A/C dragging on the engine?

[Brandontw]

hey guys im back for another helping of your tasty wisdom. My 92 MTX runs fairly well and doesnt have any glaring problems seeing how its got 183000 miles on it, but there is a thing thats bothered me scince i got it a few months ago. When i am driving down the road with my a/c on the compressor seams to drag on the engine ways to much, it kicks on and i can feel the whole car slow down then speed back up again whe it kicks off it is so unbearable that i do not use my a/c anymore and its been really hot! i turn the a/c off and it seams to pretty muck stop buth there is something else that comes on and off that i think i can barely feel when im driving. and i can here it when the car is in idle and i have my head under the hood. it just sound like normal car noises, but it seams like it should not affect the performance of the car. im not a very experienced car guy, i just know the basics, so go easy if i said somthing stupid

 

[sdpatt]

The A/C compressor adds about a 10 hp drag on the engine when the clutch engages. You will be able to feel this on an engine that is only generating about 40-70 hp to cruise down the road at highway speeds.

Now, how often is the compressor cycling? If it is more often than about 30 seconds between engagements? That could point to low refrigerant pressure. If that is the case, it would be a good idea to check the pressure.

If it is staying engaged and not cycling at all, there is a chance that there is too mich pressure in the system. That would cause a larger load on the engine than it would with the normal charge.

 

[Rob94]

Get used to it. Sadly, the AC compressor puts quite a drag on the engine. Like Scott said, you will notice it during "normal" driving. Small price to pay for comfort though IMO.

 

[Brandontw]

ya im sure my coolant pressure is low because my a/c is just "cool" not cold and the compressor kicks on and off like crazy, thats why its unbearable for me,it practically makes me seasick.

 

[shojuan]

At least get a low side gauge. If you can swing it get a nice gauge set that has low and high side gauges.

With gauges you can see where you are at chargewise, and also where you need to be. Plus you can monitor things while getting there.