240 Would This be Possible on a '92 245????

Could I add an accurate ambient air temp gauge to my dash? If so, where would I put the sensor???

I live in Colorado and it's getting to be winter time, which means once the temp drops in the evening the roads behave differently.

Just a curious thing to add to my car to make it "mine".
The wife's S60 has one but I don't think it's very accurate.

It's late and I'm on my phone.....so No I did not do a search.

This is written with the assumption that you're going with the more common analog VDO ambient temperature gauge...

Sensor probe usually attaches to one of the bolts that holds the driver's front bumper shock to the front of the frame rail. Run the wire up behind the driver's headlamp and between the battery and the inner fender over to where the corrugated wiring harness tunnel is. Feed it through into the passenger compartment. Remove the knee bolster and route the wire up over the steering column over to one of the gauge spots next to the instrument cluster. Run another wire from fuse 12 or 13 to the same location. Run a third from a suitable grounding location, again to where you're going to install your ambient temp gauge. At the gauge and the fuse box, you want 1/4" female quick disconnect terminals. Add a short pigtail to the ground wire with another 1/4" disconnect terminal. That will go to the light bulb socket for the gauge. Finally, run a wire to one of the dash lighting bulb sockets, install a 1/4" female piggyback terminal on it and connect the brown wire to that, then attach it to that socket. On the other end, 1/4" terminal. That one will go to the other terminal of the light socket at the gauge.

Connect everything to the gauge, turn the key to run and make sure that the gauge is reading the ambient temperature. If it isn't, doublecheck your wiring and make sure that the bolt on the bumper shock plate is tightened all the way down. If that still doesn't do it, then it may be a bad gauge - I've seen that happen before. If everything checks out, slide the rubber gauge grippers into place, slide the gauge into those, and put your gauge bezel on. Reinstall the knee bolster and the fuse box cover door.

-J

There were both analog and digital ambient temp gauges available for 240's.

Here's the installation instructions.

Analog

Digital

John242Ti's instructions are very good. He's correct about the mounting position of the temperature sensor. The reason for mounting behind the bumper is to avoid engine bay heat and provide good clean airflow. The VDO analogue ATG kits are still available for ~$US120; I recently purchased a Fahrenheit version from them and it's excellent. See my article for details Volvo 240 Ambient Temperature Gauge.

Wasn’t there a “frost warning” led on some?

We'll my 95 940 has the little red led that lights up when it gets about 36 degrees f or lower on the digital outside temp gauge. Not sure about a 240.

2 old for this said:

Wasn?t there a ?frost warning? led on some?

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All of the Volvo accessory gauges for the 240 have the frost warning red LED. Well, at least for the 81- dash, not sure about the -80 one, I've only seen a couple of those and never looked closely. The light comes on a few degrees above freezing and goes off a few degrees below. On the analog gauges it is just a red led that is on all the time and it shines through a window in the needle assembly for the right temp range. On the digital gauges it is the little window in the middle and turns on and off.
The aftermarket analog VDO I have somewhere also uses the same frost warning led through a window in the needle cover.
Basic operation is the same as it was in later cars (through at least the P2), just separate instead of integrated in the instrument cluster info switch feature.

As far as the gauge accuracy goes I have been fairly confident that mine are close enough over the decades. Accurate? Probably not. Close enough to use as a good indicator that your wipers might be frozen to the windshield and you should look for ice on the roads? Absolutely. And even behind the bumper they pick up some engine bay heat if you sit still long enough, which just makes a summer day without ac feel hotter.

sbabbs said:

We'll my 95 940 has the little red led that lights up when it gets about 36 degrees f or lower on the digital outside temp gauge. Not sure about a 240.

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All of them have it. Not sure about the earlier 700 gauges, though. But, yes, all 100/200 series ambient temp gauges have the LED. Analog have the LED that's on all the time, but get uncovered by a crescent moon-shaped slot. The rest have the LED that turns on and off.