G body AC compressor cycling question

[Mac442]

Converted my AC to 134a a week ago (85 442, 65000 miles).

New Delco compressor, orifice tube, accumulator. Changed the o rings.

Pulled and held vacuum. Recharged Freon and drove for about a week. AC blows very cold. Pressure is 35 low, 150 high side. Outside temp about 70. I noticed the compressor rarely cycles off at idle. Quick cycles while driving. Is this normal for this system? No icing or anything unusual.

 

[melloelky]

sometimes,not all the time you can adjust the clutch switch a little bit to change the cycle's,cycle..

 

[Ribbedroof]

How much refrigerant did you install?
What compressor (assuming R4)

 

[Mac442]

AC Delco 4849 R4 compressor. I put in about 80% of the original R12 amount (about 2.5 pounds).

 

[Ribbedroof]

I have converted 3, I charge to 85% of original system capacity. On an R4 system, that's 44 oz. On an A6 system, it'd be just under 3 lbs (47.6 oz). I should add that I have the luxury of using a dedicated refrigerant recovery/recycling machine, so no guessing as to how much came out of the small cans.

All worked well (too well, according to wife).

Short cycling is often a sign of an undercharged system.

Of course, temperature and humidity play a role in pressures/cooling effectiveness. As long as they aren't crazy high, I don't usually go nuts trying to hit a specific number on pressure.

I use an orifice tube for a 94 GM truck (originally spec'd for R134a) , I have never fooled with the variables so I can't speak to their effectiveness.

 

[Mac442]

sometimes,not all the time you can adjust the clutch switch a little bit to change the cycle's,cycle..

Is that the switch in the accumulator? Which way do it try to adjust it?

 

[oldsmobile joe]

Is it cold? Air vent outlet temp should be about 20-25 degrees below ambient. A/c compressors are more efficient, more cycle times, when rpms are raised. Also remember, cold temp is just one benefit of an a/c system, but dry air is an even better benefit.

 

[Mac442]

Is it cold? Air vent outlet temp should be about 20-25 degrees below ambient. A/c compressors are more efficient, more cycle times, when rpms are raised. Also remember, cold temp is just one benefit of an a/c system, but dry air is an even better benefit.

Yes, the air is cold. I’m wondering now if the pressure cycling switch is bad or could be adjusted.

 

[melloelky]

Is that the switch in the accumulator? Which way do it try to adjust it?

yep that switch that screws into the accumulator,if you pull the plug off between the two prongs there's a screw,i wasn't able to adjust mine but i have seen it done.i don't know if there's a difference between the r12 or the 134 switches.

 

[69hurstolds]

A post about adjusting that switch from last july...

AC Pressure Switch

Is there a GM pressure switch that will fit my 86' Regal that is compatible with 134A and uses the same 2 prong harness? Maybe off of a later model vehicle.

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