1998 Blazer, 4dr., 2WD, automatic trans., 4.3L, original owner, 130K miles. No A/C problems since new compressor, dryer, orifice tube & hi-pres. switch on 5/16/11 at 98K miles. Checked freon after sitting all-night; 100PSI at low-side with system-off and 35PSI with system running at MAX Cooling settings at 1000RPM with shop fan blowing on condenser/radiator in Neutral in garage. Indicating 50F air at outlets with 95F OAT. Ran it that way three times (30, 45 & 60 minutes) without experiencing any compressor shutdowns. However, if I drive normally on the street, compressor quits after two miles, ten minutes max. Outlet air temps remain at 50F and do not fluctuate until compressor quits. Compressor will NOT re-engage until everything cools down overnight. FYI, I have 1997 GM S/T Truck Service Manual and need confirmation that my 1998 system and components are the same before digging deeper into my old Blazer. NOTE: Checked for DTC codes with my scanner and found ZERO! Comments, questions, suggestions?

 

If nothing was added or replaced since the new compressor was put in, #1 I'm going suggest checking for a .30 inch air gap at the compressor clutch. #2 apply 12v directly to compressor clutch to check coil operation. You don't say what your high side pressures are.

 

I have had same trouble 2x in last 6 years. Both times excess oil in the low side switch on the accumulator was the issue. Just screw yours off and shake it on a paper towel (you won't lose freon because of valve). If you get oil out of it, then replace it. You might want to replace it anyways - It's cheap and 60 seconds to change.

 

Kv, thanks for the quick reply. Nothing touched since the 2011 repair. Will look at the issues you specified. No high-side pressures due to bad gauge.

LesM, Glad to know someone besides me has experienced this same situation. Will let you know what I find. Thanks!

 

As mentioned, the addition of high side pressures would be best.

35 psi low side with 95F ambient is too low, you may be low on gas. You can confirm by jumping the low side switch connector temporarily after it quits to see if it starts. The recommendation to jumper the compressor will take the low side switch wiring and controls out of the equation but not the high side switch depending on where you jumper. When it quits does the compressor stop rotating? Is the clutch also disengaged?


George

 

Shouis be more like 43 psi low side. I think mine, when I rebuilt it, was 42- 45 F with about 85-90 outside.

Nothing in your post indicated following correct charging procedure so it could be low on refrigerant. Clean, flush, evacuate, oil and charge by weight.

Check that the Schrader valve caps are clean and tight also...they can slowly bleed refrigerant off.

Look for oil stains around the front of the compressor and at line connections if its low on gas.

 

Thanks for all the posts/input/suggestions! Have a damaged/sticking Schrader valve in the Low Side Service Port. Am stopping my tinkering and will get that repaired professionally and see if they can identify any other issues while they have it. Will update my thread with results.

 

In my experience, that's usually caused by cranking the gauge connector down too hard. I usually turn the **** until pressure registers on the gauge, and then another half turn or so. You don't want to turn it until it stops. Just for future reference.

 

I promised you an update and here it is. In preparation to have the low-side service port repaired/replaced, I made one final inspection of the system to the best of my limited abilities with the help of my 1997 GM S/T Truck Service Manual. While looking for traces of oil in and/or around the "pressure cycling switch" on the accumulator, I removed the electrical connector but NOT the switch. Although I could not identify any oil residue, I cleaned the switch and connector with WD-40 then re-installed the connector. After numerous starts/stops/miles since performing that insignificant bit of service, the A/C has worked perfectly! Thanks for your help. I'm certain I will be back looking for help again.