RPM's go up when A/C kicks in. | Ford Explorer Forums - Serious Explorations

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RPM's go up when A/C kicks in.


Active Member
May 31, 2007
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Santa Maria CA
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Just like the title says the RPM's go up when the A/C comp kicks in, then go back to normal when it is off. Any ideas guys, BTW this site rocks!

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But it never did this before untill last week, and it goes from like 800 rpm to 1300 when a/c kicks in and back down.

im sure it wont hurt anything.

My Ex started doing this exact thing, but it only does it whent the temp outside has been over 100 degrees Farenheight. We have been above average in temp for the last couple of days here in East TN and I noticed this when I was driving when it was over 100, but not when it was in the mid 90's. Could the A/C be a little low or is it just the amount the compressor is switching to cool during the extra-hot weather?


As indicated, its normal... probably... but it doesn't explain why it just started happening .... 10 years after it was built...:-) Some idle adjustment is normal but the degree of adjustment it based on sensors and your IAC.... maybe a cleaning is in order. I think the sensor that has a major impact on engine speed is temperature sensor (for the computer... not gauges).... maybe its not functioning and vehicle "thinks" its cooler that it really is.... resulting in a richer setting during the AC kick in... just a guess though.

...what he said, lol...plus my ranger is doing the same thing since it's been 100 forever down here...it wouldn't hurt to clean your air filter, iac, and such...with that fire burning for the last what, 5 weeks, there is alot of foreign contaminents that need to be removed...when i got back from pismo the wind shifted and you can see it in the air...i hope this helps...:D

I am suspecting that my IAC is bad. My Ex had 144800 miles on it, and believe it or not it is %99 factory. Transmission and IAC and the entire front end is still working acceptable so I haven't changed anything yet. The IAC was not allowing the EX to start so I did what I always do and clean it with some carb and choke spray. But after a week from cleaning it, it is still a little hard to start. The plunger inside is getting tight even after it was cleaned so I was hoping it would break free but I guess it is finally time to replace it. I will report back if changing the IAC fixes the reving issue.