--Resolved-- a/c compressor cycling rapidly, can't figure this one out
08-03-2012, 01:19 PM
#1
--Resolved-- a/c compressor cycling rapidly, can't figure this one out I found a little info by using the search, but not what I was looking for. Recently did heads and cam and got the car tuned. It idles fine with no a/c, but the compressor cycles rapidly at idle when turned on. If I increase the rpm the compressor will stay on. It only acts up at idle.
I hooked up the HP Tuners scanner and commanded the a/c clutch to engage while idling and it works perfectly when commanded on. As soon as I let return it to the car it starts cycling again.
I hooked up a can of 134+ (with built-in gauge) on it and it won't give me a correct reading at idle because the compressor is cycling so fast. I tried adding 134 anyhow and it didn't help the issue.
The cars idles great when the compressor stays on, but due to the constant cycling the idle surges up and down. Any ideas?
I hooked up the HP Tuners scanner and commanded the a/c clutch to engage while idling and it works perfectly when commanded on. As soon as I let return it to the car it starts cycling again.
I hooked up a can of 134+ (with built-in gauge) on it and it won't give me a correct reading at idle because the compressor is cycling so fast. I tried adding 134 anyhow and it didn't help the issue.
The cars idles great when the compressor stays on, but due to the constant cycling the idle surges up and down. Any ideas?
08-03-2012, 06:30 PM
#5
Probably the low pressure switch. You're brute forcing the clutch with HPTuners, bypassing the switch input. What you really need to do before you do anything else is hook a manifold set to it and verify your pressures are correct while the car is off. If the high and low pressures read right then I'd suggest you force the compressor on again and verify the operating pressures are correct. If all the pressures check out both times I'd start by replacing the low pressure safety switch.
Best of luck.
Best of luck.
08-03-2012, 06:39 PM
#6
Easiest way to check the low pressure switch is to unhook the LP switch, use a paper clip and jumper the wires. Only do this if the LP switch has two terminals. If it has more disregard my last.
If it is the switch it will stay on continuously. As mentioned using a set of gauges is the best way.
If it is the switch it will stay on continuously. As mentioned using a set of gauges is the best way.
Trending Topics
08-05-2012, 09:32 PM
#9
Launching!
iTrader: (2)
Join Date: Dec 2011
Location: Cincinnati, Ohio
Posts: 241
Likes: 0
Received 0 Likes
on
0 Posts
Sounds most likely to be a low charge, which will not produce sufficient suction pressure to activate the lp switch, or the switch itself. Since it stays on when you give it throttle, I am leaning toward low charge. Just like everyone else already said, some gauges will do a lot of justice here.
08-06-2012, 08:12 AM
#10
I am going to replace the switch and see what happens. I was not able to jump the switch because it has 3 wires. But I did unplug it and the a/c stopped switching. If that doesn't fix it then I will take it to a buddy that is an a/c guy.
08-07-2012, 08:33 AM
#12
Staging Lane
Join Date: May 2012
Location: austin, tx
Posts: 96
Likes: 0
Received 0 Likes
on
0 Posts
It is low on freon, it is trying to turn on but when it does it finds it doesnt have enough pressure in the system so it turns off automatically. Go and have the system evaced and recharged, those junk cans you buy from the auto store that only hook to the low side are just that junk!!! They are not accurate and you need to know the high side pressures as well.
08-08-2012, 07:44 AM
#14
On The Tree
Join Date: Apr 2007
Location: Bloomington, MN
Posts: 165
Likes: 0
Received 0 Likes
on
0 Posts
Id be interested to hear what you find out. I read this thread yesterday and after having my car torn apart for a couple days, i took it out for a drive and it did the exact same thing. Never happened before and now its not doing it anymore. Hopefully a low charge - I do enjoy my AC...
08-31-2012, 09:34 AM
#16
For those that are interested, the a/c checked out just fine. It appears to be tuning related. Seems the IAC is not handling air flow correctly when the a/c is switched on. The a/c shuts itself off when the idle parameters are unstable. I should be able to fix it with a little HP Tuners time.
09-04-2012, 08:57 AM
#19
Ok thanks to JimmyBlue I got it resolved. I simply went into HP Tuners and zeroed out the tables for Stall Saver. Apparently this function will disable the a/c clutch when it thinks the car might stall out. Since the idle was a little unstable with the a/c on, it was turning off the a/c clutch and then allowing it to come back on when the idle would recover.
