Radiator fan stays off

zarossi46 · Post by **zarossi46** » 09 May 2022, 09:04

I need some help with my wife's Volvo. I recently serviced the vehicle by replacing the timing belt, vvt gear, replaced engine and transmission oil. The car has done about 180 000km. After the service everything seems to be ok, except the radiator fan does not come on and the A/C compressor clutch does not pull in. I am not sure if the two are related. I have checked the wiring, relays and fuses and can't find anything faulty or unplugged. The engine have idled for a long time until temperature gauge was 3/4. Still the fan stayed off. The fan normally starts when the temperature gauge is just above 1/2. There is no engine fault codes.
I need some help to troubleshoot this problem. Any suggestions please.

Volvoblackdog · Post by **Volvoblackdog** » 18 Aug 2022, 21:59

Hello, Ill start by stating I am the Green one! I am trying to locate a similar problem. Did you try to see if the fans work with direct connection and if not try that to see if the fans are working or not. Otherwise if you tried the relays and fuses then there could also be a faulty water sensor. However, you stated that your temp gauge is indicating. If all else fails try looking into a short in your wiring to the fans. Try a continuity check for each fan.

Good Luck

Navservice · Post by **Navservice** » 22 Sep 2022, 14:10

I had similar problems a while back and am only now getting to the root of all varied cooling system problems. They've all been pretty simple up to now.

#1 - NEVER trust the temperature gauge on the dash. Mine rises to midpoint as the thermostat should be opening and stays there even at 250 degrees. The temperature gauge uses one temp sensor and the OBDII uses another. Get a cheap OBDII bluetooth adapter and use it with the Torque app. I've now gone as far as buying ($160) a dashtop display (ScanGaugeII, same price on Amazon as it is at Autozone) that plugs into OBDII and displays all kinds of things. Some unimportant, others like water temperature, vital. Also gives me a boost gauge since that data is available from OBDII.
#2 - I imagine you already know there are two radiator fans. One comes on whenever the A/C is on, the other comes on at 230 degrees in my case (verified by OBDII reading). In both cases these fans are controlled by those most unreliable of automotive devices, relays. These cars are getting a little long in the tooth and those relays are not reliable. Check your documentation because I can't remember off the top of my head which relay controls the basic radiator fan. Swap out that relay with a similar one that doesn't get much use - the immobilizer relay. This could also confirm the status of the fuse and fan motor.
#3 - Engine gets very hot sometimes, other times no problem. It could get hot waiting at a stoplight then cool down once moving. This led me down the path of a fan problem, which it wasn't really. It didn't help me any that there really was a bad relay for the radiator fan. My tactic was to run the air conditioner (fan) to keep the water temp within reason. I could drive from Orange County, Ca to Kingman, AZ 325 miles through the desert without a problem but waiting in line at In'N'Out presented a real danger to my engine's well being, this after fixing the fan problem. Remember what I said about these cars being long in the tooth? Mine's 22 years old. I only recently found out (how is the subject of another post) that my coolant reservoir tank, the plastic bottle, has a hairline crack. Remember that this is not just a surge tank, it is an integral part of a pressurized cooling system. The crack would leak only when the cooling system pressure was up to about 20psi, when the temperatures are high. At anything below about 215 degrees there would be no leak. I was in Kingman when I found this out and I needed to get to CA very soon, no time to order a new tank. I plastic welded my old one finding many other cracks almost as bad and arrived last night. First order of business is a new tank. Many recommend the original Volvo part.

Navservice · Post by **Navservice** » 16 Oct 2022, 21:22

Oops, in my previous post I said there were two temp sensors. That is incorrect, there is only one, it is used by the OBDII and the temp gauge. I stand by my statement that if anything is suspect the temp gauge is less believable.