Question about A/C usage after starting engine on a really hot day

[cawimmer430]

I'm down in M?hldorf for the weekend and I have no garage for the BMW so it tends to be parked on public parking lots. It's a really hot day today. Really hot. The car was parked outside for nearly half the day. Upon entering the car I immediately turned on the A/C to maximum coolness and full power and then drove away.

Here's my question.

Is this in any way harmful to the engine or A/C components - using the A/C at full power immediately after starting the car as it was parked in the blazing heat for several hours?

[MX793]

Short answer:  No.

[cawimmer430]

Short answer:  No.

Good to hear. Because I'll be using my A/C like this very often in the upcoming days in this terrible heat.

[shp4man]

An air conditioner works by moving heat from the inside of the car to the heat exchanger in front of the radiator. The more heat it moves, the more power it takes to run. Hopefully, BMW overbuilds the cooling system and charging system enough to take the load.

[MX793]

An air conditioner works by moving heat from the inside of the car to the heat exchanger in front of the radiator. The more heat it moves, the more power it takes to run. Hopefully, BMW overbuilds the cooling system and charging system enough to take the load.

Seeing as the interior of a car that has been sitting out in the sun on a hot day is generally warmer than the ambient outside air, the A/C actually has a easier time pumping heat out of the car.  At least initially.  It's when you start trying to cool the car to temperatures below the outside ambient that it really needs to work to move heat.

[Raza]

Yes.  If you use the air conditioner, it will explode. 

[cawimmer430]

Damn, what did you guys study in college? Rocket science?  

Thanks for the responses. Abused my A/C again today after starting up the car. God damn what a hot day. It's so hot here I want to walk around nude!  

Yes.  If you use the air conditioner, it will explode.  

[MX793]

Damn, what did you guys study in college? Rocket science? 

As a matter of fact, I actually did study rocket science in college.

[Eye of the Tiger]

I actually studied air conditioning in college, but I'd go with whatever the rocket scientist says.

[2o6]

OK, somewhat related:


My mom says that using the heater burns up gas.


I think she is wrong, since hot coolant is going through the heater core already, and the blower is nothing more than an electric motor that moves the air from the heater core to the cabin.



Am I wrong?

[Eye of the Tiger]

OK, somewhat related:


My mom says that using the heater burns up gas.


I think she is wrong, since hot coolant is going through the heater core already, and the blower is nothing more than an electric motor that moves the air from the heater core to the cabin.



Am I wrong?

The heater makes no difference. Either all the heat goes out the radiator, or some of it is diverted to the heater.Just a small amount of energy is used for the blower motor.

[Laconian]

Your mom seems to be very opinionated about her theories of how cars work.

[cawimmer430]

As a matter of fact, I actually did study rocket science in college.

RESPECT! 

I remember you mentioning a few years ago something about mechanical studies in college or something along those lines.

[cawimmer430]

I actually studied air conditioning in college

[Rupert]

OK, somewhat related:


My mom says that using the heater burns up gas.


I think she is wrong, since hot coolant is going through the heater core already, and the blower is nothing more than an electric motor that moves the air from the heater core to the cabin.



Am I wrong?

She's way off. The AC can use more gas, but that's mostly in older cars.

[ifcar]

OK, somewhat related:


My mom says that using the heater burns up gas.


I think she is wrong, since hot coolant is going through the heater core already, and the blower is nothing more than an electric motor that moves the air from the heater core to the cabin.



Am I wrong?

You're only wrong if she drives a Chevy Volt.

[S204STi]

Yes.  If you use the air conditioner, it will explode. 

+1.  I don't care what variety of rocket surgery these guys studied, I once saw an engine asplode with the AC on, so obviously that was the cause.

[2o6]

Your mom seems to be very opinionated about her theories of how cars work.

She told me her Econoline has cylinder deactivation.

[ifcar]

She told me her Econoline has cylinder deactivation.

It's probably called "misfiring."

[Rupert]

Dead (not firing) cylinders don't count as cylinder deactivation...

[Laconian]

The Chevrolet Corvair used gas for the heater:

"The passenger compartment was heated by a gasoline heater mounted next to the spare tire in the luggage compartment. While it offered immediate hot air, customers complained of what they thought might be decreased gas mileage on cold days and through long winters. Chevrolet redesigned the heating system for the 1961 model year, yet left it up to customers to choose the gas heater until the end of the 1964 model year."

I saw a Corvair convertible just yesterday. It's cool that GM let its engineers go nuts on that car, but it wasn't smart to give them a mainstream car as their playground. At least with the Porsche 911, all the handling weirdness would be dismissed as "it's an exotic, gotta treat it right!"

[S204STi]

Sweet zombie Jesus, I'm surprised more people didn't DIAF back then.

[hounddog]

The heater makes no difference. Either all the heat goes out the radiator, or some of it is diverted to the heater.Just a small amount of energy is used for the blower motor.

My understanding is that the defroster runs off the AC pump.

If true, then she could be at least partly right, right?

[Eye of the Tiger]

My understanding is that the defroster runs off the AC pump.

If true, then she could be at least partly right, right?

Most cars do run the AC when the defroster is selected. I like to bypass that feature to save gas.

[Byteme]

I'm down in M?hldorf for the weekend and I have no garage for the BMW so it tends to be parked on public parking lots. It's a really hot day today. Really hot. The car was parked outside for nearly half the day. Upon entering the car I immediately turned on the A/C to maximum coolness and full power and then drove away.

Here's my question.

Is this in any way harmful to the engine or A/C components - using the A/C at full power immediately after starting the car as it was parked in the blazing heat for several hours?

Modern car AC systems could almost cool a small house. 

Turn the air off, start the car, roll down the windows for a minute or so to expell the trapped hot air while you:  turn the air to MAX AC or Recirc (depends on how your's is labeled) and turn the blower to max and the temp as low as it will go.  After a minute or so roll the windows back up.

[hotrodalex]

I try not to use the A/C in my Saturn, I just roll the windows down. A/C sucks too much power and kills any hope of acceleration.

[MX793]

Modern car AC systems could almost cool a small house.  

Turn the air off, start the car, roll down the windows for a minute or so to expell the trapped hot air while you:  turn the air to MAX AC or Recirc (depends on how your's is labeled) and turn the blower to max and the temp as low as it will go.  After a minute or so roll the windows back up.

Seems to me that newer car ACs don't cool nearly as well as they did 20 years ago.  The AC in my old 240SX was far better at cooling the cabin than my Mazda has ever been (and I suspect the 240 might have even been due for a system recharge).  Haven't driven the Mustang in hot weather yet to see how that one does.

[shp4man]

R134a is a little less efficient than R12 at cooling, but doesn't affect the ozone layer.

[hotrodalex]

Our Mazda6's AC isn't very good; it's about as cool as my Saturn's fan without the AC on. I'm thinking it could just be a Mazda thing.

[Byteme]

Our Mazda6's AC isn't very good; it's about as cool as my Saturn's fan without the AC on. I'm thinking it could just be a Mazda thing.

Our 3's and 6's AC cool the interior well enough so that I could hang sides of beef in the back seat.  My wife and son like it cold, I don't. So I usually shut the pneumonia holes blowing cold air at me or redirect them at them. 

The Miata's AC is marginal.