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SL320 Heating Problems

4785 Views 16 Replies 4 Participants Last post by  kiorash
Greetings Folks,

As the title suggests - My 1996 SL 320 is taking too long to kick in the heater from cold start. Sometimes up to 20 minutes. This was ok in the summer but come winter I will find this extremely painful.

Tried a search here and other forums but there is not much on heating issues. Any ideas or pointers will be appreciated. Hoping to get this sorted myself.

many thanks:surrender:
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There is also a coolant circulation pump (M13) which is located under the Mono-valve (Y19), difficult to see as the mono-valve is in the way. The pump is used when the engine speed is low and also for REST heating mode when the engine is not running.
You will get a AIRCO B1416 code from the scanner if that pump is not functioning. But it is not fatal as it just takes longer to warm up and the REST mode may not work.
The thermostat is at the water pump at the from of the engine.
The mono-valve is near the windshield wiper and cabin air filter area.
The coolant circulation pump (M13) is beneath the mono-valve (this is not the water pump).
Just do it with a cold engine, may be remove the cap on the tank to release any pressure, then unbolt the top and replace the thermostat.
Then just replenish any lost coolant.
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