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Radiator fan not working and possibly A/c plz help


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when running the car up to temp I'm finding the radiator fan does not cut in and out even when the cars been sat running for a long time.

Also when I turn on A/C am I correct in thinking the radiator fan should kick in instantly and stay on while the a/c is on ?  Because its not running then either.

The fan turns freely,  I have changed  the white box  relay/ resistor shown in photo below to no avail, 

I * think* I have been over all fuses related to the rad fan and  a/c  but if Someone can tell me which number fuses and relays  I should check  in case I have missed any that'd be helpful.

Failing that other than using a voltage tester on the loom connecting to the fan to see if there's a current  and find out if the fan is bad I'm not sure what else it can be.

The coolant temp sensor appears to be working,  as the "cold" symbol light goes out after a few minutes.

Its a 1.0 1krfe engine 06' mk2

Any help appreciated

Thanks - Teresa


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I would suspect that the fan will not start if the a/c isn't working. Does the fan switch on when the engine cooling has reached a high enough temperture? e.g. up to operating temperature when the car is not moving like stuck in traffic. Next time you arrive somewhere, assuming it's been sufficient to warm up the engine, open the bonnet and leave the engine idling to check if the fan works then. If there's a high temperature warning light like the low temp. light keep an eye open for that to prevent overheating.

When was the last time the a/c gas charge was checked? If it is too low the a/c will not run and as a consequence the fan.

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Teresa Hi, there's no reason for the fan to run when you switch ON A/c, until the load temp rises. What sort of temp are you expecting the fan to kick in at?? Don't go by the gauge, it's calibration could be anywhere (it's only a guide) Try lying a Thermometer on top of the Radiator to get a better idea of Temp.According to my Maintainance book, Fan 'ON' at 93* C and 'OFF' at 86* C Along with the 2 x Fuses, there is also a Relay to check out.

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Thanks guys , A bit more information...

The coolant cold light illuminates on startup. Goes out after a few mins. So whatever reads the temp for that appears to be working, fan temp switch I assume?

I've ran the car for a long time until its without doubt above temp for the fan to kick in but it just never does - you can leave it forever and the fan wont come on , and the overheat light never illuminates even though the fans not kicking in  and it is overheating.

Bomber 209 problem is There is no gauge on the 1ltr  as its digi dash just a " blue temp cold "  light that goes out once car is warm and a red one to indicate overheating which I've never seen / doesn't work, yet the car is getting too hot .

I've just got the car  so not sure on the ac. doesn't appear to blow very cold, there's no noticeable or audible sound or engine load / rev increase  when the ac button is pressed.  Radiator fan doesn't start or come on and off over a time period either..

I can live with no a/c but I just wanted to know when the radiator fan should run when the ac is on so I can diagnose that the cooling fault is not Being caused by a bad fan motor, ( if it kicks in when ac is on I know the fan would work when the engine needed cooling -  pointing to a fuse / relay or fan temp switch. ( trying to whittle down possible causes starting with the cheapest issues)

 Do you have the fuse numbers and locations I need to check and the relays  be much appreciated  ( car had no owners manual and don't have a Haynes manual yet )  or perhaps a online diagram or PDF ? 

Thanks again for replying  - teresa

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Okay, although the fan doesn't run doesn't necessarily mean it is faulty, there are various reasons for this such as the engine taking a very long time to reach the temperature required for the radiator fan to activate (winter is not the best time for this test) it could be taking a lot longer for the engine to reach that temperature due to the thermostat being jammed open, you mentioned running the ac system, the fan should cut in and out during its operation if the ac is working as it should, to test it at this time of year firstly make sure the engine is warm and the ventilation system is blowing out warm/hot air from the ducts,( set the cabin temperature dial all the way to HOT (red) and NOT cold (blue)), turn the fan setting to high and with the bonnet up check that the ac pipe (located at the front of the engine , left hand side of the radiator, it's a bare aluminium pipe that disappears down into the engine bay) is icy COLD, if true then the radiator fan should kick in and out.

If the ac pipe does not get icy cold then the above test is not valid and the ac system will require servicing.

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with the a/c off the fan wont turn on until the engine gets hotter than operating temp if stuck in traffic etc otherwise it doesnt come on

with a/c on the fan should start immediately and then cycle on and off 3 or 4 times per min

but even with the a/c fan cycling if it gets too hot it will come on permanently and sometimes at a higher speed (but usually in the summertime in very heavy traffic)

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Thanks all after further investigation the fan does cut in at high temperature it just takes an awful lot longer than my starlet , had to hold car at 2,500 rpm for a while  after idling for a long while to get it to cut in .  the a/c needs a regas , it doesn't blow icy cold  thanks again everyone .

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Don't expect your fans to work as you want them to when you get your AC serviced. Toyota's engines are crazy efficient, much better designed than most of the other engines and so take a long time to warm up and don't waste a whole lot of energy into heat.

What weather is it where you're testing this? If it's anywhere with a winter then it's not much higher than 10°C probably, it's impossible to get my fans working in such conditions even in traffic with AC on and whatever else, in lower temperatures diesels are even cooling down, enough said.

If you aren't connecting computer to your car to see what temperature it reports then it's anecdotal and it probably doesn't overheat.

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  • 9 months later...

Hi guys

I also have a radiator fan that is not kicking when the engine is hot,let alone the AC as I just re-gased it recently. Also,the resistor that Tessa posted a picture of here,I disconnected it because it was getting really hot on the car and getting a bit of smoke. Any help will do

Thanks in advance

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