a few days ago, (the day after I had my A/C system evacuated and recharged) I noticed that my radiator fan came ON directly after starting the car and stayed on a few minutes after shutdown. It was a cool day, obviously not overheated. so, I have been snooping around, and found a thread in the XC90 section of the sight with some 2004 XC90's having this issue:

https://volvoforums.com/forum/volvo-...tart-up-61301/

They talk about replacing coolant temp sensors, but that doesnt fix the issue. they ended up replacing "boost pressure sensor". However, I drive a '99 AWD S70 and as far as I can tell, there is not boost pressure sensor?

Has anyone else had this issue? any input is appreciated.

 

I believe by "boost pressure sensor" they are referring to this part:

Volvo Air Temperature Sensor - Genuine Volvo 9445153 | FCP Euro

maybe?

 

Any codes?

Coolant temp sensor is likely your problem.

 

Hey rspi, thanks for your reply! I love your maintenance/repair videos! I've watched alot of them.
Just pulled the codes:
P0118 - Engine Coolant Temperature Circuit High
P0135 - 02 Sensor Heater Circuit

Based on the P0118 code, I do believe that my coolent temperature sensor (ECT) is bad. just ordered a new one.

Originally, I didn't believe this was the issue because the temperature gauge in my dash was still seemingly functioning properly.

 

You would think that the gauge gets it's reading from the sensor, I don't think it does.

 

I think you are overlooking the A/C evac/recharge clue. When the A/C is running, the radiator fan runs, 100% of the time. You had the A/C service and now its doing that. Is the compressor running 100% of the time? Does the A/C compressor run at all? You may find that the A/C "system" is telling the car, in some way" that the A/C is on.

 

if that doesn't work replace the thermostat (you will have to pull off the upper housing to swap out the temp sensor anyway) I just had the same problem and replaced my temp sensor but it wasn't until I replaced the thermostat that the problem was resolved.
I talked to a very experienced volvo mechanic about the issue and he said that it's virtually impossible to tell whether the temp sensor or the thermostat is the one causing the problems because of the way the system is set up so they just replace them both at the same time.

 

hey guys, as an update: I did replace the ECT (coolant temperature sensor) and seems that the problem is remedied.

Shadowfist,
I did not replace my thermostat because I had done that a few months ago. I was thinking that the thermostat could have contributed. I will keep this in mind for the future. Thanks!

kwatt,
are you sure that the radiator fan runs whenever the A/C is on? I will have to experiment more with this. Will test this afternoon. I was sure that it had something to do with the A/C service. The timing was too coincidental.

 

Every vehicle I have ever owned with an electric fan turns the fan on when the A/C is on. Try it out.

 

hey kwatt, you are completely correct. I hadn't noticed before because the radiator fan doesn't start up until 45 - 60 seconds after I turned on the A/C. and the fan turned off as soon as I turned the engine off; which I believe to be proper function.

I will keep this in mind for future issues. Everything seems to be functioning properly now. Thanks for the help!