C% ac issues after underdrive install
Thread Starter
Cruising
Joined: Sep 2021
Posts: 10
Likes: 0
From: Winnipeg
C% ac issues after underdrive install
good afternoon guys,
i have had low AC performance ever since i had my underdrive installed. My ac mechanic has figured the pulley is the issue. my ac light usually is green when operating, but it shuts off at lower RPM and i have very little cooling. In summer its almost undrivable.
is there a kit available to speed up the AC RPM?
i have had low AC performance ever since i had my underdrive installed. My ac mechanic has figured the pulley is the issue. my ac light usually is green when operating, but it shuts off at lower RPM and i have very little cooling. In summer its almost undrivable.
is there a kit available to speed up the AC RPM?
Drifting
Joined: Sep 2022
Posts: 1,451
Likes: 1,114
good afternoon guys,
i have had low AC performance ever since i had my underdrive installed. My ac mechanic has figured the pulley is the issue. my ac light usually is green when operating, but it shuts off at lower RPM and i have very little cooling. In summer its almost undrivable.
is there a kit available to speed up the AC RPM?
i have had low AC performance ever since i had my underdrive installed. My ac mechanic has figured the pulley is the issue. my ac light usually is green when operating, but it shuts off at lower RPM and i have very little cooling. In summer its almost undrivable.
is there a kit available to speed up the AC RPM?
Fix is to change back to the stock balancer without the underdrive.
Or, decide that the poor a/c performance is worth the small amount of HP you picked up with the underdrive pulley, and live with it.
Le Mans Master
Joined: Jan 2001
Posts: 5,012
Likes: 508
From: Hilton NY
The compressor could be on it's last legs, you don't say how old your car is or the miles on it. Two years ago my '98 wouldn't cool down even though the charge level was correct, the orifice tube was clean and the compressor was spinning. I bought a kit from RockAuto for about $500 and after those parts were installed the plenum discharge air is usually 36 degress F now. This is with the stock drive ratio, I don't recall anyone complaining about poor AC performance who had an underdrive damper.
Melting Slicks
Joined: Feb 2025
Posts: 2,103
Likes: 2,027
From: THE BEACH..
Find someone to turn the Idle RPM up in the Tune. Everything I've built with UD Crank Pulleys had a pretty good size Cam in it to where the Idle was atleast 700 RPMs. Never had AC problems with UD Pulleys with the Idle turned up.
Pro
Joined: Dec 2014
Posts: 683
Likes: 275
From: Cincinnati Ohio
A simple way to determine if it is the slower compressor pulley ratio is to drive in a lower gear. On a hot summer day, drive at 30 mph in whatever gear you normally do. Then drop down a gear. If you feel cool and comfortable in the lower gear, then your pulley drive ratio is probably it. If no noticeable difference, then you need to trouble shoot your a/c system.
If you poor a/c performance is only at idle, then do the same experiment at idle with normal idle rpm and then raise the idle rpm about 200.
If you poor a/c performance is only at idle, then do the same experiment at idle with normal idle rpm and then raise the idle rpm about 200.
