Fluctuating engine temp a/c sends out cold air intermittently

The thermostat "seals" the cool coolant giving up (rejecting) heat in the radiator & heater core from the hot coolant absorbing heat in the running engine "block".

When the coolant in the engine reaches a specific temperature (180 ~ 195 degrees) as determined by the value selected by manufacturer or when replaced, it opens and allows the hot coolant in the engine block to be pumped out to the radiatot & heater core for cooling and the cool coolant in the radiator / heater core is pumped into the engine block - replacing the hot coolant. The thermostat senses cool coolant in the engine block and seals shut until the temperature of the coolant in the engine block rises to 180 ~ 195 degrees again. This process continues over and over for as long as needed.

You should check to make sure that the coolant level in the reservoir / radiator is sufficient by checking when cold. Do NOT remove a radiator cap when it is hot! With the cap off, start the engine and add additional coolant as the engine warms up to normal operating temperature. If coolant levels are ok, the trouble could be related to the thermostat or possibly a faulty temperature sending switch. This means that the temperature of the coolant is fine - but the switch or sensor that converts the temperature to a voltage for the gauge on yur dashboard is the problem.

If the temperature is fluctuating up and down, you should have it fixed. Good luck!

My 2008 had the same problem. It turns out that the coolant system, if not filled properly will cause air to block the transfer heat in the heater core. This is what I did, and it worked, while your motor is cold, pop open the caps on your radiator and your overflow. Top off your radiator to the brim with antifreeze, put caps back on. Start and bring up to operating temp, (I just drove to the grocery store). This will work any vapor bubbles trapped to get flushed out, and then repeat. This can take 2 or 3 times. Easy fix.

Maybe your radiator is clogged.

you could have an air lock would bleed heater hoses

For car running hot and overheating issues, I suggest to you go through this help links. Click this link below and go through the troubleshooting procedure to take care of the problems: ----

temp gauge goes erratic? http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html

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Temperature gauge keeps fluctuating up and down close to red? http://technoanswers.blogspot.com/2012/01/temperature-gauge-keeps-fluctuating-up.html

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Car runs hot? http://howtobyme.blogspot.com/2011/11/car-runs-hot-in-traffic.html
-----------All types of car overheating problems and troubleshooting?

http://technoanswers.blogspot.com/2011/11/all-types-of-car-overheating-problems.html
Car freeze overnight and started overheating while driving?http://technoanswers.blogspot.com/2012/01/car-freeze-overnight-and-started.html-----------Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Car overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
--------overheating? http://schematicsdiagram.blogspot.com/2011/12/buick-century-overheating.html
----------Car engine Overheats and transmission starts slipping?http://schematicsdiagram.blogspot.com/2011/12/car-engine-overheats-and-transmission.html
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Temperature gauge does not move and no heat when heater is ON? http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.html

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This details will help.Thanks.

Sounds Like A Problem With your thermostat. Good Luck

First check for low Anti-freeze, then you can squeeze the in-let line prior to the thermostat. It should be hard,when engine is cold. It is good to do this with the radiator cap off since you can watch for water movement while preforming this task, but if it is allowing the water to go through the thermostat; then it is staying wide open. It then will need to be replaced. Your heat should come back at that point.

You may have air trapped in the lines to or from the heater core.
If you (still) have a real radiator cap on the radiator, remove it with a cold engine, start and run the engine allowing it to warm up while watching the water/coolant level. Make sure the heater control is set to its highest heat setting while doing this. If it is trapped air, you may see it 'belch' after the engine is warm and the engine thermostat is open. Refill as needed if this is the case.
It's more difficult without direct radiator access and may require several cycles of hot/cold to allow refilling through the overflow.

you have air trapped in the cooling system. A good indication is that one or both of your heater hoses going into the heater core are cold when they should be hot.
Park facing uphill, raise front of vehicle so radiator cap is higher than top of engine. (You want bubble to get to radiator and out the cap.)
Leave cap on but loose, so bubble can purge.
Turn heater on.
Fill radiator and reservoir with 50/50 mix of antifreeze.
Start engine and run at about 1500 roms until the engine warms up and thermostat opens.
You will know themostat opens when top radiator hose is hot indicating coolant is flowing.
Shut off engine.
Fill radiator and reservoir. Install cap.

please Rate as fixya if this works. good luck

I think you could be right about there being air trapped in the system.
Or the heater core(radiator) is plugged.
Either way you need a pressurized radiator coolant pump to put the coolant in without air being trapped.
Although,i have seen it done by jacking the vehicle up high enough that the radiator was now higher than the heater core level, and then the coolant was put in.
But this is dangerous to try.