My A/C Compressor is kicking on and off while at idle when the A/C is turned on? Not enough Freon? It's a Brand New Compressor...

 

It's supposed to - they dont run constantly.

 

Sounds like the symtom of a low charge.

JamesC

 

I'm confused... I don't recall the A/C Compressor kicking on and off on any other car while it's at idle???

 

They do, especially newer cars. In the old days, they stayed either on or off, but in the 1980's they started cycling them. Listen to any new car with A/C on, it cycles on and off, about every 10 seconds or so.

Like mentioned, if it's cycling on/off more than that, could be a low charge and needs a recharge. But they do cycle on/off constantly (at least at idle).

 

Check your vent temps... If there around 42 degrees or 20 cooler than outside temps your doing fine. They cycle basied on evaporator core temp. If they ran all the time they would just turn the evap core into an ice block and you wouldnt get any air.

 

I knew there was agood reason why they cycled, just couldn't think of it!

 

Shoot me a number for the ideal freon pressure on the low side...

 

In March, I would expect the compressor to cycle on and off at idle. Even after only 30 seconds of the car running. Maybe less.

The outside temp is so low that the condenser can send extreme amounts of heat to the ambient. As such, this brings the low side pressure down to the low pressure cycle point.

The real question is how does the inside of the car feel? If it's cool, than everything should be good. If it's not cool, then it's not running for long enough (short cycling)

 

So it's normal for it to switch on and off huh? It just doesn't seem right... When I'm at a light the whole car kind of moves when the compressor kicks on and off due to the change in RPM's.

 

There are 2 types of AC systems. One called an orifice tube cycling clutch system which our cars have and many others. The other is called an thermal expansion valve system or TXV which are in alot of cars also. You will see the TXV system in just about every old car out there before 1980. The OTCCS cycles the compressor to maintain the evaporater core temp. If it ran all the time, it will eventually iceberg the evap. core. Outside temp and blower motor speed has alot to due with how this system performs. The TXV system will run the compressor all the time as the expansion valve in the system creates and regulates the high to low pressure in the system. In the OTCCS, the orifice tube creates the high to low pressure but cant regulate it. That why the compressor cycles via the low pressure cut-out switch on the accumulator. Thirdgens are designed to cycle the AC compressor. Compressor on and off times along with blower motor speed and outside temp is an indicator on how the system is performing.

 

I have a question about my AC, Well the AC didn't work, had it charged worked great! Well the last few days, it has cycling a lot and I smelled a burning wire smell last few days but no one else did. Today when I drove car AC didn't work right. So I checked the top wire connector that clips on the compressor and it looked a little fried inside the connector. Can the connectors go bad? Or should I be checking something else? Thanks in advance for any help!

 

bump really would like to know! what could be problem if wiring connector to AC is burnt looking?

 

Connectors can go bad with time. They start to dry out and get brittle and the wires start to get brittle too. When this happens, it can start to create a bad connection. If you suspect a bad connection with the connector, try doing a wiggle test to the connector when the system is operating. Also inspect the wires for damage or breakage.

 

If its kicking on and off neurotically then its low charge and the kicking on and off can hurt the clutch and if that is shorting then it can damage the wiring. When I converted mine to 134 it was doing that till I got the pressure right but I also had a 95 saturn that burned out the AC wires from the clutch going.

 

Mine "groans" pretty loud when at idle. Vibrates the whole car. Is that normal as well? Seems to cool fine.

 

the groaning could be bad bearings in the ac clutch

 

Where is the clutch on the AC located? If you have picture's would be great!
If replacing the clutch, do you have to evac all Freon?
Thank you

 

the clutch is the whole assembly that the belt goes around and you can get a replacement clutch from your auto parts store but I don't think you have to evac the system to swap it

 

Fixed...

Low Charge I would presume, Had it filled with 2.5 LBS of Freon. Finally decided to stop trying to self diagnose it with the Freon Cans from AutoZone... What a waste of money, Live and Learn.