camhabib

So this was a fun one to wake up to with an outside temp of 18F this morning but, I have no heat in the car. Fan blows fine, thermostat controls the air temp from cool to arctic chill, but even at the HI setting, the air is cool at best. I understand this is a somewhat common issue with the new 991's, but I have yet to hear of this happening in a 997, and can't really think of what it might be. Any ideas or quick things I can check before I bring it in to get looked at? Thanks!

namronorman

What did your water temp and oil temp get to before you stopped driving?

camhabib

All temps were normal as far as oil and coolant. Drive was over an hour so more than long enough to get things warmed up. I even threw it in to Sport+ for a bit to see if maybe things just weren't warmed up enough (it was a particularly cold morning), but no change aside from a rise in oil temp to well within spec.

jhbrennan

Sounds like something is stuck closed since the car is generating heat. Cycle all the buttons including the defrost button - maybe this will "unstick" whatever the problem is. Defrost should send a lot of heat to the front windshield.

camhabib

Tried that. Cycled the a/c, recycle, defrost, vents, etc. Tried restarting the car and didn't help either. It blows plenty of air, it's just cool, maybe 1 or 2 degrees above ambient.

Appreciate the comments so far!

semicycler

Check your coolant levels. Other brands of cars can lose interior heat with low coolant.

I've also seen it when there is too much distilled water in the radiators instead of the proper 50/50 mix. The weather drops well below freezing and something gets stuck. It usually clears iteself when the car warms up though. Any chance you can park in a garage for a few hours where ambient temps are above freezing?

camhabib

Checked coolant levels, they were a hair low, but still plenty left in reservoir. I'll pick up some more coolant and top it off later today just in case. Car is parked in heated garage, so everything should have been fairly warmed up, but it's certainly possible something still got stuck shut when it hit the cold air.

Philster

If the car runs fine, and you are sure about the coolant level, as well as the temps, then you can consider whether the heater core is clogged... and maybe the coolant is in need of flushing/changing.

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Wayne Smith

Check your thermostat. If that is stuck open the coolant will favor the motor rather than the heater core.

camhabib

Any idea on how to check if either of these is the cause of the issue?

Buddhamonk

if heater core or heater core hoses are plugged, it's usually because of air in the system. Would start by either bleeding the radiator or just doing a coolant flush

If engine is warming up as normal and not overheating, it's unlikely to be a thermostat issue

user 72902

997's have independent coolant lines that run to the heater core and a primary set that run to the radiators. The thermostat controls flow to the radiators. Its possible that the heater core is obstructed which limits your heat. However, I'd first look for a stuck vent flap in the dash.

Wayne Smith

Thanks for the correction.

camhabib

Just a quick update for anyone following along. I spent a few minutes earlier today playing around with the thermostat. Heard a flap close pretty abruptly after changing the temp between max and min a few times and like magic, the heat started to work again. Seems like the flap was stuck shut for some reason, perhaps from being set at the same temperature for a while. Thanks again for everyone that provided help!