Air conditioning intermittent on Buick Century

[papawhellie]

Not technically an A- body but 2000 century 3.1. Low mileage car and been having AC troubles since I bought it. I replaced computer because of the and transmission jumping acting weird and AC would work sometimes and not sometimes. My mechanic said the 5 volt reference signal was not always present so we put a computer in it. The tranny got better but still occasionally did the funky jerk like a misfire will cause in overdrive, a bucking shudder. I put some trans stuff BG ATC plus I bought at a yard sale in it and it seemed to cure the trans issue. Its a converter lockup product, I called their service rep before putting it in the car. Mechanic said maybe the clutch coil was weak on AC so I bought a new compressor and after installing it same problem exist. I left to go to the beach in St Augustine about 5.5 hours from West Georgia and the air was off and on several times for the first 3 hours, never running more than couple minutes, then compressor off. Started working on I-10 out of Jacksonville and pretty much worked the whole trip from there. Today 30 minute each way trip. Working going, no worky on the way back. This is an ongoing frustrating problem I have thrown $600-$700 plus at and no resolution. I have read the safety switch is located in the condenser but do not see one on Rockauto. There is a cut out relay AC Delco 13500114 and a control relay listed. Since the compressor was replaced and charged and same problem exist I do not think it is charge related. It is very cold and will run you out when working. I also think there is a higher speed or a secondary radiator fan involved when Ac is running on these models. Any help appreciated.

[tlc1976]

I’m not sure about the switches on the newer car. Is it possible the pressure is too high and it cuts itself out sometimes? I don’t know a lot about AC. It might also be the power steering pressure switch, I believe that cuts out the AC when steering at full lock to not kill the engine at idle. Or maybe it just revs it up a bit, not totally sure.

The original bucking in OD, more than likely sounds like an ignition problem. Happened to me with my Celebrity before and it was one or two bad spark plugs, cracked insulators. I had just changed them, but that was back when Walmart sold spark plugs. I learned my lesson. Another time was when I tried platinum style plugs in my 3.1. Didn’t like it. These engines only like old school copper AC plugs. Another time it wasn’t an all out buck but a miss, turned out to be a bad wire, discovered with a multimeter so I swapped on a spare I had. I think a bad coil or module caused a random buck in the past too. I’ve put over 500k on the 2.8/3.1 engines over the years. Anyway the reason you feel it in OD (or a limited time in 3rd) is because the converter is locked to the engine so you feel when things are off. When unlocked, a lot of issues are damped by the fluid connection in the trans.

[Pontiac6ksteawd]

The low pressure switchs on all 2000-06 GM products are known failure points. Its like a 10 dollar switch, and nothing special needed to replace it other than spin the old one off, spin the new one on, and done. Dont have to evac the system. It is usually sitting on the accumulator tank, or near the low pressure service port, wherever those are on this car.

[papawhellie]

In some reading I am leaning toward the switch. Seems it’s switching to the computer for it to supply a signal. Has 3 wires I think. I’m gonna order one and try it. The trans fix seemed to stop the bucking. Like tlc the older cars will let you know when they are skipping when they hit OD. Bucking like a bronco. Thanks P6 on the switch issues. Seems the post a-bodies have many issues the solid abodys don’t . Chip keys that fail, rotten abs cables, dash lights on, among others.

[papawhellie]

Turns out it was the inside control panel. The ac push button was losing connection or bad causing the clutch to disengage. It was a long costly battle to get this going. Stick with abodys their descendants are too complicated. Now my odometer has died, common problem bad resistors. Thanks