Engine: B5234: VIDA cannot activate Cooling Fan, but A/C does

[Tony10ajf]

My first question on this really useful forum after much searching on existing posts. This might be a challenge for somebody with the knowledge !

My car's a 2002 V70 T5 with 155,000 miles which I've had since 2004.

The cooling fan only comes on at the instruction of the A/C, which it does on the lowest speed.

The engine smells and feels hotter after a run than it used too, but has been this way for at least a year probably more.

I have not suffered an obvious overheating, however the coolant temp definitely runs a needle width hotter than dead center that it did previously though I understand these things are not precise.

I cannot remember the last time the cooling fan ran on after the engine was switched off, but it definitely used to do this many years ago.

The coolant does not bubble at all.

VIDA says that when at idle after the engine was warmed up enough to have the temperature gauge in the middle, that it's at 87 deg C which seems ok. When I rev the engine for a few mins at 3000rpm without A/C on the engine temp creeps up to 93 deg C and looked like it would continue upwards. As soon as the A/C was turned on (triggering the cooling fan) the temp dropped back to 87/88 deg C.

I did a coolant change very recently with 50/50 Volvo coolant after flushing out all the old stuff with de-ionised water, but this made no difference. I am pretty sure there are no coolant leaks as the reservoir stays full and green.

With VIDA connected, it correctly shows that the A/C has triggered the coolant fan onto it's lowest of 3 settings.

However I cannot get VIDA to Activate the fan on any of the three speeds. I see there are two screens to do this on, but neither was successful which suggests to me there is a signal issue somewhere.

Any thoughts on where I should look ?

thanks

Tony

[cheshired5]

The fan controller is not unknown to go bad so you could begin with a multimeter and measure lives and ground at the controller whilst trying the Vida activations.
In the end a swap of the whole fan assembly with one from a breaker may turn out to be the cheapest and easiest solution.

[VOLVOBOY]

Hi.
The A/C and engine cooling are two different systems. From your description it sounds as if the A/C is working normally.
If there were a problem with the fan i don`t think it would work on either system. There may be an issue with the control ie. with fuses or relays but i think the fan itself is OK.
You described a hot smell . That suggests an overheat problem so i would concentrate more on the engine cooling side of things.
After the long run , and with the engine idling does the temperature gauge rise from the mid-point without engaging the A/C ? Does the cooling fan engage at all ?
If i remember correctly , there is an engine temperature sensor in addition to the thermostat. One of these may be the problem.
Has this problem only started since changing the coolant ?
Go this route first as it`s the least expensive and if no joy then do as "Chesh" says and look at the fan controller.

[VOLVOBOY]

Hi , me again..
I remember now..
There is a coolant level sensor in the expansion bottle. (this is where i was confusing myself).
The engine temp sensor ( by the thermostat ) is a 2-wire sytem in that one wire goes to the temp gauge and the other wire goes to engine management.
So, you could have one side working fine and the other side be duff.

[Tony10ajf]

I've never seen the temp gauge rise more than a fraction above the mid point after a long run, but then I always have the A/C on which is the only thing triggering the fan ! It only triggers it onto the slowest speed but that seems enough to bring the temps down to below 90 C according to VIDA.

The cooling fan never seems to engage apart from when the A/C is on. As per first post I can't get VIDA to trigger the fan either.

I'll look at the sensor and wiring before trying a fan module swap which looks quite a tight task in terms of space. Will report back when I get some progress.

thanks all for assistance

[Tony10ajf]

Just as a very late update, hopefully to help anybody with similar symptoms:-

I changed the temp sensor and thermostat, which for a V70 T5 petrol means the whole housing, that requires the power steering pump to be moved to get access to the screws holding the housing. The thermostat had quite a lot of sediment in it and did not move smoothly so I'm pretty sure it was not fully opening and/or closing so affecting the engine cooling. For info it was a 90 deg thermostat inside. This definitely eased the burning smell in the engine bay after a run.

The Vida (VCX Nano) still cannot activate the fan but this must be a fault of the Vida/Nano, so a different issue. Recently when getting the engine warm to check the transmission fluid level at 80 deg C, the fan did come on at low speed without the air con, but only at a coolant temp of 100 deg C which was achieved on the drive on a hot day with 2000rpm for a while. So at least I know the car is able to activate the fan without the air con operating.

[nickbw898]

I would simply get a complete fan shroud and controller from a breaker (mine was £50 inc delivery) and change the old one out, it's very easy and will be a complete fix. The Bosch controller is impossible to fix and it can fail in such a way the fan runs until the car battery is flat. Also with these interference engine a overheat can be very expensive.