AC & Idle RPM Question?

[Ludigdrums]

I have an '81 that has all the emissions and computer removed. The AC works great, except when Idling around 5-600 RPM. When you increase that to about 1k, it's fine and cold.

I know with my '87 Monte Carlo that when you turn on the AC, it kicks up the RPM's a bit. Did the Vette have this also, but was attached to the computer? If so, how can I remedy this?

Thanks!

- Jeremy

 

[Bender]

I have the same exact problem, when sitting in traffic if I kick the AC on the engine will idle poorly and can sometimes die, but I have more problems then that so I dont know.

 

[Ludigdrums]

Hey Bender, sorry to hear you're having problems.

However, the difference with mine is that nothing changes at all. It idles completely fine, however, I think that when the AC is turned on, that it should make the idle higher. This way, running the compressor fast enough to do its job.

- Jeremy

 

[Bender]

How cold does your AC run, My runs cool but not cold and does Almost nothing when its this hot, I have so much heat comming up from under the dash its useless.

 

[Ludigdrums]

My AC runs cold 58-60 degrees, although not as cold as it maybe should ~50 degrees. When it's idling, it's just cool, not cold. Once the RPMs increase, it gets cold. I checked my low side pressures, and they are where they're supposed to be ~38-40.

I get the heat as well, but not while the AC is on. When the AC is on, the outside air vents should be shut, unless you have it on MAX.

You probably just need a recharge of R-12. I just used this stuff called Freeze-12 in my Monte Carlo, which is a replacement for R-12 and is pretty cheap on Ebay. Worked great! Real happy.

- Jeremy

 

[Bender]

It was just recharged, before it was even charged it was not cool at all. It has been checked for leaks and everything. But anyway? You think the computer use to kick the ac on when it would idle?

 

[Ludigdrums]

That's strange that it's not cooling...

What I mean about the computer is this: When you turn on the AC, the computer automatically raises the RPMs to handle the extra load of the compressor engaging. At least, that's how it is in my Monte.

So, that was my question...is whether or not our Corvettes are supposed to have this same function with the computer or not.

That help?

- Jeremy

 

[Bender]

I dont have a computer in my car either :/

 

[brusso]

I have an '81 that has all the emissions and computer removed. The AC works great, except when Idling around 5-600 RPM. When you increase that to about 1k, it's fine and cold.

I know with my '87 Monte Carlo that when you turn on the AC, it kicks up the RPM's a bit. Did the Vette have this also, but was attached to the computer? If so, how can I remedy this?

Thanks!

- Jeremy

On older non computer cars, there was a solinoid on the side of the carb. When the a/c was turned on it would "bump" the throttle linkage to increase idle speed. It also had an adjustment to it to give you the desired rpm.

 

[Ludigdrums]

Thanks Brusso...that's what I thought.

Now, the carb I have is a Holley w/elec. choke. Is there anyway to hook up an idle speed solenoid for the AC?

Thanks.

- Jeremy

 

[Tifton81]

Hey Guys, I have the same problem. I just installed a new AC Delco compressor and had it charged. It's where it should be but when the car is idel and I turn on the AC, the RPS'S dip. I installed a cut off valve on the heater line and that really helped the cooling but the idel is still to low.

Let me know if you find anything out.

Tifton 81

 

[Robin7TFour]

for the aftermarket carbs you have a few choices. one,edelbrock makes a solonoid and mounting bracket just for the a/c application.two, take the solonoid off your old q-jet and fabbed a bracket to make the holley,or edel.bump the idle up.


robin

 

[tomtom72]

Hi guys, Robin and Brusso have it right on the idle soleniod. You can use chevy's idle speed soleniod from 72 lt-1's. I had one and after rebuilding the motor I had the same problem. I used the solenoid by tapping it into the two wire harness going to the compressor, the one that activates the comp. clutch. If you look in the lt-1 forum you can find the thread with the part #. Just see if you can buy the bracket with it. I used the solenoid with a holley 4550 series carb. Also, remember if the A/C system is dirty it will not blow cold enough, even with a new charge. You guys may have the VIR system, my 72 had the POA system. There were lots of places for dirt to hide in that sys. As a rule of thumb I changed the Receiver-dryer every time the sys was opened up after I rebuilt it entirely. NO dirt=cold air...duct temp of 45 degrees. In a VIR system there are less parts to change, and it has a orifice filter in the thing that took the place of the Rec-Dryer and the POA and Expansion valves. The only problem is you need to suck down the system to do it right, and run a cleaner throught it and then replace the parts that catch the dirt, suck it down again,and recharge it with the tanks that have the oil. Hope this helps. tt72

 

[Bob Chadwick]

Those temps are too high. I converted mine to R-134 and blow about 40 degree air when moving. In stop and go traffic it gets warmer, somewhere around 55 degrees.

NOw if the fan would just blow the air hard enough that it would come out of the vents and blow on me. :L