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?