Increasing rpms with AC on

93CalypsoConvert

Active Member

Nov 26, 2020

275

91

38

Virginia

Sep 18, 2021

#1

• Sep 18, 2021

• #1

Is there anything I can do to increase my idle rpms while my AC is on? My idle sits between 600-700 rpm, but when the AC is on, it drops to 400-500 depending on the temperature of the engine. I feel like the thing is about to stall, and at that low of rpms my alternator barely even charges. It is carbureted, so I considered finding a 12v solenoid to push the throttle open while the AC is on to make it idle up. Anyone have and ideas to make it idle up?

 

B

Black GT

Active Member

Sep 8, 2018

148

9

28

Jacksonville, Florida

Sep 18, 2021

#2

• Sep 18, 2021

• #2

The ECM is supposed to increase rpm's when the A/C is on. Not sure what or where the sensor is that tells it to do this.

 

KRUISR

10 Year Member

Apr 16, 2015

1,802

903

143

Sep 18, 2021

#3

• Sep 18, 2021

• #3

ECM uses the IAC to bump the idle. But being carbed, I would think the only thing to do would be increase idle. I know stock idle is usually around 800-900. Try increasing your idle and see if it helps with AC on.

I also know that 600-700 has a nice old school lope.

 

Reactions: 93CalypsoConvert

General karthief

wonder how much it would cost to ship you a pair

5 Year Member

Aug 25, 2016

27,865

10,537

203

polk county florida

Sep 18, 2021

#4

• Sep 18, 2021

• #4

The carb'd setup uses a solenoid to kick up the rpms a little, look to a ac manufacturer like Classic Air for a ac stepup solenoid.

 

Reactions: Ranger and manicmechanic007

manicmechanic007

5 Year Member

Sep 26, 2017

2,526

712

143

Roy, Utah

Sep 18, 2021

#5

• Sep 18, 2021

• #5

The general is right
The carb'd a/c car would have had a stepper motor bolted to the throttle plate
These shorted out on a regular basis and I threw away several
You should be able to find one and they work well
They just got power thru the ac clutch coil circuit

 

Reactions: Ranger and General karthief

90sickfox

Wasn't a pretty sight...and I've got big hands

SN Certified Technician

Mar 2, 2015

6,945

5,816

213

Sep 19, 2021

#6

• Sep 19, 2021

• #6

I used to take the stepper motors off of mid 80s cadillacs in the JY. They worked well to increase rpm. They are easy to fab to work. I'd use a relay triggered by the the low pressure switch.

 

Reactions: General karthief