A/C works, but now rough idle

[Rhino FJ60]

OK, got a newer A/C compressor in and charger it. A/C works now, but not when idling. I have to rev it manually to about 1,000 to get it to kick on. When I do have the A/C is on, the RMP's drop, it runs rich and sputters at idle and while driving. I know I am missing something simple. Kind of sucks because now I have A/C, but when I use it, the thing runs like crap. Any help would be much appreciated! BTW '84 FJ60

 

[Joe Egolf]

a/c

low refrigerant?? Vacuum leak??? I presume it ran fine b4 puting a/c in ??

 

[inkpot]

Howdy! Should be a high idle kick up solinoid to raise the idle when a/c is on. Is engine recently tuned up? May need to tweed timing a bit? John

 

[Rhino FJ60]

Yes, ran fine before and now only runs poorly with it on. I will check the system again, but I think pressure is fine and holding. So, low refrigerate can make it the vehicle run rough?

 

[Rhino FJ60]

Yes, timing was fine, new cap and rotor, plugs, and wires about 6 months ago.. It has always seemed to run a little rich, but with A/C on it runs real bad. BTW, where is the idle kick up solenoid? Thanks

 

[NocalFJ60]

If you just changed the compressor and it runs rough, it seem like the carb idle up setting on the front of the carb is good. It is just taking more power to turn the compressor now and the engine is unable to keep up with it now. I think low freon can make compressor work harder. That is why there is the pressure switch to not let the compressor come on when the system is dead and kill the compressor from what I understand.

Check the idle up diaphragm on the front of the carb. Maybe the solenoid on the fender that gets vacuum from the intake manifold when you turn on the AC is opening the intake manifold to air which is causing a vacuum leak only when you turn on the AC. Check the diaphram on the front of the carb to see if it leaks.

 

[2mbb]

There is a vacuum actuator mounted on the front side of the carburetor. This actuator pulls the throttle open. There is a screw on the front of the throttle shaft that is used to set the AC idle speed. When the AC compressor turns on, a vacuum switch on the drivers side fender well opens to apply manifold vacuum to the actuator. This should be set to raise the idle speed from 650rpm up to about 1000 rpm. If you set the screw too high, the rpm will surge up and down.

Then, inside the passenger compartment under the dash board near the glove box is the AC amplifier. This has a blue knob on it that used to adjust the minimum idle speed the compressor turns on. Once you get the AC idle speed actuator working, if the compressor isn't engaging, then turn the knob until it does.

 

[inkpot]

Howdy! Was this a do it yourself project? If so, did you vacuum flush the system when it was open, are you running R12 or 134a, how many pounds of freon did you put in, did you add any oil to the system? Is this OEM originally on the rig, or was it added later? John

 

[Rhino FJ60]

Yes, DYI job with recharge kit (134a) and did not vacuum flush. I think about 2 cans (2 lbs) of oil and freon. Thanks again.

 

[Rhino FJ60]

Just to tie this one up, yes it was the vacuum actuator- the bottom hose was going into some random tube. This is the 4th vacuum line that I have located that was hooked up incorrectly since I bought it. The old engine crapped out and this was a used one the mechanic apparently didn't install correctly. Thanks for the diagram 2MBB- did the trick. A/C is ice cold and I have my winter and SUMMER truck now. Gotta love this forum!