1979 300SD Diesel Heating Solution

Hello,
I have a 1979 300SD 5 cylinder diesel in awesome shape. I just started having a heating problem and I had the cracked thermostat replaced. Last summer the thermostat ran at about 40-50c and now its running at
90 degrees.
The fan in front of the radiator isn't coming on. The air conditioning blast out cold and the heat blasts out heat.
Is the fan supposed to run at all times? If yes, what should we be looking for as the cause for the fan not running?
I am also looking for a mechanic in the east end of Toronto.
Thanks Judy
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Your running temp of 90 is normal. The aux fan is supposed to come on when AC is on... check the fuse first.
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The electric fan in front of the radiator, a/k/a auxiliary fan, runs on demand. The important thing is that the engine temperature be at 80+ degrees C, rising to say, 100 degrees C, when pulling up long grades. Incidently, the device you called the "cracked thermostat" is the much cursed climate control "servo".
I've owned an '80 300SD since new and agree it's a fine car. Mine now has a digital retrofit climate control system in place of the "servo" etc. - my concession to technology.
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On May 15, 12:35 pm, "-->> T.G. Lambach <<--" <"T.G. Lambach at NoHamorSpamcomcast.net"> wrote:

And that demand comes from either the engine coolant temp going above a certain temp or the freon temp at the receiver/dryer going over a certain temp. So, if it's a very hot day, you may see it come on for the AC or the coolant. The coolant triping it can usually be seen after some hard driving on a high 80s or above day, followed by letting it idle for a bit.
The important thing is that the engine temperature be at 80+

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