AC making car slow down..

[Hectorb25]

Just got the AC repaired in my gst and whenever i have it on it slows down the car by alot , sometimes even making it have problems in first gear, what can this be? anyone?

 

[g4ebguy90]

Is your car a automatic or manual?

Whats the idle like?

The A/C should really not have a noticeable load on the car, a higher idle is really all you should notice. It is possible that something is drawing way to much current whenever the A/C is engaged. This would put more stress on the entire cars charging system.

Low battery voltage can cause problems with a automatic trans car. As most of its solenoids are ran by electricity and not hydraulic these days.

 

[DSM1G90]

Guess again: A/C does make a drastic effect with 4cylinder motors since they rob a good 15hp off the end of the crank for the compressor..and for a low torque producing motor like any 4cyl motor, that's quite a bit.

That is why 1st gear is being tough on you - most of the motor's low torque at a the low RPM is to spin the compressor. Our motor's don't peak torque until almost 5600RPM's..and I'm sure you don't want to start out in 1st at that high of RPM's.

Guess you're gonna have to learn how to get out of 1st all over again since you got the AC fixed.

Why AC and 4cyl motors don't mix too well.

I bet you'll be taking the belt off, or keep the AC off when you shift out of 1st ..

-DSM

 

[Anubis_4_99]

it's normal, same thing happens with mine, kind of irritating but I'll deal with it for the trade off of having working a/c.

 

[Hectorb25]

i just thought something was wrong with the car itself , i dont mind the slowness im not into the racing things but i just wanted to make sure it was normal in some occasions.

 

[g4ebguy90]

Yea if A/C slows your car down to where it irritates you. Something is not right. As for the compressor using 15hp... I can't believe that at all.

 

[brian102]

Same thing on mine. You can tell for sure when ac is on.

 

[Boostinsideways]

Yea if A/C slows your car down to where it irritates you. Something is not right. As for the compressor using 15hp... I can't believe that at all.

Dude the superchargers on some cars can use as much as 200 horsepower to spin up to full boost. Granted these are usually positive displacement s/c on high output v-8s.

The AC when its on full blast should be taking about 10-15 hp. And our engine isn't very torquey at low revs.

Just give a little more gas on accel. Take off about 1800 rpms instead of 1200. It takes a bit of getting used too. The ac on my 1g was murdering 1st gear low rev take offs.

 

[g4ebguy90]

Dude the superchargers on some cars can use as much as 200 horsepower to spin up to full boost. Granted these are usually positive displacement s/c on high output v-8s.

The AC when its on full blast should be taking about 10-15 hp. And our engine isn't very torquey at low revs.

Just give a little more gas on accel. Take off about 1800 rpms instead of 1200. It takes a bit of getting used too. The ac on my 1g was murdering 1st gear low rev take offs.

What we on ricetuners? You know how small of a piston is in that compressor. Your telling me that the piston in the compressor is doing as much work as more then 10-15% of are engine. Remember are turbo engines are like 7.8:1 or 8.5:1 were at like 110-120hp before boost.

Yea superchargers can use 1000hp!...... depending on application. That has nothing to do with a A/C compressor. If you want to guess, which you are.... I would say that it uses roughly 3-5hp. The load that the engine sees is both electrical and mechanical. It does have a clutch, and its already spinning anyways, just not engaged so the piston is not making movement.

 

[DSM1G90]

You know how small of a piston is in that compressor

There are 3 small, 1 inch pistons in that compressor working as a double headed piston set in a triangle form in the chassis - one end pulling freon and the other end pushing freon with an eccentric disc, called a "squash plate" in the middle of these set of pistons that is attached to the pulley on the end.

There is no crankshaft in the unit as a paint compressor's setup.

Why you have to have the compressor oil in them - to keep the pistons lubricated.

And with moving this three piston setup in oil along with the compressed freon..that's gonna be needing a bit of work on the pulley end to move it all.


If you want to see work, the old GM/Fridgiair compresssors in a 4cyl setup would eat up almost 25 hp off the end of the crank since they had much larger pistons inside that casing. Motors had to idle at 1000 RPM's at idle just to run the compressor along with larger radiators and a much larger fan attached to the water pump. When GM went to Hamilton compressors, they got better performance with less HP usage from the motor since they got the compressors downsized to a compact level.

Why V8's were given AC as part of the install and an costly option for 4cyl motor vehicles.

Granted, compressor manufacturing has drastically improved in recent years to allow more fuel effiency esp with the invention of vane compressors to rid of the piston action, but in 1990, these larger compressors were the norm.

-DSM

 

[g4ebguy90]

I have to take mine apart. I didn't know it was a airplane engine.

 

[bryanwheat]

Every turbo dsm i've ever had with ac definitely felt like a turd with the ac on. Especially in the low rpm's out of boost. This is perfectly normal.

 

[DSM1G90]

they make them like this just to save space, weight and to get the same output as the larger ones.

Early FORDS actually used large, two piston, crankshaft compressors for their large big stroke and bore V8 setups and had to use two belts to turn that compressor pulley, but when that compressor kicked in, it didn't phase that big block motor at all.

 

[4G63madness]

My 2 cents ride with the windows down and save gas, but in south florida AC is crucial!

 

[Doubleot]

Yep, perfectly normal. It is very noticeable.

Hell in my DD 95 Integra, Which is already gutless, with the A/C on it seems nearly impossible to make it to 60MPH unless I'm in 4th gear at 3500Rpm

 

[badbluething]

AC should only take away 5-10HP MAX