I just put in a new long block and have about 35 miles on it. I previously adjusted the idle and it sit perfect at 850-900 rpm. Today it is warm so I turned the a/c on. The idle dropped to 450-500 rpm. I noticed when I turn the a/c off it goes back to 850-900 rpm. Obviously the a/c does put a load on the engine which causes this. Anyway to make it work right? Thanks.

BTW '93 4wd pickup w/ a 22RE and manual tranny.

 

AC steals power, cut it out of the system and open your windows. Mpg's AND fresh air, depending on what smog is like on the bottom coast.

 

There is an Ac idle up valve that ups the idle when the Ac is on it sits up on the valve cover.

Could have been misplaced when you swapped in the engine and didn`t get hooked up.

or it just quit working

The way it works it just gives the engine more air when the ac is on keeping the idle

If it was me I would rather be comfortable then lose power with the windows open

 

I had to read that a couple times for it to make sense. But I heard what you meant.
To each his own, but I've been plenty comfortable with the windows open or half doors on. I also understand the want for both creature comforts and wanting things to work correctly in your rig. Best guess is that through the swap, the control valve was overlooked, or as suggested before, doesn't work.

Also, see this thread. It should help you to determine the state of your a/c system.
https://www.yotatech.com/forums/f116...dle-up-141895/

Good luck!

 

so if your rpms drop say 100 to 150 is that okay ?

 

In a 22re (I don't have experience with any other engines) I wouldn't worry about 150rpm, as you would still be at 700rpm if you idled correctly. What the OP describes is a drop of 400 rpm, which would worry me that my idle was in the 450 range.

 

Thanks for the info. Will find the a/c control valve and check it out. I bought this truck back in November and never used the a/c other than to see if it was working before I bought the truck. The truck also idled at about 1600rpm when I bought it so would not have noticed a drop anyway. I have the shop manual so now I know an a/c control valve exist I will know what to look for.

 

Keep in mind, an A/C control valve and an A/C idle up valve are different things, and the guy at the autozone parts counter doesn't know the difference.

 

I want to make sure I am looking at the right thing. I looked up the A/C portion of my shop manual and it has a VSV (Vacuum Switching Valve) that fits the description of what y'all are talking about and the link that was provided by Boon. I looked at my vavle cover and found what I believe is the VSV. It is a rust colored brown box with a brown electrical connector. It has 2 vacuum lines, one with a small in-line air filter. On the other end of the rust colored box/switch it has a black, smooth cylinder which you can turn easily with your fingers. Is this black, smooth cylinder the adjustment screw? If so would I just get the truck up to normal operating temps & rpm then turn on the a/c and adjust this knob until the idle works properly w/ the A/C on (assuming the VSV is working properly to begin with)?

 

ac idle up thing is a white screw on top of the intake

 

Exactly.

 

OK. Looking at the first picture in the link Boon posted https://www.yotatech.com/forums/f116...dle-up-141895/ I was able to find it. My screw is black, not white. Maybe it has been replaced along the way. I will fool with it tomorrow and see if it has any effect.