How much HP does the A / C actually draw?
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Same issue here. Cavalier does NOT like A/C running one bit. No difference with the Mustang or Expedition though.
The difference is probably torque. The 265hp engine is not using all its torque down low while the 105 has little torque down low on the power curve.
There was a dyno plot done years ago and was in a Honda tuning book (I remember leafing through it at Barnes & Noble), and I want to say it showed a 10-15% loss with the A/C running and all other lights/electrical....so "fully loaded". In a 100hp engine, that's pretty significant.
An original a/ c unit on a 67 Mustang pulls approx. 5 H,P. John--Las Vegas.
It robs a lot of power... The good news is that with the new CAN system in the ECM's of late it setup to have the transmission, ECM and other systems all talk to each other for optimal fuel economy, performance and may delay the compressor from kicking in until it's the best time such as the engine is at optimal rev's or you aren't passing ms. daisy who's out on a Sunday drive on the highway.
Some vehicles like my Santa Fe don't have this advanced network so we have to push the A/C button to turn off the compressor or stop it from kicking in when we need all the power we can get.
Some vehicles like my Santa Fe don't have this advanced network so we have to push the A/C button to turn off the compressor or stop it from kicking in when we need all the power we can get.
I have read they draw 25HP
Originally Posted By: Bluestream
I have read they draw 25HP
Yes, I had read the same thing sometime back. One of the inherent problems is the use of 134a instead of R12. The 134a is less efficient and robs more HP..Witness the higher head pressures involved. Fortunately I have a rather large stash of R12 and use it in 3 vehicles. Best regards. John--:as Vegas.
I have read they draw 25HP
Yes, I had read the same thing sometime back. One of the inherent problems is the use of 134a instead of R12. The 134a is less efficient and robs more HP..Witness the higher head pressures involved. Fortunately I have a rather large stash of R12 and use it in 3 vehicles. Best regards. John--:as Vegas.
Originally Posted By: Torino
An original a/ c unit on a 67 Mustang pulls approx. 5 H,P. John--Las Vegas.
I read of a study an automaker did comparing using the A/C to running without A/C and the windows down. I know they concluded the two methods were equivalent, I think they figured the HP loss at 5-6.
An original a/ c unit on a 67 Mustang pulls approx. 5 H,P. John--Las Vegas.
I read of a study an automaker did comparing using the A/C to running without A/C and the windows down. I know they concluded the two methods were equivalent, I think they figured the HP loss at 5-6.
Originally Posted By: StevieC
Some vehicles like my Santa Fe don't have this advanced network so we have to push the A/C button to turn off the compressor or stop it from kicking in when we need all the power we can get.
My 22-year-old Mustang GT has this feature that cuts off the AC compressor at wide-open-throttle.
Pretty state of the art...for 1988.
Some vehicles like my Santa Fe don't have this advanced network so we have to push the A/C button to turn off the compressor or stop it from kicking in when we need all the power we can get.
My 22-year-old Mustang GT has this feature that cuts off the AC compressor at wide-open-throttle.
Pretty state of the art...for 1988.
I don't think the amount of HP needed to run a compressor is anywhere near 25HP.
For one thing, that's the equivalent of about 18,640 watts..and car AC systems have around 3 tons of cooling capacity from what I've read.
If you have a Scangauge, see how much the engine load goes up when you turn on the AC.
For one thing, that's the equivalent of about 18,640 watts..and car AC systems have around 3 tons of cooling capacity from what I've read.
If you have a Scangauge, see how much the engine load goes up when you turn on the AC.
Originally Posted By: brianl703
I don't think the amount of HP needed to run a compressor is anywhere near 25HP.
I was thinking the same thing. Some vehicles these days utilize an electric motor to run the compressor - a 25 hp electric motor would be huge!
I don't think the amount of HP needed to run a compressor is anywhere near 25HP.
I was thinking the same thing. Some vehicles these days utilize an electric motor to run the compressor - a 25 hp electric motor would be huge!
A 3 ton home a/c unit will run on a 50A 220V circuit running two fans and the compressor, that's 11,000 watts or roughly 13 hp.
With the AC on you may dyno 60 hp at the wheel. What do you do?
Originally Posted By: tom slick
A 3 ton home a/c unit will run on a 50A 220V circuit running two fans and the compressor, that's 11,000 watts or roughly 13 hp.
My 2 ton unit is on a 25A 220V circuit and the actual measured current draw is 8.2A @ 220V with an outdoor temp of 78F.
A 3 ton home a/c unit will run on a 50A 220V circuit running two fans and the compressor, that's 11,000 watts or roughly 13 hp.
My 2 ton unit is on a 25A 220V circuit and the actual measured current draw is 8.2A @ 220V with an outdoor temp of 78F.
I don't know how much power it draws, but it is a LOT. Seriously, anyone who's ever driven a small 4cyl car (especially one that is underpowered to begin with, ie a cavalier) knows that Turning on the A/C makes it dangerously slow. I have to turn it off to merge onto the highway or it just takes way too long to get anywhere. I actually am thinking maybe it isn't the horsepower it takes, rather it's the resistance to change speed.
I've only heard of somthing in the 5-6HP range before IIRC.
Im sure it varies though as somthing like a newer scroll, rotary vane or small variable displacement recip. compressors sap much less power than say A big 'ol industrial-sized York or A6 compressor.
Im sure it varies though as somthing like a newer scroll, rotary vane or small variable displacement recip. compressors sap much less power than say A big 'ol industrial-sized York or A6 compressor.
It would would be hard to say how many HP w/o knowing actual BTU/h for a given car. Size of the compressor varies.
But ball park numbers are:
1 ton cooling power =12k btu/h
If it is a two tone unit then it draws 24k btu/h of energy.
1 ton=12k btu/h
1 hp=2,544 btu/hr
therefore for a 2 ton unit it draws 12k/2544=9.4 HP
3 ton unit 36k/2544=14 HP
There are also mechanical losses as well such as noise, heat& belt on top of that.
I did not include the power drawn by the fan either.
But ball park numbers are:
1 ton cooling power =12k btu/h
If it is a two tone unit then it draws 24k btu/h of energy.
1 ton=12k btu/h
1 hp=2,544 btu/hr
therefore for a 2 ton unit it draws 12k/2544=9.4 HP
3 ton unit 36k/2544=14 HP
There are also mechanical losses as well such as noise, heat& belt on top of that.
I did not include the power drawn by the fan either.
Originally Posted By: brianl703
Originally Posted By: tom slick
A 3 ton home a/c unit will run on a 50A 220V circuit running two fans and the compressor, that's 11,000 watts or roughly 13 hp.
My 2 ton unit is on a 25A 220V circuit and the actual measured current draw is 8.2A @ 220V with an outdoor temp of 78F.
That's what I was getting at, there is no way a automotive a/c unit uses 25 hp.
Originally Posted By: tom slick
A 3 ton home a/c unit will run on a 50A 220V circuit running two fans and the compressor, that's 11,000 watts or roughly 13 hp.
My 2 ton unit is on a 25A 220V circuit and the actual measured current draw is 8.2A @ 220V with an outdoor temp of 78F.
That's what I was getting at, there is no way a automotive a/c unit uses 25 hp.
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