Dear Members,

After searching, reading, and fixing most of the issues on our 1993 300e 2.8, I have to now ask for guidance from the brain trust.

Without AC on, the temperature gauge is horizontal, ie. normal, 80 C. Temp holds steady, even in hot ambient temps.

With AC on, the temp climbs when slow in traffic or city driving.

New electric aux fans (both), they come on at low speed under thermal load of compressor. Jumping the connectors at the pressure switch also sets them on low speed. Jumping the high speed temp sensor also sets them on high speed, and they come on when temp climbs.

Replaced fan clutch as it overheats when in slow or stop and go traffic, no difference.

Water pump is less than 1 year old, changed due to leak.

New pressure cap and thermostat (behr)

New radiator-replaced due to crack

Compressor comes on and the low pressure side is in the blue zone on the gauge (25-35 psi). No funny noises from compressor, does not cut out, except when temps get excessive.

Bled coolant out of thermostat housing by loosening temp sensor, fluid flow, no bubbles.

Temperature climbs when AC is on, aux fans kick in, and temp still climbs to 110-115, at which time I freak, turn off AC and turn on heater to dump heat which is effective, but it seems as if it takes a considerable time to dump the excess heat. There are no bubbles in the coolant, no boiling in the reservoir, no loss of coolant. I am stumped, it is not even that warm outside. The fans suck air in through radiator, cleaned the condenser and air path when replaced aux fans and radiator. I am at a loss.

Thanks for your advice.

Martin Wolf