Car seems a little slow or sluggish with AC on.

kjkim93

Original poster
Member
Jan 1, 2012
696
I've cleaned the throttle body around 5,000 miles ago. My car ran well. It still runs well. But when i turn the AC on the car seems somewhat sluggish even more then before. NY was up in the 90s the last two days and this was when it seemed the worst. Any other day performance is fine. Should i be worried?
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
The fan is probably engaging more because of the heat, causing more of a drag on the engine.
 

pejeeper

Member
Jan 27, 2012
81
I was just thinking the same thing this week...I live in NY too and ran the A/C hard. I got too used to driving it with no A/C and now that I need it...powerloss. I usually cruise with windows down on the hwy, but this week I needed the TB around town and the loss of acceleration is quite noticeable. It dogs thru first and until upper end of 2nd gear and then takes off, shifts, then dogs until the mid range of 3rd gear and takes off again, shifts and has no noticeable loss afterwards until it drops a gear or two with traffic and lights. I'm assuming that's just the way it is...nothing to be done. I'm still getting 14.5-15mpg mixed driving with A/C on and being slightly heavy on the gas pedal.
 

MacMan

Member
Mar 3, 2012
194
pejeeper said:
....It dogs thru first and until upper end of 2nd gear and then takes off, shifts, then dogs until the mid range of 3rd gear and takes off again, shifts and has no noticeable loss afterwards until it drops a gear or two with traffic and lights. I'm assuming that's just the way it is...nothing to be done.......

Correct. The torque curve starts to pick up at approx. 3600 RPM....that's the power "surge" you feel.

It's one of the things that I think the engineers should have fixed....more low end torque. 3600 is pretty high for a "grocery getter" vehicle.
 

CaptainXL

Member
Dec 4, 2011
2,445
kjkim93 said:
seems somewhat sluggish even more then before. Should i be worried?

Ahah! More than before? Interesting. I have noticed the same symptoms. Perhaps we have a partially clogged converter? Shoot..still need to test that.
 

Simon01

Member
Dec 5, 2011
116
I don't think you have anything to worry about. AC robs upwards of 20 hp from your engine. Combine that with the high temps, making the AC run more often. It probably seems worse when you are driving around town at lower speeds. The AC works best when the engine is above 1,000 RPM's at least and when you are moving at a good speed to air is flowing through the condensor.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Simon01 said:
...AC robs upwards of 20 hp from your engine. ...
Through our little serpentine belt? Wouldn't have thought it was capable of transmitting that much HP. :confused:
 

ksimm92

Member
Apr 28, 2012
166
CaptainXL said:
Perhaps we have a partially clogged converter? Shoot..still need to test that.

I have noticed the same issue with my AC, one thing I have not looked into is the cat... how would I go about "testing" that?
 

ksimm92

Member
Apr 28, 2012
166
the roadie said:
Muffler shops can test the backpressure generated by the cat by drilling a hole upstream from it, or removing the O2 sensor from the exhaust manifold, and then installing a gauge temporarily.

That's good to know, I will be taking my truck into a local exhaust shop soon to have them weld and bend some pipes for me. I will probably have them look at it then. thanks!
 

Sparky

Member
Dec 4, 2011
12,927
Mine always is more doggish when the AC is on. I think it is a combined effect from the compressor and the fan. Sometimes if I know I'll need more power (like a really short entrance ramp) I'll kick off the AC for a moment. I don't think it is that abnormal, and I'm pretty sure my cat is OK as it runs normally otherwise and mpg is where it belongs.
 

NoeyBlaze

Member
Jun 25, 2012
5
My 03 trailblazer ls drives fine in the winter and heater works great, but in the summer it drives sluggish when the ac is on, thought it was just my truck with this issue
 

McGMT

Member
Jun 17, 2012
621
I have been thinking lately about retrofitting an electric fan onto the front of the A/C condenser so it works a little more efficiently and works better in slow traffic or stop n go spots.

Also, the cooler you can get the condenser the lower the pressure will drop on the high side, making your compressor not work so hard and cooling off your evaporator more efficiently lowering the amount of time the compressor runs to cool the interior.
 

NoeyBlaze

Member
Jun 25, 2012
5
McGMT said:
I have been thinking lately about retrofitting an electric fan onto the front of the A/C condenser so it works a little more efficiently and works better in slow traffic or stop n go spots.

Also, the cooler you can get the condenser the lower the pressure will drop on the high side, making your compressor not work so hard and cooling off your evaporator more efficiently lowering the amount of time the compressor runs to cool the interior.

:thumbsup: I was thinking of doing the same thing, just in case I see that temp getting hot past 210 from using the ac or just sitting in traffic during a summer heat wave
 

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