Hey all, the fan on the wagon is not cutting on. The odd thing is there have been no OH issues, but I noticed this morning that the fan did not come at all when it was idling for 10 minutes. Is this common and where do I start? thanks. The coolant temp stays right in the middle or just a hair above FYI if that helps.

 

Well, I just finally found a thread for the "auxillary" fan and it says that it doesn't come on unless the A/C is on, which does not currently work in my car. Hmmmm, gotta do more digging.

 

Well, that's wrong - unlike most other cars that you've owned, the fan does not come on automatically when the A/C is switched on; it only comes on to prevent overheating. I agree that if it did work like most cars it would certainly cool better, especially in traffic, but in order for this to happen you have to do some rewiring. A/C is not what Volvo did best when these cars were built. If you doubt this, try finding the high side port for the A/C...

 

Well, I do don't doubt that the A/C isn't the best, but that wasn't my question. my question is how to get the relay fan working as it is not right now. It never comes on. Again, the car doesn't run hot, but it does run hotter than I would like and I am not sure where to start looking.

Still waiting for an answer since I know nothing about these cars and have no idea where to look.

 

different years have different setups, too. my 92 740T has a 2-speed electric fan and no mechanical fan. the electric fan is on low all the time, and goes on high when the engine gets hot. it also has a larger radiator than earlier 740/940's

I don't have a 89 wiring diagram, but on the 1991 7/9, the fan was one speed, and the relay comes on when EITHER the thermoswitch on the radiator is 'hot', OR the AC pressure is high (pressurestat on the high side of the AC). If you want the fan on all the time with the ignition, unplug the thermal switch, and short the two pins together (blue-black to black, which is ground)... this will activate the relay any time the ignition is on. this thermal switch is on the right side of the radiator, near the top.

 

Slider, why do you suspect the car is running hot, or "hotter than you'd like"? How did you measure the temperature? Is the gauge showing hot? These cars already have a fan, the direct mechanical one which is adequate for most conditions. The electric (A/C) fan is for when the engine is loaded by the extra duty of the A/C. In your case, the A/C being inop, you shouldn't need that fan...

 

note, too, your temperature gauge has a built in hysteresis, such that if the temp is anywhere in the 'normal' operating range, the needle sits dead center. it only goes above the center if the engine is 'hot', and pegs if its 'too hot'.

 

thanks pierce for the clarification. This definitely helps.

I am not sure if it is running hot because I don't know what "normal" is for these cars. The needle sits dead center and just barely above that if sitting in traffic. It doesn't act hot, but I wasn't sure. It sounds like it should be ok though based on information here. Thanks for the input!

Well, it seems like it's ok then. It never really moves except when sitting in traffic and then it only moves a tiny tiny bit. I'll check the relay stuff and maybe see if it at least comes on if I cross it.

 

ASSUMING your temp gauge and sender are all in order, then the time to be worried is when that needle heads for the top of the scale. by then, your car will be quite hot, you'll likely smell burning stuff if you look under the hood (or at least, the smell of way-too-hot-metal), and if you were to continue running it the power would drop way off and you'd hear/feel extreme 'knocking' or 'pinging'. when the needle hits the top of the scale, its time to shut it down ASAP, don't even try to go another mile.

 

Not sure I understand the problem - The fan only comes on when the car is starting to get hot, you say the car doesn't run hot, but you're unhappy because the fan isn't coming on??

 

'hotter than you like' ?? engines are SUPPOSED to be fairly hot, coolant temp of a properly working engine is right around boiling at sea level pressure (its pressurized so it doesn't boil). if you use an IR thermometer, the side of the engine block can be up in the 220 degree Fahrenheit range, and be 100% fine. obviously, the exhaust manifold and turbo is a LOT hotter than this, so measure this on the other side, under the intake manifold. also measure the temperature of the thermostat housing on the front left corner of the head, this is the coolant temp exiting the engine, and likely is also 210-220F or so when things are at full operating temperature. If its much OVER 220, *then* things may be running too hot.

if you want to verify the fan works, find and unplug the thermoswitch on the right (passenger) side of the radiator, and jumper the two pins of the plug together. AS I said before, the wires on this plug should be black and blue-black. Turn the ignition on (don't have to start the motor), and the fan should start immediately. if it does, your relay and fan motor are both good.

 

Alright, let's keep this simple. I simply wanted to know about the proper working condition of the fan, which Pierce answered for me. It wasn't a question of whether I was happy or not, but a question of the proper working condition of the fan. I have never seen it or heard it come on so I didn't know if this was normal. Now I know.Thanks for the help.

Thanks again. I'll check it this evening when I get home from work and report back. Again, the car has never gotten near the "hot" mark. Had it done so, I would definitely have shut it down. The needle climbs to the middle and doesn't move, for the most part. I just wasn't sure, due to my inexperience with Volvos, what was normal for this 1989 740 Wagon.

 

With a mechanical belt driven thermo fan the electric fan should never come on the way the system is wired. I believe the radiator mounted thermo sensor triggers at 225* or there about. I believe the design was based on the engine heating up when you turn on the AC and then the fan switch would turn on the e-fan. I have found when you convert to 134 you want to turn on the e-fan when you turn on the AC to make the AC more effective. I wired a relay in parallel hooked up to the low pressure switch on the receiver/drier. So when I turn on the AC the fan comes on and my AC system works great. Now to test the fan just jumper the switch in the radiator and it should turn on. Oh just to make sure turn the fan blade by hand to make sure it's not locked up. good luck

 

I jumped the two wires and the fan came on! I know it works now so I am good when I get the A/C fixed sometime this summer. I left it on when the car came up to temp to see if it really ran any cooler. It barely came down a needle width. I guess at this point I won't worry about it. It doesn't OH by any means and seems to be normal. I guess I could put in a cooler thermostat, but then I'd probably have emissions or fueling issues. Just going to leave it alone for now. Thanks again for the help!