Hey all,

I have a 2003 Century, 3.1, and the A/C compressor does not cycle as my other GM vehicles do. The A/C blows ice cold no matter what the temp is out side. I did few things already. Evacuated the system and recharged it with the specified (by weight) R134a. Hooked up the gauges and at 100 ambient, on max, high fan speed, it blow ice cold, 45psi on the low side and 200 on the high side. I can't find the required PSI data anywhere, but notice the literature for R134a shows i am at the low side of the expected PSI. I set the fan on in the max setting and normally this results in cycling. Any ideas?

 

I suspect your scale is off because it sounds like the system is slightly overcharged.
If you bring the RPM up to around 2000 RPM the low side should go down to near 30-35 psi. Eventually it should go down to 28 where it should cycle and the mag clutch should release. Of course the cycling switch could be off spec. And,,, I could be wrong too !

 

Thank you, this is what i am looking for. I have used two sets of gauges, both read the same. I suspected i was overcharged.

 

What you can do is to "recover", I can't say release to the atmosphere, some of the refrigerant and with the engine at approx 1500-2000 RPM continue "recovering" until the low side press gets to approx 28 and the clutch releases and that should get you in the ballpark. If it cycles too often , add a little. There is an approx # of cycles per minute at that RPM, but it differs with ambient temp.

 

What is weird is my buddy has the same exact car. he has never had the AC serviced and his doesn't cycle either. We hung the gauges (new ones) and he was showing 35 on low and 180 on the high at idle. We brought it up to 1500 rpm and it went to 28/200 respectively, with no cycling either. I am totally confused.

 

The purpose of having the system cycle is to prevent evaporator freeze up and of course reduce some drag on the engine. This affected the vehicle's mileage. If the checks were made when the ambient temp was quite high the refrigerant expands and pressures are a little higher. You can try both settings and see what works best for you. If performance isn't what you had in the past , you can always add a little.

 

Hi Capt,this will be my first post,and Im doing AC for 27 yrs, with 100 ambient,combined with the heat gain from the glass,i doubt your system would have the chance to cycle.Are you taking your pressure readings with the car at 1500rpms like Hanky said?You have to or else your readings arent accurate.If you charged by weight to spec,how is it you think your overcharged?Its more likely you have air in the system.Did you purge your hoses of air before opening them up to the system?

 

Was about to ask the purge part too. The gages are for R134a?