My 1990 240 DL was overheating when I turned on the AC. I checked Brickboard (of course) and I followed the advice of one who said to hose out the crud that had accumulated in the radiator. Following the advice of another, I checked and determined that my radiator is metal. The first solution worked. The engine remained near normal for about a week. Today, the ambient temp was around 93 degrees. The engine remained cool for 80% of a 10 mile, one hour drive in stop-and-go traffic. Suddenly, the temp gauge shot to the orange region, forcing me off the road until the engine cooled again.

I've heard some talk about an AC Relay, but I don't know what it looks like or where to find it. Nor do I see any reference to it in the Chilton's guide for my model and year. Any suggestions? If it is more convenient, you can email me directly at franklinparrish@comcast.net

Thanks in advance for your help.

Franklin Parrish
Dreading August

Franklin I also have a 1990 240DL. My car does not have the electric fan everyone is talking about. It did overheat everytime I used the AC. The problem was the factory thermostat. It had separated into 2 pieces! Change the thermostat first, it may just solve all your problems with very little work or expense.

Fan clutches, as Matt said, can cause that. For some stupid reason, they'll work sometimes, and not work well at other times.

However, the fact that you said the temp stayed normal, but THEN shot up, suggests either a sticking thermostat, a slipping water pump belt (or impeller) or a faulty gauge. The gauge circuitry is notorious for showing a random overheat condition when in fact there is none. Giving the gauge a good whack with the palm of your hand (not a smashing one, just a slap) usually brings it back into line, if the gauge issue is the problem.
--
1992 940 wagon, 72k
make people envious; smile often.

Chris, you were right. The guage was sticking. I saw it start to rise and then gave the dashboard a whak like you said. It popped back down, and everything has been fine since. Now the next logical question is this: Is that condition caused by the guage or the thermostat? Do I need to replace both?

Slipping fan belt.
Bad thermostat(not opening)
clogged radiator
Clogged condenser
bad water pump
engine off time.
bad clutch fan
bad coolant(improper mix)

As I understand it, any of the above could cause overheating. There are probably others. Just my 2 cent.

Lawrence

Dont forget malfunctioning temp guage(make sure the engine is actually overheating)

I had an a/c compressor sieze on a mazda once. Stopped the engine dead. Im just wondering if, perhaps, an a/c comp going bad could exert the king of load to cause overheating? Just a question. Might as well consider all angles. You did say it was with the a/c on? Might be a dumb question, but, oh well.

Lawrence

Did you determine that the radiator core is metal (which they all are) or did you determine that the tanks on the side are metal? If you have already flushed the radiator fins, then it sounds to me like a classic case of mineral deposits or other crud clogging up the radiator from the inside.

You should also check to make sure the fan clutch is working properly.

--
Matt L. -- Cary, NC -- '89 740 sedan -- '91 740 wagon

Oh, and Matt, where would I find the AC Relay?

the relay will be right near the coil. and another thing to check is while the car is on and the A/C is turned on, does the electric fan ever come on... it is right in front of the radiator. I had the same problem a few days ago and ended up having a bad solder joint in the relay, so i resoldered it and everthing was workin again.

kevin

So would a radiator flush be my next step? Can I determine if the fan clutch is working properly or is that a service call?

Crank the car in park and turn on the air. The electric fan in front of the radiator should cycle on and off as needed to maintain proper temperature. Had the same problem on a 91 240, fan was bad. Instead of spending the $ for a new Volvo fan, I went to a radiator shop and bought a used one that looked close (pusher type, brand?) and adapted it to my car. 3 years and works good.