Over heating when I turn my A/C on

[Miss Q45]

I really need help every time i turn my A/C on my car over heats not right away i say about 20 minutes or so. I really need my A/C I live in Arizona and today it was about 113 degrees and i had to drive 2hours today without air after I had to stop and let my car cool off. As long as i keep the air off i don't over heat. Please Help.

[Razi]

How's your coolant level?Do you know if your fan is working correctly?

[Miss Q45]

not sure if my fan is working coolant is okay

[Miss Q45]

My air blow cold i just over heat when its on and of course my coolant runs out I filled it up once the car cooled down I drove the 2 hours home with out air and no over heating. I drove about 20 minutes with air just to see what will happen and sure enough It starts to overheat again.

[maxnix]

So tell us about your cooling sysem maintenance, condition and mileage on the car.

[Miss Q45]

I had the car for about 1yr. never had any maintenance on the cooling system. I have about 130 miles on it now. I try to keep up with the regular maintenance on the car. I just had the alternator replace 2days ago. About 8 months ago I had a new radiator, thermostat, new gas line and 4 injectors done. No tune up yet every time I ask some one about that they say i dont need one

[maxnix]

Be sure to include the MY of your car in your porfile.

How about the viscous fan clutch? Does it spin freely when the engine is off?
Modified by maxnix at 9:32 AM 6/30/2008

[Miss Q45]

I DONT KNOW WHAT THE VISCOUS FAN CLUTCH IS BUT I DONT HEAR ANY THING RUNNING ONCE I TURN MY CAR OFF

[maxnix]

OK, we can read pretty well, so NO NEED TO SHOUT!

Why don't you start by downloading an FSM a reading through the coling section? Your main fan has a viscous clutch and if it failed, it will not engage when required, thus the additional thermal load from your consenser may be pushing your cooking system over the top.

Over heating is very fatal to aluminum components on any engine, of which the VH45DE is almost entirely made.

http://www.nicoclub.com/FSM/Q45/

[Q45tech]

If the Q doesn't overheat without AC obviously the normal common failure points maybe ok or only slightly reduced in efficiency.

At extreme outside temps the AC ADDS 30-45 degrees [in traffic slow speed] to the input air the radiator sees.

Check auxillary electric condenser fan and the sensors that turn it on and change speed.................it has a fuse behind battery that may have blown from worn out fan motor.

You must be more specific as when the overheat occurs in city traffic or 60 mph on highway.

Time in minutes and seconds of temperature climb is important and needs to be measured and graphed using consult to see REAL COOLANT temperature ecu sees.

Try 25% AF vs 50% AF to prolong the time to overheat since water is a better heat transfer agent.

Was the replaced radiator OEM or aftermarket, there seems to be a 5% difference in some low cost brands...........not as important in cooler places but can throw you off the cliff in 115F vs 95-100F locations.

Give use additional info and we can narrow it down.

[Skibane]

The "Viscous Fan Clutch" is a circular, finned aluminum "pancake" that is mounted to the back of the main plastic radiator fan, connecting this plastic fan to the fan belt pulley on the engine. When it's working properly, a built-in thermostat forces it to make a strong mechanical connection between the fan and the pulley whenever the air flowing through the radiator gets hot enough. This solid connection allows the pulley to spin the fan at full engine speed, thereby providing maximum cooling.

During cooler weather, this fan clutch loosens the mechanical connection, allowing the plastic fan to "freewheel" at a much slower speed.

The fan clutch tends to wear out over time, resulting in the plastic fan never spinning at full engine speed. This reduces the fan's ability to cool the engine, particularly during slow-speed driving (when little air is forced through the radiator due to vehicle speed alone).

When the fan clutch is working properly, the engine will make a louder roaring noise in hot weather, due to the fan always spinning at full engine speed. Another test is to shut a warmed-up engine off during hot weather and immediately attempt to spin the fan with your hand - If the fan clutch is doing its job, it will be difficult to spin the fan, which will immediately come to a complete stop. If the fan spins easily and doesn't stop rotating immediately, it means that your fan clutch is no longer making a solid mechanical connection between the fan and the fan belt pulley, and needs to be replaced.

[BadQ45t]

You just had it at the radiator shop in Phoenix, god knows those guys should be covering this under their warranty. I had issues with my car when I survived my 3 summers in PHX. Take it back there and demand they figure it out. You bought all the parts and labor from them only 8 months ago, they give at least 1 year warranty. Tell them what is happening, more than likely given you have a new radiator (or did they core your old one which is just about as good as a new one) so the fan might be it. I had issues too with my car running hot only with A/C on but a new thermostat and radiator core (heavy duty cleaning) and I was back in business. I was in PHX in 1990 when we broke the all-time heat record, 122 at Sky Harbor!! That day was when the car wouldn't run with A/C, I nearly died driving home. Got it cored and the next day 119 and ice cold air no issues.

[xmateo]

I'm buying a fan clutch tomorrow. Any tricks to intalling? Is it better /or easier to replace the plastic fan at the same time?

[xerexabante]

Check the Auxillary Fan for the A/c system.

[elwesso]

the thing that concerns me is if you have to add coolant. you should never have to add anything. Maybe you have a leak somewhere, probably under the plenum..

When you say overheat, how hot does it get? Does the needle get to the top line, or does it just start to raise? Both are concerns, but its good to know...

With the car off, open the hood. The fan is right in the front of the the motor. Take your finger and give it a good spin.. Dont worry, its not price is right rules, if it doesnt make it all the way around it still counts... .. anyway, give it a good spin, you shoudl feel some resistance and it shouldnt turn more than 2-3 blades before it stops..

the aux fan is something to check too... when the engine is "overheating", open up the hood... On the passenger side near the headlight youll see a black plastic fan. See if its on, if its not that could be a contributing factor (however I dont think its the problem in itself)

[maxnix]

There are two auxiliary fans on the FGY33.

Why do I see this car on the side of the road somewhere in AZ?

[Q45tech]

What is worse is there is nothing unique about the cooling, heating, or ac system in an Infiniti, Nissan, GM, or Ford. Within narrow bounds, nothing has changed for 50 years...............sure some efficiency tweeks and electric fans and fancy controls, but mechanically the same.

The typical current owner IS LESS COGNISCENT of what's going on in a vehicle than they were 30 years ago.

Every car I driven since the 55 Coup Dville [1963] has had AC and the coolant got warmer with AC on and overheated unless maintained and kept CLEAN.

[xmateo]

Why do I see this car on the side of the road somewhere in AZ?

My car is not overheating (different guy). A loud whinning / hiss noise comes from the engine. I believe its the fan clutch since is spins freely, and has too much play in it - I can get it to wobble when it should not. Not sure if I should replace plastic fan at same time.

Not sure if I will need to disconnect some A/C lines to get to everything. Looks like I will be able to work on without removing the radiator - I hope.

[maxnix]

My car is not overheating (different guy).

I was thinking of him. But do get your repaired soon. Greg knows of European Motors (?) in Phoenix who do good work.

[gammer_ghn]

As you said that you pull over to the side and wait for it to cool off is bad! as you drive you should turn you heater on to 85 and watch the heat gauge go down on your car... than you can pull off to the side to get it checked! You can do major damage if you just pull off to the side without colling the car first!!!

[maxnix]

Absolutely correct unless the engine is already damaged. Heat soak for brakes is not good either, like stopping right after you come down off a mountain pass.