Hi everyone. I haven't posted in quite a while.
My 1995 850 T5R has a problem that I really need your help with.
Three days ago, I drove the car about 10 miles. no problem. Parked for three hours and when I got back decided to go get some gas.
At the gas station, steam was coming out of the engine bay on the right (passenger's side). The temperature gauge was in the middle.
I got out of line, parked, shut of the engine and opened the hood to find water coming out of the reservoir under the cap.
interesting. I'm thinking, low coolant, so I add some, start it up and drive about a mile and same thing happens.
Ok, I get it towed home.
i'm pretty good with cars, so I'm thinking, thermostat or water pump. so I order a new water pump and thermostat from FCP.
While I'm waiting for it to arrive, I remove temperature sensor by the thermostat, and test it in hot boiling water. I appears to be working, as temp rises, the resistance is lowering.
I then test the thermostat. in boiling water it opens at 90 degrees C (194 F). Hmmmm
I test the fan by grounding the fan relay and nothing. no fan. Also, no fan when I turned on the AC.

So, I replaced the water pump and thermostat. Took the fan apart and repaired it. Tested the fan relay and they now work.
I also went to a local pick a part and got another fan that works and tried that also.

Start the car and no fan and water boiling after a little while.

I then check the wiring of the temperature sensor all the way to the ECU. Continuity.
I then check the wiring of the two fan control wires all the way to the ECC. Continuity.

I make sure the connectors are tight.

Shoot! it's got to be the ECU right? I swap a used ECU and same problem. no fan.

When I ground the fan relay and the fan runs, It does not boil over.

I stared the car once and the fan came on instantly. I'm thinking, great!!! it works now, then It hit me. Why is the fan running with the car cold?

Shoot, I forgot to connect the temperature sensor connector. Car runs rough. Check engine light is on. NO signal from temp sensor.
Reconnect it, clear the code, start the car and no fan after warm, turn AC on, still no fan.

What the heck is wrong?

Maybe the temperature sensor?

I'm stumped.

Help!!!

thanks,

1995 Volvo 850 T5R 297,000 miles, (completely restored with engine rebuild, trans, suspension, etc.)
1983 Volvo 244T 321,000 miles (completely restored)
1970 Plymouth Barracuda, in-violet purple ground up restoration.

Hi _____,

You need Volvo schematics to work on electrical stuff.

Check fuse 31

+12V starts at the starter motor 6/25
there's an inline fusible link in the red wire
a branching point 23/7 (that I didn't see on the pictorial)
to pin 1A input of the engine fan relay 2/11
(2/11 is up top of the fan towards the passenger side)
Measure for +12V here first to see if the fusible link is gone!
this is constant +12V via the starter & fusible link hot or cold.

One or the other should work when the engine is hot.
two +12V outputs from engine fan relay :
Green at 1C to pin 2 of 6/29
Red at 2C to pin 1 of 629
The Engine fan motor 6/29
fan motor ground 31/55 on front of engine below pass. side intake manifold

EZK module (note the relay is triggered by the ECU grounding
the fan relay pins.)
(output 1) Yellow/white wire from pin 7 EZK to pin 1B fan relay
(output 2) Yellow wire from pin 22 EZK to pin 2B fan relay
31/33 is a critical ground for the EZK module

Find the Volvo 1995 850 wiring book: TP3907202 Nothing else comes close.
I had the schematic and location pictorial from the Volvo manual
but Brickboard gagged when I tried to upload the fan info.

If you remain stuck, email me and I'll send you the schematic.
See my profile for the email address.

Cheers, Bill