Hi all,

My wife was driving my 2001 S60 2.4T home from work and got stuck in rush hour stop and go traffic on the highway. She had the the A/C running and the car started to overheat. (the message center told her to pull over and stop the engine.) She turned off the next avail exit and by the time she pulled over the temp was at full tilt hot.

I arrived approx 30 min later and the temp gauge was at half when I turned the key. I also checked the coolant reservoir and it was full. No signs of a coolant leak at all.

To be safe I left the car and returned a few hours later when traffic died down and was able to drive it home approx 25 min away on the highway. I had a scanner connected as I drove to monitor the engine temp and the temp would reach 199F then start to fall. Once I got onto the highway it stayed at a constant 192F and I got it as low as 188F with the heat running. With the AC running it stayed between 192 and 195F. Once I got home and idled it with the AC running it climbed to 220F before the fan kicked in and it came back down.

Not sure if it really did overheat and if it did then why? The wife will be taking the car again later this week and I'm afraid it will overheat again in rush hour traffic.

Any ideas?

 

When the A/C is on does the cooling fan run all the time?

 

Sounds like a cooling fan problem. Not the fan itself, but the sensor that kicks it on. No problems with temps on the open highway, no apparent thermostat problems, no low coolant or leaks, and apparently the water pump is working. Idling creates the trouble, and the fan doesn't kick on until its really hot. Not sure what gizmo governs this function, but that's my first stab at diagnosis of the problem. You've eliminated nearly everything else.

 

tech, I'll check if the cooling fan comes on with the AC and report back. Should it run continuous with the AC?

Does the ECT sensor control the fan? if the fan is not coming on or coming on late would that be the ECT?

 

Yes it should run at all times with the A/C on.

No the ECT does not I believe the high pressure switch controls it.

 

Ok, check it last night, doesn't look like the fan is staying on continuous with the AC. To be honest I don't know if it ever did, but I could be wrong.

Turned on the AC and the fan didn't come on immediately. About 10 seconds later it came on and ran for 30-45 seconds then turned off.

You think it could be the high pressure switch? Where is the switch located?

thanks again for everyone's help.

 

It could be the high pressure switch it is a pain to get to as well. It is on the dryer. But the system has to be evacuated to install it. And sometimes it is easier to remove the front bumper to get to it.

 

Thanks Tech. I may take need to take it in in that case. Hasn't overheated since so I may just wait and see if it re-occurs.

Cheers.

 

Keep me updated on what happens.

 

How long have you owned the car and does it get serviced by a dealer? There was a recall on those fans a while ago. Also throw in a t-stat and ect sensor. Its cheap insurance. My guess would be a temp sensor or a cooling fan.

 

Have had the car since 2004. So far it's always been serviced by the dealer but I'm looking for a reliable mechanic now. I do service what I can myself...brakes, oil changes etc. -easy stuff.

The cooling fan was replaced under warranty shortly after I bought the cars so should be good there. Last Feb/March I changed the thermostat b/c the car was not heating up enough in the winter. It's been good so far....except for this one overheating incident.

I was thinking of replacing the ECT sensor myself..looks very easy - but from the feedback so far I don't know if that would help. Couldn't hurt. If it happens again I may try that but I hate to throw parts at it hoping to find the solution.

Will let everyone know. thanks.

 

Hi all,

New update. Did the same thing today in rush hour stop & go on the highway -wife said the temp gauge started to climb past halfway then within seconds it went all the way to HOT. It was pretty humid out today too and she wasn't moving much at all.- traffic crawls.

Same thing - I arrived 30-45 min later, the temp was half. I drove it home myself on the city streets and it was fine.

Here's where I either found the problem or screwed something up. I disconnected the electrical connector to the ECT and started the car. Temp gauge didn't move. I reconnected the sensor with the car off and restarted it, thinking the guage would start to work again, but no. Now it's reading nothing even though the car is hot.

The fact that she said the gauge climbed to hot within seconds and now it's dead, would you suspect the gauge was giving a false temp reading?

Thanks all.
Cheers.

 

I would suspect the ECT.