Intermittent overheating problems

AaronA · Post by **AaronA** » 08 Jul 2012, 06:17

I have a 2001 V70 T3 and it has been having some trouble with overheating. It began with A/C problems - my wife complained that the A/C would occasionally shut itself off. Last week, on a 95 degree day, with three kids and an ice cream cake in the car, the A/C stopped working completely. I was stuck in traffic when it happened and suddenly noticed that the temperature gauge was reading all the way hot. The little warning triangle went on and the car told me to pull over as soon as it was safe. I tried to fight my way over to the side of the road. By the time I got there, the car was telling me to shut it off and the coolant was boiling. I'm hoping that the 20 seconds of overheating did not fry my head gasket. I sat on the side of the road as the kids and the ice cream cake started to melt. My wife came and picked up the kids and the cake and I sat with the car. After it cooled off and I refilled the coolant reservoir, I drove it home with no A/C and the temperature gauge never left the middle position.

I tried to duplicate the overheating in the driveway, but couldn't. The cooling fan came on normally, the A/C was blowing at 45 degrees (85 degree day), and the temperature was normal.

I drove it on short trips in the next few days and the temperature was fine. On Friday, I drove about 45 minutes to pick something up from a friend. While on the highway with A/C, the temperature was normal. In traffic afterwards, with A/C it was normal. Then I stopped at the bank, parked the car for 10 minutes, returned and sat in light traffic with the A/C. The temperature gauge was fine, then suddenly it started to creep upwards. I shut off the A/C, turned on the heat and it came back down. When I got to my friend's house, the fan was blowing normally and the temperature had stabilized. When I drove home, I had to put on the heat twice in traffic, then it was fine on the highway with the A/C.

Has anyone ever had anything like this happen? My guess is that the cooling fan relay is intermittently failing and so I was going to change it, but where is it? It's not on top of the radiator shroud like on the 850's, and there is no relay in the engine compartment fuse box for a cooling fan.

I'm assuming that since the temperature gauge is working, it is not the temperature sensor. Or could it be the whole fan that it intermittently failing? I'm hoping the try cheaper solutions first.

Thanks!
Aaron

Post by **DGM** » 08 Jul 2012, 22:23

On these models there is no relay. If you look at the fan assembly you will see a control module on the side. This module has 3 wires going to it. The big red and black wires are the power leads. The magenta wire is the lead to the ECM. Conditions on this lead can't be tested easily since it is PWM (Pulse width modulation). The speed of the fan is controlled by this wire.

Volvo replaced many of these fan assemblies (2001 models) in 2005 on a recall. You can verify with your dealer if yours was part of the recall. With the Vida-Dice system Volvo technicians can analyze fan operation history and tell if it is intermittent.

Personnally I had this problem 1 month ago. I was lucky and managed to control temperature as you had done. I kept the temperature down without boiling over.

The module was defective. It is hardwired to the motor. I changed the fan assembly with one from an XC70 2001 that was replaced in 2005 by the recall. I had to splice my electrical connector on the new fan. They were different.

If you are stuck in a traffic jam without an operating fan the temperature will run off quite fast as you experienced.

Have your codes analyzed with Vida-Dice before to spent $ on a new assembly. This will confirmed if it is intermittent.

AaronA · Post by **AaronA** » 09 Jul 2012, 06:15

Thanks! I'll bring it to the dealer and have them diagnose it. I had been hoping to avoid that, but I guess it will be money well spent.

Post by **DGM** » 09 Jul 2012, 08:58

This is the recall I was talking about.

http://www-odi.nhtsa.dot.gov/cars/probl ... mmary=true

AaronA · Post by **AaronA** » 09 Jul 2012, 09:37

I just made an appointment with the dealer. That recall was, unfortunately, already done on my car. I'll let you know what they come up with.

Thanks!

AaronA · Post by **AaronA** » 26 Jul 2012, 06:12

It was the cooling fan. Vadis did not have a history of what happened when the car over-heated, but it did show that the cooling fan signal was absent. I got one from FCP and installed it. The car is running normally now.