A/C function at idle.... (1 Viewer)

[MrZero]

So after 4 years of never running the A/C (truck sat dead) and the past two years since with no working A/C (no freon in system), I finally broke down and converted to R134. I had a local garage around the corner do it for around $350. All components checked out and the standard drier\oring\fitting changes were made. No leaks yet and there's already dye in the system in case one develops. It's cold. Nice and cold. It's also pretty damn loud for some reason. The problem I'm having is that at idle at stop lights, the temp coming out of the vents rises considerably, and then gets very cold again once I start moving or if I race the engine a bit. Is this normal operation or should something be "kicking in" when I'm at idle? I swear I remember that six years ago, I'd hear something click when at idle and the rpms would actually climb like the idle was faster............

--JP

 

[Zack1978]

There is an adj knob under the dash on the pass side. I think it is blue. YOu can adj the knob to allow it to work at idle. I THINK!

Zack

 

[swank60]

There is some sort of throttle control for the AC. For the life of me, I can't seem to find any info anywhere on how to manipulate or set it up. Not in the Haynes, not in the FSM...there's a screw on the front of the carb that raises the idle speed for the AC, but on mine, there's nothing attached that disengages it's input if the AC isn't on - so the idle is way up.

So there you go - I have no idea either.

As for the noise, keep an ear on it for a while. The noise should settle down. If it doesn't, you need to take it back to the shop and have them check the amount of oil in the system. When I converted mine, it was pretty noise, and after a little fiddling and oil additions, the noise settled down. Thing is, you don't want too much oil, of you'll loose your cooling. Another thing that causes the noise is too mcuh pressure in the system - but if it's cooling well, you should be okay. If the noise increases or changes, or if you really are concerned about it, take it back to the shop. You might consider giving them a call about the noise anyway.

 

[dd113]

On the DS fender just in back of the headlight washer tank is a VSV for the AC. When you hit the AC switch this allows vac to suck on the dashpot on the front of the carb and raise the idle. The screw mentioned above determines how much additional idle you get.

I cant remember for the life of me what the rheostat under the dash does, I think you turn it to adj how often the compressor kicks in but I could be way off.

 

[wingysataday]

I adjusted that thing under the dash all the way and my A/c still turns off when I'm stopped.

 

[chitown40]

This was just covered a few times, but here's the skinny again anyway:

Under the passenger side dash (under the glove box) is the a/c amplifier which controls the cut-off RPM. Per the FSM the cut-off RPM should be between 600-700 RPM. If the cut-off RPM is too high, turn the adjusting knob clockwise to adjust.
If the cut-off RPM is too low, turn the adjusting knob counterclockwise to adjust.

The info on the idle-up solenoid that dd113 mentioned is correct. As far as I can tell there is no specific RPM to adjust the a/c idle-up speed to. I adjusted mine to about 900-1000 RPM when the compressor kicks on. This tends to keep the volt meter steady.

From what you described in your original post, I think all you need to do is adust the a/c amplifier under the dash.

 

[MrZero]

Thanks guys! I'll try adjusting the A/C amplifier. Sorry if this was redundant, I tried searching before I posted since air has been a hot topic on this board this summer......but I guess my search skillz need polishing! Oh, and BTW, the noisiness has pretty much gone away. The best part about this is that now I don't need to choke to start....with the AC button on, she starts right up on the first try.

--JP

 

[chitown40]

I think I would go back to using the choke instead of adding more load to your electrical system and the engine itself. Might be more "fun" to just have an illuminated push-button choke per se, but not the best of ideas IMOP. Glad you're working again though...

 

[swank60]

I think I would go back to using the choke instead of adding more load to your electrical system and the engine itself. Might be more "fun" to just have an illuminated push-button choke per se, but not the best of ideas IMOP. Glad you're working again though...

Agreed. If you put too much load on your electrical system at startup, you could fry a fusable link or your alt.