giving the switch a smart tap activated the fan........and keeping a watchful ear open over the next few days saw the fan switch working as it should......but then it needed another tap today...

The switch has gone lazy....but I don't want to hard-wire a bypass switch to the dash, so...maybe the switch just needs some work to do......then again, maybe I'll just replace it?

Lordy, I'm back to typical Skoda paranoia now!

Just take the thermo switch out of the radiator, and test it with a multimeter and a thermometer while it's in a pan of water that you heat up. Find the temp it's supposed to work at, and it'll either be OK or not. I think you're massively over-complicating the issue!

Just take the thermo switch out of the radiator, and test it with a multimeter and a thermometer while it's in a pan of water that you heat up. Find the temp it's supposed to work at, and it'll either be OK or not. I think you're massively over-complicating the issue!

Lets face it its even simpler than this.

Leave the car idling and watch the temp gauge and if the fan cuts in at some point and then it runs for another 15 mins or so without overheating its fine.

Obviously you need a working temp gauge, but they're usually pretty reliable compared to the switch.

To be frank if you're taking the switch out you may as well replace it.

I don't think Felicia temp gauges are well known for their reliability... And for £10 I'm not sure I'd replace a thermo switch just because I'd removed it! I've suffered a boil over on a queue for a stage start because of the gauge being inaccurate and the fan switch not working.