Hello All:

I'm having a weird overheating issue with my 92 240 Wagon. It seems to overheat when the interior fan is turned on and the climate control "slider" is in the cold position and I'm driving around the city. At highway speeds everything is OK. It doesn't matter if the A/C compressor is on or off. The A/C works and is ice cold. I have replaced the following: Radiator, the water pump , and the fan clutch-upgrading to the tropical version. I have also confirmed that the auxiliary fan behind the grill comes on and runs as it should. Any ideas would be greatly appreciated. I'm at a loss at this point. Thanks very much.

Thank you all for the suggestions. I will bypass the temp compensation board and take temperature measurements with an infrared thermometer and let you know the results. As far as the coolant sensor is concerned, does anyone know where that is located? I didn't see one during all of the repairs I made.

The sensor is screwed into the engine block below the intake manifold and has a single yellow wire attached to it.

I had a similar situation - the temp reading on the dash was high and I changed a bunch of parts, and nothing fixed it.

I used an IR thermometer to measure the temp on the thermostat housing - it was normal so I knew there was another problem.

Turns out the coolant sensor I replaced was sending the wrong signal down the yellow wire. It was a new after-market brand, which I returned and told the supplier from where I got it. They gave me a new one, and it was still sending the wrong signal.

I worked with my local Volvo dealer to source a Volvo OE sensor, and that solved the problem.

Thanks.

Is it truly overheating or just running a little hot, reading higher than normal at times but not in the red zone? Are you going only by the gauge? No loss of coolant at the hoses clamps or anywhere? This would be pretty obvious.

You can use an IR thermometer to check the temp of the upper radiator hose. I forget what the normal reading is but someone here will know.

The temp comp bypass is a good idea in any event.


--
'80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

Hi,

Has the temperature gauge been modified by taking out the compensation board from inside the instrument cluster?
It causes wired readings when nothing is wrong.

The modification involves removing the cluster and taking the backside off. The complete board unplugs leaving five pins showing. You take a snip of small wire and jumper pins one and three together.
I soldered mine but you can make up slip on ends if you can find small terminals. That’s the hard part unless you buy a kit from IPD for like $10 with some instructions.
I have never gone that route and don’t know how good they are? Simple may have been kept simple?

Go here to see a real good explanation and the know how!
http://cleanflametrap.com/tempFaker.html


Phil

Thermostat ?

RonJ

Also new. Forgot to mention that in original post.

I have not done this. I guess I could but I get pretty consistent readings from the temp gauge until the fan is turned on. I would guess that if the compensation board was bad I would get weird readings at other times. I guess I should just do it to rule it out.

Hi again,

A overheating problem usually makes boiling and grumbling sounds after the engine is shut down.
If you haven’t heard that, then you are not overheating and it just might be the board sensing a signal that it’s just a little bit warmer.

The chip in the board moving in digital steps.
The circuit board does not know how to make smaller steps so it takes the next big up one!
It can move 1/4 of the range up that would be only the width of the needle normally!
This move is a bunch up and it scares or alarms people.

If it’s hotter and they know it hotter than usual outside, it stands to reason to pop eyebrows!
Interesting enough, This can happen even when it’s cooler outside.
Since you know that it’s cooler on the engine at the moment, you are curious, as too, what caused this and you say, “What the heck and go with weird!” (:-)

This is the to get rid of that thing and go with strictly analog. It will do this without it altogether.

I read that Volvo had earlier complaints with the gauge moving some when the engine was climbing hills or the introduction of more air conditioning units being demanded or sold.
This rattled some people into making “service” complaints.
This was suppose to be their fix this for those few that “expected” their cars to be a “State of an Art, invulnerable machines!”
These types are also within the BMW dreamers and Porsche fanatics crowd at heart!
More $$$$$ than other things!
Volvo has tried swooning those characters!
The newer cars are space capsules with wannabe astronauts for buyers!
It took awhile, but Volvo has gravitated to staying mainstream, for better or worse?

For me, an installation of a newer radio leaves my eyes glazing over! I read the manual to see so many features I have absolutely no need for!
Especially for another enhancement subscription for this or that service associated with a peripheral device!

Sorry, I don’t live in my cars, as of yet!
(:)

Phil