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Turning on AC on high at startup or on high when starting, will this damage the car?

My wife scolds me for leaving the AC on high when she needs to ues my car, so when she starts the car (a 1999 VW Jetta Standard Transmission)she feels like it is hard on the car to leave it on high. We also own another car (a 1999 VW Passat standard Transmission) that I may ocassionally use that she drives. What is the real impact on a car when this happens?

read this…

also google “AC on when starting car” for more information

No. There is no impact.

“High” only refers to the fan speed, it makes no real difference, certainly won’t damage anything.

It absolutely will shorten the life of the starter.

Does that mean it ‘damages’ the starter? Not technically but it does make the car harder to start if the compressor is engaged too.

Doubt that, most compressors disengage during starting. And how, exactly, do you know that? Have you compared relative starter life with and without AC?

You are absolutely, wrong. The OP’s car turns the AC off while the car is starting and until the engine reaches idle speed. The position of the AC switch or fan switch makes no difference at all. Why is there so much confusion about this?

tardis is correct. Don’t worry about it.

In every car I’ve encountered the ignition switch cuts power to all accessories when the key is held in the “start” position.

It has no effect.

When starting the engine, the AC compressor isn’t rotating fast enough to develope enough pressure in the AC system to close the contacts at the low pressure switch for the compressor. Until that happens, the compressor won’t operate.


At startup the compresor should not be turning at all.

YOu leave the blower in the noisy high position? Do you leave the radio on loud too? That would drive me bonkers and may drive your wife crazy too. How am I supposed to start the car if I can’t hear the engine?

Think about what you are saying.
The low pressure switch determines if the compressor is allowed to run at all. If the compressor had to turn to allow this switch to come on, the compressor would never be allowed on. It’s a chicken vs egg argument. The low side pressure is high enough to allow the compressor to run anytime it is not running (if the system is correctly charged). It’s when the compressor is running, that the switch may kick out and turn the compressor off until the pressure recovers. Perhaps you should get a book on how car AC systems work.

All of this has nothing at all to do with the OP’s question. The compressor is off during engine start because electrical power to the whole clutch circuit is interrupted by the ignition switch being in the start position. In addition to that, the engine computer will keep the AC clutch off until the engine has reached or exceeded proper idle RPM.

The heater/A/C fan and the radio and all other accessories ore OFF while starting an engine. You should be able to hear the engine start.

Oh, so YOU’RE the practical joker who leaves the ; wipers on, the fan on high, the seat all the way back and reclined, the hood & doors un-latched, the turn signal on, the mirrors all askew, etc. :wink:

But really, although there’s no mechanical problem from leaving the fan on high…why would you ??
Especially since your wife has voiced this as being an issue with her. Your action, or lack thereof, speaks volumes as to your personality.
Why do you not care about her opinion here ? What else in your lives do you ignore her requests and make no effort to adjust or compromise ?

The damage here is to your relationship.

Plan ahead and turn things off or down for the the next use.
( around here you can need the A/C on when you gat off work but tomorrow morning it’s 40. You sure don’t want the a/c on at that time ! )

On this car as most the compressor is not engaged during start period.

Most cars turn off even the radio when cranking the engine. Why would the ac mag clutch be engaged before the engine run position is reached?

Sorry tester my bad.LOL

Well, I don’t bother to turn off all accessories. Usually I need them next time I get in the car. As for the wife, SHE can get over it!!

Running the fan on high will cause the blower to wear out sooner than if you run it on a lower setting, but if you are going to run it on high, you may as well leave it on high. We are talking about [b]your[/b] car, right?

Normally, I would say to do whatever it takes to make her happy, but only if you shared one car or if we were talking about her car. Maybe if she can’t get over this, she shouldn’t drive your car.

Based on this one issue, she sounds kind of like a shrew.