i've noticed after my h\c swap that my A\C compressor clicks on and off when the car is idleing in park


once i start driving the car is fine but again at idle (1000 rpms) the a\c wont consistently stay on????


is the because of the underdrive pulley or sometihng to do with the big cam???

 

Its supposed to.

 

it suppose to click on and off constantly while at idle ?????

i mean the thing clicks on for 2 secconds then off for 2 secconds then back on again

 

could it be my idle is a bit high so its tring to click on but is still just low enough to turn it off?

if so how can i move that on\off threshold up?

 

if it hasn't been messed with, than the stock AC compressor will stay on until 4600 rpms are reached. Sounds to me like there is something else wrong than that... the system may be low on freon and the compressor does not detect enough pressure to keep the compressor on without damaging it...

The faster the compressor spins the higher the pressure in the system...

you'd have to be pretty low though...

hmmm....

 

In Hptuners I Have The Ac Set To Turn Off At 4000 Rpms And On At 3500 But Like I Said This Is Only At Idle (1000 Rpms)

To Recap The Unit Can Be Heard Clicking On And Clicking Off Id Say Every Few Secconds While At Idle In Park Or Netural .. Im Not Too Sure If It Does It In Drive But I Do Know Once You Kit The Gas It Goes Away

As Far As Freon Goes We Never Drained It For The H\c Swap So I Dont See Why It Would Need To Be Charged ??? Mabye A Leak ?? Is There A Easy To Check Freon Levle?

 

Anyone Else?????

 

There's a pressure sensor on the liquid line going into the a/c "box" by the firewall. Unplug that and see if it changes it's manners at idle. If it does, you have a pressure problem. I believe that switch senses high and low pressure (3-prong connector). The high pressure alarm tells the fans to kick on (you can actually unplug it, jumper 2 of the connections together, and poof the fans come on).

You can hook guages to the system at the ports, run the car with the a/c on and check the pressures. The suction pressure (low side, connects at the accumulator/drier) should be around 35psi IIRC.

 

You Dont Actually Hear Fans Turning On And Off Just This "click" Noise That Is Suppose To Happen 1 Time When You Turn On And Off The A\c

Also Its Causing My Motor To Surge A Little

As Far As The Fans Go They Seem Just To Stay On Consistantly (cau Usally Runs In The 190's And The The Hi Temp Fan On Is 185


Im Not 100% Sur Ewhat The Clicking Noise Is I Just Know It Happens Only When The A\c Is Turned On And It Sounds Like Its Comming From The Compressor .. To Give You An Idea What Im Talking About From Inside The Car Is Almost Sounds Like A Single Spark Knock That Is Happening Every Few Seconds At Idle But Its Not That

 

I was just throwing out that info about the fans, not saying it has anything to do with your problem. You can get under the car and watch the compressor, if the center is spinning on the clutch, it's on. What I'm trying to say is that it probably has correct pressure when the system is turned off due to the equilization in the lines, but when you turn it on, the pressure doesn't climb high enough and the computer says "not enough freon, turn this bitch off before it burns up".

Unplugging this sensor will either fool it into thinking it's fine, or not let it come on at all. If it won't come on at all, then it can't be used to diagnose the problem unless you jumper the connections inside the plug. To fool the compressor into working.

Right now I'm going with pressure problem.


BTW - Why in the hell is every one of Your Words Typed Out Like This? We normally only capitalize the first word of a sentence.

 

its a side effect of keeping caps lock on...i dont do it the computer does it somehow


also if the freon was low why would the a\c run when not at idle and only do this during idle times?

bTW thamks for the help this is really bugging me

 

It won't run at idle because there isn't enough pressure. Just as natronathon said, when the compressor spins faster, it generates more pressure in the system.

 

OK so im guessing that since my car idles arround 900-1200 rpms that mabye its turning off and turning of because its right on that on\off threshold???

for example: its just barely reving fast eough to turn the compressor on but not enough to keep it on .... so it keeps cycling on and off ????

also i do have a powerbond underdrive crank pulley

 

Correct me if im wrong, but isnt the compressor supposed to cycle on and off?

 

There are some systems that use a "cycling clutch" method of keeping the low side from freezing up, but lately most cars have switched to an expansion valve or variable displacement compressors. To be honest, I don't know what type the late model F-bods have.

 

Turning the compressor on/off is independant of engine RPM. If there is low pressure, it will not allow the compressor to stay on and burn up. I have to go with TheBlur that you are low on Freon. Go to the autoparts store and pick up a can of R134a refrigerant and put it into the system and see if it helps any.

It isn't anything to do with your "big" cam, or the underdrive pulley. There's plenty of people here with the same and bigger setups that don't have any problems. Your problem lies elsewhere.

 

I agree with Blur and nat.(edit and all the ^^) it's probably pressure related. Not a rpm threshold problem. I know this has been said but I guess I will give it a shot at explaining how it works in theory. okay there is a pressure sensor in the (a/c)line that senses the amount of pressure in the line. this switch does two things 1(while this is NOT related to your problem I explain anyways) since the condensor(the piece in front of your radiator) needs airflow across to get rid of the heat.When you turn your A/C on the press sensor see's the rise in pressure and tells the pcm to turn the fans on, regarless of engine temp. 2 If there is not enough pressure(due to lack of freon) it will burn the compressor up if the AC is run. this it the other reason for the pressure switch if the switch senses not enough pressure so it shuts the compressor clutch off thats the click you hear.

I think whats happening with yours is you are line at the low line of operable pressure. I think with your cam your pressure sensor is seeing the same thing you see on the tach, which would be a rise and fall at idle and when it shuts the compressor off, once the pressure has built up/equalized in the lines it's just enough to turn it back on for a few seconds. And when you drive the car or bring the rpm up you are spinning the compressor faster ther for higher pressure at the sensor. So yes your underdrive could be hurting you, I don't have a under drive on my car when they make do the make the part that runs the A/C belt bigger to, I don't see why since you can just turn off the AC when you that little bit more. a easy way to tell might be, did you reuse your stock AC belt?

I would say take the car by and tell them you think the freon is low, so if it's low then that should solve the problem. if it's not then they won't be able to put any in and probably won't charge anything.

 

Now that I think about it, the pressure sensor is in the liquid line, before the orifice tube/expansion device, therefore it's almost like a high pressure switch. When the compressor kicks on, it goes from equilized pressure to HIGHER, I think it just makes sure that the pressure rises to a certain point, because it's definatly not going to drop. These cars do not have a low pressure switch at all.

The computer has a delay in the system which allows the compressor to get pumping before it checks to see if the pressure has increased enough in that line, which happens right around the time that yours kicks off.

This still means that you're probably low on freon though.

 

ok so just pick up a can of freon and where do i attach it to to charge the system??

also how do i know if i am overcharging? is that even possible?

as you might be able to tell im lost when it ocmes to the a\c ... so if someone can walk me thru this process i would be very grateful...

 

if you didn't have to change the size of your a/c belt with the under drive pully then the speed of the compressor didn't change idle due to pully. if it cycles on and off too fast at idle them the system is low. ( this will fry the clutch on the compressor) i wouldn't recommand doing it yourself if don't know anything about a/c and you don't have the proper tools. a good set of gages are about 100 bucks plus freon. most shops will service your a/c for around 100 bucks or less. if you still want to do it urself i can send you a pm with the basics