It's twice now while driving on the highway I noticed my temp gauge rise above the half mark. I kicked in max heat to drop temp back to below half. While on small streets, the temp gauge is okay. I've replaced the thermostat last week because it happened a few days prior to replacement. Today I idled the motor for 15min to get any bubbles out and noticed the heat was not hot. Gave it gas and heat kicked in and stayed hot. Also noticed the fan did not kick on. Played with the fan controls and noticed that only in defrost that the fan will kick in. All other settings such as feet, face/feet, face, defrost/feet will not trigger the fan. Is this normal or do I have a problem? Thanks.

 

You probably need a new heater control switch. I say that because if it only works in the one position to me that indicates a bad switch.

 

When you say defrost what you mean is the radiator fans only run when the AC compressor is on. Defrost mode automatically engages the AC compressor.

You should replace the temp sensor for the ECU. There are 2 temp senors. The other one is for the temp gage in the cluster.

DW

 

Thanks. I will look at the Manual and get this temp sensor replaced. I'll start with the Coolant temp sensor for the ECU. Thanks for all the help. Will post results to see what I find.

 

I have the manual controls. And as what DW said, switching to Defrost will engage the AC and kick the fan on. It may be a bad switch or temp sensor. Heat blows from all controls when each is activated. Just trying to figure out why the fan does not kick on even after 15mins of warm-up.

 

ects is prolly your problem last summer i had a issue of the gauge going over half way and the sensor was new replace with another one and problem stopped try that

 

I too have a question "fan question." I just recently replaced the alternator in my 95, and to do that I removed the radiator along with the fan attached to it. I never really looked at the fans before, but are they supposed to run all the time when the car runs, or just intermittently when the car needs em?

I just started the car after putting everything back together and have not seen the fans run yet. Got a little worried, so I shut it down and came to ask the pros here.

 

The radiator fans only operate when the coolant gets above 200f or when the AC compressor is operating. As stated earlier the AC compressor operates when either the AC or defroster is turned on.

To check if the fans are working turn on your AC or defroster.

 

Don't just replace the ect measure it with a simple ohm meter to see if that's indeed your problem. Easy to do any might save you the expense and work to replace a part that isn't causing your issue. Search on here for a table of the resistance values.

That would be working smart, not blindly.

 

Drak, the fan will run when the engine reaches a certain temp, so it's ok that the came did come on when you just started up. It's also winter so the engine will run cooler

 

Meant to say it's ok that the fan didn't come on when you just started up. Mine doesn't either

 

why'd you remove the radiator to replace the alternator? definitely an unnecessary step.

 

I don't think that you have all the air out of the engine. Have the front end of the car elevated, either parked on an uphill incline or car ramps and and idle it with the radiator cap off.

 

Oh cool, thanks guys! So far the engine temp in my car hasn't gone too high or anything, so far it all seems good.

WesCTR: Maybe, but this was my first time delving into it. I had to unscrew the compressor and lower it, and thought it would just give me more room to work and get my hands in there. The space is kinda cramp down there as you know.

Also had a little confusion with the spacer that comes on the alternator in one of the mounting ears, but that should probably saved for a different thread (although I don't have permissions to start a new thread yet).

 

Last couple days the engine temp climbs fast from startup to operating level which is below the middle. When gas applied, heat gets hot. When idle, heat goes warm or cool/cold. Should I replace Autozone tstat with OEM tstat? Waterpump?

 

OEM thermostat. I bet the OEM tstat looks way beefier than the autozone one you have.

No way its the water pump. The water pump only fails by leaking.

DW

 

still have air in the system

 

I still think air in the system is your problem. My second guess is that the impeller blades on the water pump have corroded off. The thermostat comes in at guess # 10 or 11.

 

Whoah. Does that like even happen on Maximas?

The water pump unit is a pretty tough all steel/aluminum unit. It's chain driven so it's got hot motor oil running on one side of it with hot anti-freeze on the other. The fluids never mix until the water pump gasket starts to slowly fail.

DW

 

Yes it does. Someone posted side by side pics of his old, original water pump and the new one. I don't remember who it was. It was an answer to someone with a overheating problem.

 

That must be rare and may be due to extreme neglect with anti freeze on someones maxima.

I mean sheesh. That's bad.

DW