AC and idle problem
07-21-2016 | 12:00 AM
#1
Guest
Posts: n/a
AC and idle problem
So I am new to this site as a user anyhow. I have just recently purchased a 1998 dodge cummins 12 valve. The truck has 261k miles on it but my uncle said they call this one the "holy grail of cummins" or the "million mile motor" I don't know about all that but I love the dang thing so far. I lost AC to my vents except defrost and on the feet, and I've noticed when the truck is in gear it idles funny (a lot of vibration) and it stalls out but only if the AC is on I got it to blow through the vents but if the AC is off the truck won't stall like that and idles find. I don't know for sure but does this sound like a vacuum problem or something more serious?
07-22-2016 | 08:07 AM
#4
Administrator
Joined: Jan 2007
Posts: 8,372
Likes: 172
From: Streator Illinois
Vacuum comes in a single line from the vacuum pump in front of the PS pump and runs to the drivers side of the cowl. There it Tees off to the various locations. It is VERY easy to get it disconnected at the T even with a simple job like changing the fuel filter.
I would say 90 percent chance you will find it between the pump and that T.
I would say 90 percent chance you will find it between the pump and that T.
07-22-2016 | 08:28 AM
#5
Registered User
Joined: Feb 2013
Posts: 147
Likes: 11
Mine had the funny idle problem as well. It would lope like it had an aftermarket cam when idling in drive with the AC on, and the idle speed was probably around 450-550 rpm. It would cut off if I let off the throttle suddenly, like in parking lot situations. The idle adjustment screw is a bit tricky to locate. It's on the driver's side, towards the back of the engine. There are some videos of this task on youtube.
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