OK, next question:

On the right top side of my radiator, facing back towards the engine, there is what appears to me to be a thermal switch. You can see it here:

http://picasaweb.google.com/Lanval.de.logres/RadiatorSwitchAndFan

I assumed initially that it was attached to the forward fan - but it's not. You can just see the wiring for the fan taking off into the car in the lower right-hand corner of the picture.

I never use the A/C (and it doesn't work after I had it fixed last year) so I don't really know if the fan works. I'll test it in the near future, but here's where this is all going:

I'm going to do the E-fan conversion - I've read numerous threads here on the pros/cons, so let's just say I'm going forward with it anyway. I have the nice relay from the donor car which runs the fan on high or low; my question is this:

Is the switch in the radiator a thermal switch that could be used for that? Is there any way to tell? I looked all around on the switch (except the underside, which is a bit difficult to get to until I buy one of those cool little mirrors) and couldn't find any markings...

So now I defer to the collective wisdom of the BB - I thank you in advance for your assistance.

Best,

Lanval

My 90 745 with B230F Regina has that same sensor. Top, passenger side facing firewall, right?
When I placed a jumper between the two leads that run to it, my electric fan kicks on. Whether or not my A/C, or engine for that matter, was running. so it probably switches the relay you have. Hope that helps.
Which raises a question of my own. Is my car supposed to have a belt-driven fan AND an electric one? Because it does. (it all looks original) It's my first Volvo.

I'm not sure about the 200 series, but on my 1987 740, I was trying to get my fan working. After no luck I gave up and 7 months later I'm going through the fuse panel and see it has its own fuse. And it's blown!

Don't forget the fuses amigo.

Jamie

Jamie,

Thanks for the timely reminder. I'm going to take a look at that fan tomorrow.

Best,

Lanval
--
92 240GL - Virgos, IPD 25/25 sways, 150,000 mi strong

Yes it's a fan switch, but it will come on at too high a temp for an E fan conversion. Luckily, that's a screw in on an aftermarket radiator, so if you dig around www.thepartsbin.com, and look at some early to mid 80s audi 5000 fan switches, there are a few in the temp range that you need that will thread right in.
--
-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '92 Ford F350 diesel dually

The switch you are describing controls the auxiliary fan in front of the radiator. It does not control it directly, but via a relay, which is why the wires do not appear to be connected. In theory, you could use this switch for an electric fan, but it may not be suitable, as it doesn't turn on until things get pretty warm. As for finding a replacement switch of the correct heat range (for what you want to do) that fits that hole in the radiator, I have no idea.

Some years of Saab 900 (mid 80s) had a metal tube about 4 inches long with a threaded hole in the side of it that takes a standard large brass thermoswitch (readily available in several different heat ranges) This tube was mounted in the upper radiator hose. I would try to find one of these, or something like it.

Blue Horse, Is there some kind of wiring on the inside that I'm not seeing? I think you're right from everything I've read, but I'm wondering how the relay is connected to the switch - the switch just has two prongs sticking out... Thanks, Lanval

Update on this: I looked at the Bentley and the Haynes - for once the Haynes worked. According to the Haynes, the switch for the AC fan is a "T" in the line from the Engine to the Radiator which enters the radiator at the bottom right location up to 1990.

From 1991 on the switch is in a similar location right in front of the expansion pipe for the AC system. This runs low along the passenger side.

As far as I can tell, the switch I pictured is not the switch for the fan. I'll check the AC line for the switch tomorrow or Thursday, since I want to know if the accessory fan is working - but that still leaves me wondering if that switch will work for the efan.

Thanks,

Lanval

The switch in the upper right radiator tank is the aux. fan thermal switch. It's meant to turn that fan on when excessively high rad temps are detected. Factory wiring diagrams I have, and my junkyard observations, show that a relay feeds power to the rad switch, and that switch is connected directly to the fan. This puzzles me a little, as I would have used the switch to trigger the relay, so the switch handled only control current, and the relay did the heavy lifting. Volvo thought otherwise, possibly because it requires less wiring runs their way.

I have pulled and tested a few of these Volvo rad switches; they all close (switch on) at about 93C and open at around 88. That varies by one or two degrees C, but the "open" temp is pretty consistently 5C below the close point.

SAAB switches can be found in the upper and sometimes lower (cold return) rad hoses. (Good luck finding one that is not badly corroded with the switch assembly rust-welded to the tube!) The upper ones operate at close to the Volvo temps above. The lower hose units operate at ~10C lower temp. for both events. But note that the SAAB upper hose unit is seeing coolant temps immediately after the liquid leaves the engine, where the Volvo switches are located across the radiator from the engine (upper) hose, so the coolant will have dropped a bit of temp before hitting the switch. IE: the engine will be hotter before triggering the rad switch than a switch in the upper hose. The Volvo switch is meant to activate that supplementary fan when things get uncomfortably above the thermostat rating, and not act as the primary cooling switch - which is what the SAAB does.
--
Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)

Volvo Dad,

As a double-check, is the lower switch the AC pressure switch (i.e. it turns on the fan when the AC system is above X pressure) whereas the switch I pictured is a thermal switch which operates separately from the pressure switch? Ah, I think I got it now...

So, can I use those prongs on the thermal switch, since they're not connected to anything?

The reason I ask is that the temps seem within range; here's a link over to turbobricks where someone scanned a documentation page on the 940/60 efan:

http://forums.turbobricks.com/showthread.php?t=96739

Note that the fan on the 940 isn't running below 102C; from 102C to 114C it's running at half-speed; from 115C above the fan is running at full-speed.

So this poses a number of questions:
1) Any reason I can't use the switch since it's set lower than the original 940 range?

2) Is the 940 engine significantly more efficient at cooling? I note the radiator in the 940 is said to be bigger, because the fan shroud from the 940 needs to be cut down for the 240...

Note - I have the denso 100 amp alt installed, courtesy of the same car that gave up the fan!

Thanks all!

Lanval

OK - this is a 940 fan setup? Late 940's differed from the 240/740 system in that the relay supplies the power directly to the fan. I have the Bosch LH 2.4 on my 940...the fan relay (runs the fan at low or full speed) is triggered by a signal from the ECU, which in turn gets info from the engine's ECT sensor. I believe the Rex/Regina systems used the rad switch, as their ECU's did not have the capability to run the fan.

There is no switch in my rad - just a plug in the hole. (..and the hole is not threaded, so I have safety wired the plug in place). The "lower" switch(s) you mention are presumably the A/C pressure switches - they also can turn the fan on.

940 engines are essentially the same as the 240...114BHP NA or ~160BHP turbo, so the cooling demands should be the same or very close. The bigger rad and fan was probably just a design change to improve cooling and get Volvo's A/C performance up to standard.

In your case, I'd wire the switch to turn the fan on to low speed, and I'd bypass the temp gauge compensation circuit so the gauge was telling the real story. If you get signs of overheating, wire the switch to the relay's high speed input.

Looking at your photo, it looks like a dual-trigger switch from a 90's VW Golf/Jetta would fit. These switches have three terminals - one is common, (power or ground, your choice), and one of the remaining ones shorts to it at 95C, the other at 105C. That would work well with the 940 dual-speed fan relay.
--
Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)

VolvoDad,

Thanks - between you and the diagram over at turbobricks, I've got the 940 system. Here's the relay that I pulled for the fan:

http://picasaweb.google.com/Lanval.de.logres/RadiatorSwitchAndFan

(it's the 3rd pic)

The missing plug in the relay is the one that is actually on the fan (and I have it). So the two wires in the middle (marked "in") came from the ECU which is measuring the ECT (which I'm assuming is Engine Coolant Temp.) The single large red wire is power - can I assume that needs to be run to a fuse somewhere? Should I wire direct to the battery, with 30amp fuse to protect from death/destruction? (note I'm going to my Bentley now to see if there's a fuse somewhere that's dedicated to such functions - or available, anyway). Thoughts on power source?

I'll make this leap - if the switch on my radiator is working, then I need to run power OR ground to the 'common' prong, and figure out which is the low temp prong, and wire that to '1' on the 'in' relay connector.

Then power to the relay (fused) and then plug in the fan.

I'll add, I'm thinking of just saying the hell with the switch on the radiator, and just wiring it so that half-speed is always on, with an in-dash switch for high speed.

Finally, in one post on this subject, the poster mentioned using the delay circuit/diode/electric-whose-name-I-can't-remember from the dome light to make a delay so that the fan wasn't constantly cycling on/off, in stop-and-go traffic for example. Is this necessary with the denso 100 alt amp? Can such thing be purchases at Fry's or Radio Shack - or should I grab a dome light circuit tomorrow at the JY?

BTW, my temp gauge is jumped so I have real coolant temp, and also have engine oil temp gauge.

Thanks all for the input, and a specially big thanks to VolvoDad.

Best,

Lanval
--
92 240GL - Virgos, IPD 25/25 sways, 150,000 mi strong

Judging from your pics, you seem to have about everything I used for my electric fan conversion, except for the 940 fan and shroud. Since I didn't have the puller fan for the AC on my car, I concluded that I had a universal replacement radiator designed to go either on a 200 or a 700 series, which is why I had the hole for the thermal switch. The switch I used came from a mid 80's Saab 900. I don't recall it's thermal range. And I note that you have the dual relay from a 900 series (same part is used in an 850). You should grab the original fan power wire from a 950, as well, complete with fusible link. That way, you can wire the whole thing directly to the accessory wire from the battery, and not have to worry about blown fuses or any other connections.

The post you're referring to about the delay circuit probably came from Sven's Maintainer, right? My system is loosely based on his. The high speed side of the fan relay is wired to the thermal switch, but the low speed side is wired to (get this...) the brake light switch. if you're not moving, there's no air going through the radiator, so it's nice to have the fan come on with the brakes. As for the delay circuit, you just wire the capacitor from the dome light circuit inline with the wiring from the brake light. Anyone who's ever owned a car old enough to have a mechanical coolant temperature gauge with a capillary tube knows that the coolant temp surges when you shut off the car, and the coolant stops circulating. I don't know how much good 9 seconds of slow speed radiator fan running really does, but it makes me feel good. :-)

By the way, as far as pros and cons, I haven't noticed any wholesale increase in horsepower or decrease in noise. But I'd never go back to a mechanical fan. Why not? I love being able to change my timing belt without having to remove the fan and shroud!

-EdM.
--
'90 240DL Wagon 'Lola' -- '72 1800ES 'Galadriel'

Ed,

I've got the fan and complete shroud too, though not the full power line. I put in the wiring for the fog lights today, so I'll be doing the fan tomorrow.

I do have an inline 30 amp glass fuse for the power line... is that enough? I don't know what fusible links really are, though I can guess their function. How, roughly, do they work (I can research the details elsewhere - just looking for a thumbnail sketch here), and is it a better choice than a regular fuse? I used an in-line mini-fuse (30 amp) for the foglights, and it didn't blow immediately, so I'm assuming it's OK (though, to be fair, I was only ever running one light at a time... couldn't get my hands on a dual 87, so I used an 87/87a dimmer relay to verify function (Pep Wieners didn't even know what I was asking for - off to NAPA tomorrow).

My auxiliary fan is dead too (checked today) so it's also coming out, and relatively soon, so is all the AC stuff. I'm going to fix the AC in our Caddy, which I'll bet works better than any AC system ever produced by the Swedes.

I've gone back and forth about using the switch on the radiator, plus the 940 relay. I've got the stuff to do a dual manual switch set-up, and control the speed myself. This has both positive and negative values:

Positive:
absolute control
ability to proactively prevent overheating
maximum flexibility (off, low, high)

Negative:
Don't forget to turn the fan on, for the love of God!

I'll think about it more tonight, and decide by tomorrow.

Best,

Lanval

Addendum -


I forgot to add that the only reason I'm doing this, is, like yourself, to enable access to the front of the engine for visibility, changing of t-belt, etc. Couldn't care less if it gives/takes a couple of horsepower - that's not an issue, whereas changing the T-belt is.

I'll post when I get it in, and working.

Best,

Lanval

That relay operates by grounding the signal input wires - that's what the ECU does in response to the temperature it "sees" from the ECT. In my 940 the relay's power (Red) wire is connected directly to the battery through a fusible link. sunstitute a 30 or 40 Amp fuse and it should work OK.

It looks in my Green Book that the BL-SB wire triggers low speed, and the W-SB is for high speed. Bench test to be sure.

An earlier post had some words of wisdom - the location of the rad switch may still allow things to get too hot before starting the fan. Even if you install the dual temp. VW/Audi switch, its low temp doesn't switch on until about 93C. In the VW's that switch is located in the inlet rad tank, but down low, well below the inlet hose. Still, I'd guess that's a hotter location than you have in the Volvo.

That's the challege in fitting an electric fan to the 240 as the ONLY fan - how do you locate and wire a sensor so that A) the engine does not overheat; B) the fan and thermostat are not fighting each other. You'll need a temp gauge that works right and some time experimenting.

As for too much cycling of the fan - not sure I'd trust the various ideas on delay mechanisms on such a critical system. The fan on my 940 rarely comes on unless AC is in use, and does not cycle much - but then it's bone stock as the Swedes designed it.

--
Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)

That is indeed the thermal A/C fan switch. It is only used if the car came with the Aux outer fan. There is a relay on the left inner fender, I think, but not real sure. Check your Bentley and you will find it. There are several archives on the subject along with pics. Oh yea, almost forgot,,the thermal switch you are talking about has a tendency to pop out.. I have seen nylon ties used to keep them in..As Willey Nelson said,,,,..never mind he forgot...
--
Max..1989 244 DL 5 Spd., V15 Phase II Cam Bilstein HD, Turbo Swaybars, Poly Bushings all round, Turbo Wheels, Black leather interior, Electric mirrors, LED dash and gauge lights and now NEW ECODES with the turn signals, 1992 black 244 next project