My mostly trusty '90 wagon has an intermittant no heat problem. The engine won't heat up normally and when it does heat up at all, turning on the heater blower brings the gauge down to C. Just going down hills can cause it to start cooling off. I have replaced the thermostat 3 times, it has a new radiator, waterpump, cap and the cooling system has been flushed. All these things have made no change.

There is no air in the system and it doesn't mix oil and coolant. The upper radiator hose is hot but the lower one is just barely warm when the problem occurs. The heater control knob is active. Right now I have a piece of cardboard over the complete radiator ( 3"x 3") hole in the center and it doesn't even come close to overheating. The gauge is accurate but doesn't quite go to the "normal" point, it's always towards cold by 1/16". Under no conditions will the cooling fans come on, even when indoors, reving at 3k for 10 minutes. An infrared detector show the upper hose temp at 170 and the lower at 90.

My mechanic w/30 years of experience says that he's only seen overcooling once before and he didn't solve it

There is a post on this forum with the same problem but no real solution: [URL=http:// https://www.honda-acura.net/forums/showthread.php?p=1587375#post1587375]

Winter here in the northeast doesn't plan on leaving soon...any help would be more that appreciated. Thanks.