Heater failure

[Brikkhouse]

Hey y'all

When I start my 2007 M35x the heater does not turn on until I drive for quite sometime or not at all. What can I do to fix this problem.

[Jagpaw83]

Have you had any work done recently?

[Brikkhouse]

No work other than an oil change

[svard75]

Is the climate control panel functioning? It typically takes a few minutes for the heater starts blowing. Once it's warm enough the blower gradually starts increasing. Does the blower start?

[Brikkhouse]

Yes my panel works. I will have it on high for more than 10 mins and I hear no blowing air cold or hot. After several mins air will start to come through my vents. I don't think it's a problem with my car being cold because air should still blow it would just be cold. It is pretty strange!

[svard75]

Is the engine overheating? Check the water pump and accessory belt.
Is the AC working if you set the temp to the lowest setting?
We have an ambient temperature sensor hidden behind the front bumper which could be malfunctioning. It's on the drivers side just above the fog light and looks like a little bulb. Remove the connector and test the leads using a multimeter. It should change resistance depending on temperature. That's all I can think of.

[The00Dustin]

Yes my panel works. I will have it on high for more than 10 mins and I hear no blowing air cold or hot. After several mins air will start to come through my vents. I don't think it's a problem with my car being cold because air should still blow it would just be cold. It is pretty strange!

Do you have the temp on high or the fan on high? If the auto light is on, the fan won't blow until the engine warms up because you want heat. If the auto light is off and the fan is actually set all the way up but not blowing, then that is likely an electronic problem, so I've got nothing either.

[gmoney35s]

I have a similar problem when I go to warm my car up even after the car has reached regular operating temp the air still blows cold until I drive it when I stop to run into Starbucks or something even leaving the car on the heat goes cold until I start driving

[The00Dustin]

I have a similar problem when I go to warm my car up even after the car has reached regular operating temp the air still blows cold until I drive it when I stop to run into Starbucks or something even leaving the car on the heat goes cold until I start driving

His problem is the fan doesn't blow. Your problem is you are low on coolant or there is a bubble in your radiator.

[lovemycarM35]

I would start by replacing the blower motor I belieave there is a sticky on it not much work at all

[raddish1000]

Did you ever resolve the problem? I have a 2006 M35 and have the same (sounding) thing. Well after the engine is warmed up, I get cool-cold air coming thru the vents (fan works fine) for 10-15 min, even when the T setting is adjusted up to say 80F. Seems like it's either a sensor issue, or maybe an intermittently stuck actuator that operates some sort of vent or baffle that controls whether air is routed to the heat exchanger? The heat eventually comes on, but its rather chilly for quite awhile!
Anyone know of Service Bulletins on this?

[The00Dustin]

raddish1000, does your heat get cold at stoplights, too? If it does, and perhaps even if it doesn't, you should check your coolant levels. If the coolant is low and, as such, not circulating like it should, then the heat exchanger will have cold coolant in it. I'm not sure how the system "knows" the exchanger is warm and it's OK to start blowing on automatic, but it's possible that there isn't a sensor just for that and you are just low on coolant.

[svard75]

Our cars have so many electronics with the auto HVAC you'll have to perform some work to find the culprit.

First start with the basics and the easiest of checks.

Engine Coolant Levels
Check coolant level in the overflow bottle. If it's empty then you should check the coolant level within the radiator before filling the overflow bottle. Take the engine side covers off, remove the front air diffuser to air filter box, remove the rad cap, if cool, and allow coolant pressure to release. Open and check to see if you can see the coolant level (It should be right up to the top of the radiator. Also check If the rubber seal on the rad cap contains white chalky stuff, replace the rad cap if yes (I would consider a coolant system flush if you notice this white chalky stuff because that's calcium deposits and enough of those will cause blockage and poor circulation). Fill the rad to the top and tighten the new rad cap. Fill the coolant overflow bottle to the min line and run the engine to NOT. Watch the level in the overflow bottle. If it remains the same then continue to leave the engine running with the internal temps set to maximum. Watch the coolant level and fill as required. Make sure you use the Nissan spec coolant only.

Thermostat
If the thermostat is frozen open then coolant is always circulating through the radiator even when the engine is cold. This prevents the coolant from reaching NOT. The Heater core circuit is not directly impacted by the thermostats operation, however it does circulate the coolant from the engine side of the thermostat. Check the engine temps after idling the car for 10 minutes, it should reach just under the half way mark. (Please make sure you are doing this outside in a well ventilated area)

Ambient Temperature Sensor
Mounted to the right side of the radiator is a small bulb shaped sensor which is the ambient temperature sensor. This is a thermistor that sends different voltages depending on the exterior temps. If this is malfunctioning then your HVAC cannot tell the difference between cabin temps and exterior temps to properly adjust the internal temps. If you are handy you can measure the resistance between the two leads (32 Deg F should = 6K Ohms, Higher temps equals less resistance).

For Remaining Interior Tests with the HVAC and no Consult Tool follow this PDF for detailed instructions on how to troubleshoot your HVAC system. https://drive.google.com/file/d/0BxXnGX ... sp=sharing