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2006 Infiniti G35 - Reluctant heat

On my G35 I have the problem with the heater fan not coming on for a long time. It has a sensor so no cold air from the heater could possibly bother a Infinity owner. It’s a ridiculous feature that is now going south on my car.Sometimes it might not come on for 30-45 minutes. Funny thing is driving on the highway at faster speeds seems to make it come on sooner. Anyone have an answer and a ballpark figure to fix or just move to Miami??

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Maybe one of the mechanics here will have a quick fix, but I’d step back and run down this list of common issues with heat. And check the coolant thermostat is operating properly.

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The vehicle may just need a new blower motor?

It’s old enough!


Ask your shop to measure the coolant temperature when the engine is fulled warmed, or at least after it has idled for 10-15 minutes after a cold start. A faulty engine cooling system thermostat is a pretty common problem by the reports we get here. The the thermostat is supposed to stay completely closed until the set point is reached. But over time the sealing surfaces begin to show wear and it begins to fail to seal properly, which causes lower than desired coolant operating temps. If the coolant is too cold there’s no heat to go around for the passenger compartment heaters.


Temp sensor could be flaky.

The thermostat,water level and all else are fine. It never over heats and once the heat finally kicks on it works like it should. Fan works fine,defroster and lots of hot air until the system cools it down somewhat depending upon the temp selected. It’s in a sensor or computer that is slowly malfunctioning. Right in the owners manual it tells you the fan will not come on for up to a couple of minutes upon start up on a cold day and that’s what it used to do. Now it’s coming on later and later IF it ever comes on.

How did you determine this?

Are you in an area where it’s extremely cold? I’m wondering if it’s possible that it’s so cold that your engine is struggling to get the coolant hot enough to produce heat in the cabin

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I will check the water level again (just done at my oil change place a month or so ago) and see if it needs any but I doubt it. But it’s worth the look see. But…I know these have a temp sensor tied to the heater fan,it’s clearly stated in the OM but it states about two min is the max wait for the fan to come on.

BTW…once the fan does come on there is plenty of hot to very hot air,it’s never blowing cool or luke warm air. That is IF it comes on. I’ve also seen it kick on and really warm up the interior and then make a stop for gas for just a few minutes and it again will not come on even though the engine is at operating temp.

I would also ask the question of how the thermostat was determined to be OK as @pyrolord314 had mentioned.

Reading your response I believe that you may not fully understand what Pyro was talking about. He is ( I believe) speaking of the engines thermostat… A wax filled spring loaded conglomeration of a device that regulates engine temp and warmup time.

The engine also has a temp sensor as well… When a T stat gets up there in years what can happen is that is no longer operates as quickly or as uniformly as it did as a younger/newer component.

This is a very solid and inexpensive area to start with… I would be looking toward the T stat far before anything else honestly… Its basically your first stop… the second stop would be the engines temp sensor itself for the same, yet different reasons.

If you really wanted to split hairs you can buy an IR thermometer and do measurements…however you have nothing to compare those to because your vehicle and those components may no longer be operating in their normal modes…so the readings you get will be the failure mode readings. Hell any good OBDII scanner will show you what temp the engines temp sensor thinks it is and when… but again…these readings will be w the suspect components you have currently.

I’d do the T stat first and then see what you get…then the temp sensor…

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To check for a bad blower motor, turn the ignition on, set the blower speed on high, and reach under the passenger side of the dash and rap on the blower motor with the handle of a screwdriver.

If the blower starts working the blower motor requires replacement.


Or this vehicles multi speed controller for the blower motor lost its ability to run at its slowest speed so thusly it sort of skips it (the delay) when in actuality its trying or thinking that it is running the blower motor. Then again the blower motor may run at a pre-selected (by operator) speed that is not the slowest setting.

There’s a few places this issue could stem from now that I’m thinking about it and all the electronics in between more…but alas…I’m a simpleton so I try to start with simple.