AC idle advice

[Sonny]

I finished the complete replacement of my AC system and it cools great! I bought a can of AC Pro from Walmart and that’s all I used to charge it.

How much idle increase do you guys use with AC on in the summer? I know the clutch engages the compressor thus lowering rpm, but mine really shakes and the 2 belts from the alternator to the AC bounces up and down about an inch when ac is on. Is that normal too? Smoothes out with increased rpm.

 

[Dennis H]

750 year round. There is a detectable bump/click when it cycles, but not significant.

 

[493 Mike]

View attachment 603184 I finished the complete replacement of my AC system and it cools great! I bought a can of AC Pro from Walmart and that’s all I used to charge it.

I'm confused. How many ounces of refrigerant did you use? How long did you evacuate the system?
Mike
PS: You obviously need a big stroker motor to carry that load!!!!!!!!!

How much idle increase do you guys use with AC on in the summer? I know the clutch engages the compressor thus lowering rpm, but mine really shakes and the 2 belts from the alternator to the AC bounces up and down about an inch when ac is on. Is that normal too? Smoothes out with increased rpm.

 

[Sonny]

Don’t know the ounces, but filled it till the gauge was in the green/full zone.

Did not evacuate. All new parts. Is it required?

AC was on the 318 2 barrel. Swapped for a 360 4 barrel. Would think thats enough engine.

 

[RJRENTON]

Sonny,
Re evacution b4 vharging AC system.
The purpose of evacuation is two fold. It removes any moisture that may have entered the system when the components were disconnected....hoses, fittings and the receiver/dryer assembly. The dryer can only absorb a small amount of moisture (water vapor)...maybe 100 GRAINS of moisture (approximately less than 1/8 of an ounce). Moisture will cause a corrosive acid to form in the system and ultimately component failure (compressor reed valves). The other reason for evacution is to remove AIR which is a NON-CONDENSABLE compared to refrigerant which is a condensable. Air accumulates at the top of the condenser and inhibits the condensing rate of the refgerant which will ultimately affect the system's cooling capacity.
My advice....evavuate the system to 200 microns (+29.92 inches of mercury) to insure that all the moisture and air are removed. I'm sure others will have their own opinions.
Bob Renton

 

[oldbee]

Sonny,
Re evacution b4 vharging AC system.
The purpose of evacuation is two fold. It removes any moisture that may have entered the system when the components were disconnected....hoses, fittings and the receiver/dryer assembly. The dryer can only absorb a small amount of moisture (water vapor)...maybe 100 GRAINS of moisture (approximately less than 1/8 of an ounce). Moisture will cause a corrosive acid to form in the system and ultimately component failure (compressor reed valves). The other reason for evacution is to remove AIR which is a NON-CONDENSABLE compared to refrigerant which is a condensable. Air accumulates at the top of the condenser and inhibits the condensing rate of the refgerant which will ultimately affect the system's cooling capacity.
My advice....evavuate the system to 200 microns (+29.92 inches of mercury) to insure that all the moisture and air are removed. I'm sure others will have their own opinions.
Bob Renton

+1 definitely! It’ll probably shake a little more with a small block behind it; no biggie.

 

[bearman]

I agree with Bob. All system must be evacuated to have a/c you are pumping air and will hurt compressor pretty quick

 

[Sonny]

I agree with Bob. All system must be evacuated to have a/c you are pumping air and will hurt compressor pretty quick

Thanks all. I’ll chalk up the $30 ac can as a “test” purchase and take it to a pro.

 

[PurpleBeeper]

Yeah, these guys are right about evacuating the A/C. On your A/C idle issue... is there a way to install an electric idle solenoid? Six packs and mid-late 70's cars had them stock. Maybe you could wire it in with your A/C system (instead of off the ignition coil) so it would bump up your idle only when you turn on the A/C?

 

[bearman]

A/c only drags down for a minute while clutch is kicked in. Then it should go back to steady 750 idle. You will depend on low and high pressure cut out switches to control your a/c. If you have electric fan for the condenser this will help pull down temp and won't drain so hard on the engine.

 

[5.7 hemi]

By pulling a vacuum it will boil out any moisture in the system. Once that is done, you can refill to spec.

 

[bearman]

Sonny do you have adjustable low pressure switch on the car

 

[66chargerpat]

Back in the 80's, my brother had a 360 van with the same thing. Your belts have to be as tight as ****! We added a idler pulley on the back side of the belt between the alt. and crank pulley. That stop it.
Zorry 4 speelen. pat

 

[bm02tj]

With all the air still in the system your high side will be high and will also help with this problem
As the piston has to try to compress air and higher temp freon as condenser is full of air

 

[YY1]

FSM spec is different for AC and non AC cars.

I want to say my 73 calls for 50 RPM increase.

Mine is at 700 and is fine with the clutch not engaged, but does drop 50.

I've been harvesting solenoids and hook up should be easy (just tap the clutch lead) but mounting looks like it's going to be fun.

Plus it's kind of hard to tell the diff between an AC solenoid and an idle stop.

 

[SureGrip]

Sonny,

Did you convert your system to run on R-134 VS the original R-12? To my knowledge, AC Pro only comes in R-134 (R-12 being nearly unavailable at this point), and the two refrigerants are not compatible. The R-134 molecule is much smaller and requires different o-rings and hoses, otherwise the refrigerant will just slowly leak from the system.

 

[Sonny]

Sonny,

Did you convert your system to run on R-134 VS the original R-12? To my knowledge, AC Pro only comes in R-134 (R-12 being nearly unavailable at this point), and the two refrigerants are not compatible. The R-134 molecule is much smaller and requires different o-rings and hoses, otherwise the refrigerant will just slowly leak from the system.

Yes. New compressor, evap, dryer, condenser, expansion valve, etc. only saved the 2 hoses and cleaned them with ac cleaner.

 

[Johnpat]

Check to see if you need to add any oil also.

 

[JimKueneman]

If it is 134a then don't fill it until the bubbles in the sight glass stop. It needs about 30% less than R12. The only right way is with gauges to get it right.

 

[bearman]

Jim what are the pressures reading at 30%less. That is interesting that it will do what you want running with less. I have done it both ways and came out with larger load working best. But doesn't mean I'm correct in my thought pattern