Bad rad causing cold winter running temps?

1990 I6, AUTO, AC, 3:55 w 31's

My cooling system was barely making due this past summer so I'm planning on replacing my rad/hoses/thermostat this spring (rads probably clogged...fins are shot, hoses are old...probably collapsing, thermostat is new OEM).

...this winter I noticed that it's taking a long time to heat up...if it does at all, even with the rad blocked by cardboard. After a 15min highway drive my temp is only running around 90-95C max. But it will usually spike back down at slow speeds to 75-80C. It would spike in the summer too between 85-105C.

Temperatures here fluctuate between -30C and +5C on average throughout the winter (windchill this week has been -45C).

Could a clogged rad or collapsing hoses possibly cause a cold condition in the winter??

On a positive note, it's been idling great, thanks to everyone here's help.

Sounds more like a thermostat is stuck open.

Restrictions in the cooling system, whether from collapsing hoses, clogged cores, etc. will slow down heat transfer, making it run hotter.

'nother note.... if you're still running the original viscous clutch. consider replacing it. It's probably not working well, although your highway/stopped symptoms are kind of backwards for a failed clutch. Normally, when the clutch fails, it heats up at idle, and begins to cool off in motion.

That's weird, if that's what the symptoms point towards, cause I replaced the clutch fan and OEM thermostat just this past July.

I should add, the highway/stopped symptoms are not always consistent. Somedays it will heat up when stopped (moreso in summer). I really hope it all goes away this spring with the new rad/hoses.

It can pretty much be only a thermostat problem if it won't warm up. You can test the thermostat in a pan of water on the kitchen stove pretty easily or just put another one in. It should be open shortly before the water boils unless you live at 10,000 feet.