I drive a 99 Jeep Grand Cherokee I-6, why would my RPMs fluctuate when I am driving under normal highway driving conditions, and it usually happens when my defrost is turned on....the revs would pulse from 2000-2400 or so, with no increase in speed...just engine revs.
2007-02-10 04:53:12 · 4 answers · asked by Jas 1 in Cars & Transportation ➔ Car Makes ➔ Jeep
If you're on the highway and your engine goes from 2000 to 2400 rpm your speed should jump up by 30MPH. But since it doesn't you have a short in progress somwhere. Get it checked out soon because if the short is before the computer it could screw up your milage or worse.
2007-02-10 23:21:08 · answer #1 · answered by jeepnuk 4 · 0⤊ 0⤋
When the defrost is on, the system cycles the air conditioning to remove some of the moisture from the air. What you are noticing is the change in engine speed from the A/C compressor turning on and off. My 02 Kia Rio does the same thing, but is more severe since the A/C takes engine torque to run it, and my Rio doesn't have much power to begin with.
2007-02-10 12:58:19 · answer #2 · answered by Doug K 5 · 0⤊ 0⤋
when you have your defrost on it cycles your air conditioner compressor and when it cycles on it revs up your rpms. the reason the compressor cycles when you are in defrost is so it can help eliminate the moisture on the window.
2007-02-10 12:58:56 · answer #3 · answered by george 2 6 · 0⤊ 0⤋
most likely your a/c compressor kicking on. it kicks on in defrost to remove humidity out of the air in order to defrost/defog the window.
2007-02-13 10:00:17 · answer #4 · answered by mj 2 · 0⤊ 0⤋