MCV36R Camry radiator fans not coming on, slowly getting hot

[nzgamer41]

Hello all,

I've got a 2006 MCV36R Camry Sportivo that's been a beauty to drive, but the other day I noticed the temperature crept up slowly past the halfway point to about 2/3 (I stopped the car before getting near the red).

I got it home and have done some basic diagnostics and found that I am pretty sure my radiator fans aren't coming on when they're supposed to. They come on when I turn the air con on, but don't come on when I start the car or when it's at temperature like I assume it's supposed to. Plenty of coolant in radiator and overflow so thankfully probably not cracked radiator/tank and the car doesn't quickly overheat, it took maybe half an hour idling in my driveway for it to nudge past halfway?

What would be the cause of this? Does this sound like a bad relay (the fuse marked RDI FAN is fine, I pulled it and checked for continuity with multimeter) or would this be a stuffed sensor somewhere? Mainly trying to work out if it's something I can do in my driveway with basic hand tools (like swapping a relay haha) or if I'd be better off taking it into the mechanics and having them swap out a sensor (I am a big fella and trying to reach stuff in the very full engine bay is a bit of a challenge on this car!)

 

Thanks for any advice,

-nzgamer41

[Tony Prodigy]

Hey bid fella, I think you're on the right track mate. If the fans aren't initiating when they should and the relay tested ok, then the water temp sensor may be the likely culprit and my bet too.

If you can get one from your local spare parts shop or even better, get one from Toyota for probably not much more, I'd go genuine and install it and see how it goes.

Let us know how you go.

[ESCO_AU]

Hi there mate,

it could also be the thermostat or the temp sensor.

I've attatched a few pages from the repair manual I have I hope they help 

Cheers Mike

[nzgamer41]

Hi, thank you both for the advice!

@ESCO_AU thanks for that! I will check a couple of things on there that I hadn't thought of.

I've done some more testing, the fans come on and off as usual and the car seems to hold temperature if my air conditioning is switched on. I plugged in a OBD2 scanner and chucked it on monitoring engine coolant temps and it stayed within reason but as soon as I turned the AC off and the fans weren't coming on it started creeping up to 100c. Unplugging the engine coolant sensor (which I did thinking stupidly it was the switch sensor, getting terms muddled up a bit) just made the car not start and then throw a check engine light for engine coolant temp sensor circuit which clearing sorted once i plugged it back in, so that one seems to be fine.

The radiator hoses also seem to actually open and have water flowing through so I am hoping it's not the thermostat.

I have pulled all 3 fan relays out and tested them all working, workmate of mine is an electronics engineer but was also pretty easy to hear when 12v applied that the relay clicked on. I have also tried just jumping the pins in the fuse box to turn the fan on and that worked.

I'm suspicious of the temperature detect switches, just to confirm is that the one that's at the bottom left (when facing the car head on) of the radiator? I've been trying to figure out where bits are from videos and things, but things seem to be slightly differently laid out on the previous gen camry that usually comes up when i look up "1mz-fe camry tempearture switch sensor" for example.

[nzgamer41]

Did some more checking after work, another thing I noticed is when the AC switches the fans on, they only switch on in like a slow mode? When I first got the car/when everything was normal the fans would come on quite fast when the car was warmed up. I'm pretty certain at this point it's the temperature detect switch, I just can't reach the one at the bottom of the radiator. I CAN get to the second one on the thermostat housing, haven't pulled it out yet (that sounds like a weekend job).

[Tony Prodigy]

20 hours ago, nzgamer41 said:

I've done some more testing, the fans come on and off as usual and the car seems to hold temperature if my air conditioning is switched on. I plugged in a OBD2 scanner and chucked it on monitoring engine coolant temps and it stayed within reason but as soon as I turned the AC off and the fans weren't coming on it started creeping up to 100c.

Luckily it is an AC optioned car because the Cooling fan will switch on and cycle for the AC to maintain the cabin temperature, and by virtue of this action it acts as a surrogate cooling aid for your engine's cooling system by drawing air through the radiator to help the heat exchanger or condenser reject heat for efficient operation of your AC.

Naturally, when you're AC is not in use, your problem is still there, which I still think it to be the water temp sensor. I'm not sure of it's location but if the info provided by Michael indicates this, then yes, I'd go after that before anything else. He also mentioned to check the thermostat, but I don't think that would yield much for what is happening here. The thermostat doesn't govern the fans as such, but only regulates the flow of water at a given temperature to help maintain a normal operating temp for the engine. Thermostats rarely go bad. Sensors do though.

We'll wait and see what you find. I'd be interested to see the outcome.