Coolant temp influence on AC output

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Originally Posted By: Cujet
Originally Posted By: supton

Mechanical or electrical fan? I bet i either case it just isn't turning, as the engine temp hasn't risen enough to do so.


The Ecoboost has an electric fan. It runs anytime the AC is on, which is about all the time around here.


Any chance a pusher fan could be added in front of condenser??
 
Originally Posted By: JimPghPA
You have 1772 post here on BITOG and you do not understand how heat is removed from the air conditioners condenser and the engines radiator.

One does not have anything to do with the other, though if the engines cooling system is not good the heat from the AC condenser warms the air before it goes through the engines radiator, and could cause the engine to run a couple of degree hotter.

Both are affected by the amount of air moving through them, and when the vehicle is moving there is more air moving through them, compared to when the vehicle is stopped and the only air that is moving through them is air pulled through them by the vehicles fan.

When stopped the coolant temperature climbs because there is less air moving through the radiator (the black thing that transfers heat from the engine coolant to air). When the vehicle is moving air hits the front of the vehicle and causes more air to pass through the radiator.

When stopped the air conditioner blows warmer air because because there is less air moving through the condenser (the air conditioners silver colored radiator looking thing in front of the engines radiator). When the vehicle is moving air hits the front of the vehicle and causes more air to pass through the air conditioners condenser. When more air moves through the condenser it can dump more heat into that air, and the gas refrigerant entering the condenser can change to a liquid easier, and the liquid refrigerant leaving the condenser is cooler. When the cooler refrigerant changes from liquid to gas inside of the evaporator it produces a colder temperature and the evaporator removes more heat from the air passing through it, making the air blowing into the passenger compartment colder.

Also when the engines RPM's are higher than idle the water pump and AC compressor are both turning at higher RPM's compared to being at an idle.


My silver thing is black,,and my black thing is silver. Is my car going to be ok?
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Originally Posted By: Cujet
Here in hot-n-sticky South Florida, my 2011, Ford F150 3.5L Ecoboost has awful air conditioning when stopped, such as when first starting up. In fact, it never gets really cool until I've driven for a while.

As you would expect, it's performance is not great in a typical Miami traffic jam.

Once going though, cooling is excellent. Charge level is perfect, and revving the engine up does nothing to help. I think it's simply a matter of airflow over the condenser.



There, I am surprised, because your truck has a set of the most ludicrously overpowered cooling fans I've seen. They've legitamitely and independently been tested to pull over 6500 cfm at full tilt. I'd look for a problem.
 
Originally Posted By: mjoekingz28
Wondering why, when stopped, the coolant temp climbs and the air vents blow warm. Car moves, temp lowers, and vents are cold again.


What does one have to do with the other?


If you have an LT1, check that your fans are going into high speed with the AC on. If they are not, remove the high speed relay and see if they kick into high. If they do, replace the relay.

Your fans should kick into high when AC high side pressure hits 240 psi, or when engine temps hit 232° (yeah, I know, thanks GM). Otherwise, they're going to sit at low speed, the default setting with AC on.

Sounds like you're stuck in low speed to me. My LT1 Roadmaster did the same thing because of a blown seconday relay. We have the same programming for fan operation,,but we have a second fan that comes on to accompany the first,,while you guys have both fans running at high or low speed.
 
Originally Posted By: Cujet
Originally Posted By: supton

Mechanical or electrical fan? I bet i either case it just isn't turning, as the engine temp hasn't risen enough to do so.


The Ecoboost has an electric fan. It runs anytime the AC is on, which is about all the time around here.

It does a great job of keeping the engine cool. It does not do a great job of pulling enough air through the condenser.

My 2009 F150 5.4L V8 has a huge, high blade pitch, mechanical fan with electric clutch. It's a cool setup and very effective. At idle, with AC on, the clutch engages and there is a roar of air under the hood and the AC is ice cold at idle or in traffic jams.

Same basic truck, very different methods of moving air through the radiator and condenser.


My Navigator has the same mechanical fan. I've heard it go straight Mack truck loud one time when the radiator drain cook got loose and let some coolant out. AC can get meat locker cold in the worst heat.
 
Originally Posted By: DoubleWasp
My silver thing is black,,and my black thing is silver.


See a doctor
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Thanks gentlemen. Apparently a thermostat can fail partial...re: not stuck open or closed.

The 2006 or so Toyota Sienna van would be fine moving, but while stopped the coolant temp would rise and the AC air would be warm. I checked for fan operation and it/they were turning. Owner said it needed a thermostat.
 
Originally Posted By: DoubleWasp
Originally Posted By: Cujet
Here in hot-n-sticky South Florida, my 2011, Ford F150 3.5L Ecoboost has awful air conditioning when stopped, such as when first starting up. In fact, it never gets really cool until I've driven for a while.

As you would expect, it's performance is not great in a typical Miami traffic jam.

Once going though, cooling is excellent. Charge level is perfect, and revving the engine up does nothing to help. I think it's simply a matter of airflow over the condenser.



There, I am surprised, because your truck has a set of the most ludicrously overpowered cooling fans I've seen. They've legitamitely and independently been tested to pull over 6500 cfm at full tilt. I'd look for a problem.


Likewise. Our SRT has electric fans and they never let the AC get warm no matter what. Some of the best AC ever in my driveway even at triple digit temps in Fl. Indicated 102F just the other day.

The new Ram has both a mechanical fan and an electric one right on the AC condenser. Seems to work equally well.

In our service vans with real centrifugally clutched fans (not thermostatic) the AC getting warm at stoplights tells you the fan clutch is getting weak from sustained stationary operation...
 
Does your car have an intercooler in front of the condenser? After a while, those heat up, and then reduce the amount of cool air flowing over the condenser.

I sometimes notice it in my car.
 
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