I have a 1991 240 purchased one year ago with 160K miles. When stuck in traffic with the A/C on, the temp gauge suddenly spikes after about 5 minutes (I have not yet bypassed the compensation board). Turning the A/C off brings the temp back to normal within one minute, as does moving at least 20 MPH with the A/C on. Without use of the A/C, the temp gauge always stays put at the mid-point.

I have owned several 240s, but this is the first equipped with an electric cooling fan. The electric fan was DOA and I removed it.

I have replaced the thermostat and water pump, flushed the cooling system and replaced the coolant, tried another (used) fan clutch, and sprayed out the radiator from the fan side. No change. When replacing the coolant, there were thick green deposits in the reservoir that almost peeled off in sheets. The radiator appears original.

Is the problem likely to be the result of the missing electric fan, or a partially blocked radiator? If the radiator is marginal, I’d rather replace it than nurse it along by installing a new electric fan.

If the cooling system is in top working order, is the electric fan needed? Was this overkill on the part of Volvo, or an integral part of the cooling system design on some 240s?

Shortly after moving from CT to Phoenix area, I noticed the temp needle hitting the red zone if I was in traffic with the AC going. I had already bypassed the pressure switch, so the aux fan would run whenever the AC was on. After a number of checks I decided to replace the radiator, and that fixed the overheat ptoblem. I just got an OEM style from fcpgroton.

The aux fan is just an extra help for the condensor... basic engine cooling should work fine without it, which is why I think your radiator is the culprit.

You need to cooling fan. Your air will work more efficiently and you won't overheat the engine. My 740 with 2 year old radiator, new hoses, new water pump and new thermostat overheated last week and stalled because the condenser/cooling fan was not running.

They are expensive, but check on ebay.

I also wonder if someone tried to use a solution to stop a leak and that is why you have goodies in you coolant. That may be clogging the radiator a bit. If it's original and you have the coin, I'd change the radiator while your doing the fan.

Gary

A junker would be a less expensive source for the part.
It was only included in newer 240's.
A study of fcpgroton.com will tell you which years had it.
This should also tell you if the 740s used the same one.