Coolant flow to heater core ?

2001 4.0L XJ here. Does coolant flow through the heater core all the time, regardless of what the temp. control is set to? I only ask, because I know in my Ram there was a vacuum-operated shut-off valve that stopped coolant flow if it was set to cold, and would open a little more each time the temp. control was set warmer. I don't see a valve like that under the hood of my XJ, so I'm assuming coolant flows through the core all the time, unless there's something behind the firewall. Both heater hoses were hot today too, and I had the A/C set to cold.

Another question, not exactly related...the t-stat in my engine is the original one that came with it. Does it have the "burp" hole in it like the ones from the dealer do?

Anyone?

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Acording to my crappy Haynes manual (BTW-don't waste your $$...buy a factory service manual) there is no valve. It says: "Hot engine coolant is circulated through the heater core. When the heater mode is activated, a flap door opens to expose the heater box to the passenger compartment".

Can't comment on the t-stat question.



PS - 'Ya just gotta ignore the jerks on this board!!!

nosajwp said:

Anyone?

Click to expand...

My '95 XJ has a valve, it's above and to the rear of the oil filter. It's a plastic vacuum switch that manipulates a wire rod sticking out of the rectangular valve.

How do I know? The first time I changed the filter, I had to use a 3' pry bar to get it off, and in the process I broke the switch off of the valve casing. The next day, I didn't have heat. After I epoxied it back on, the heater worked great.