Looks like I need some help from one of you guys that knows the refrigeration stuff. AC's been getting weaker and weaker in the 1st Gen past couple years. This year it's about gone, so I figure time for a recharge, right? I replaced the dryer filter, pulled it down, seemed good, but when I go to recharge, it never gets above about 20lbs on the low side and maybe 150 tops on the high.

I've tried twice and seem to be getting nowhere. Compressor is running, seems like it starts to cool, but never gets to anywhere near where it should be. I'm no expert on the AC systems by any means, just know the basics, have gauges, etc.

Any ideas? I'm thinking maybe time for a new compressor, but no idea how to test it or know for sure.

TIA

 

Could be the compressor,but before we condemn it I need some more info.The pressures are not to far out.Have you got an accurate thermometer? We need to know what the center vent temp is,blower set to max,engine@1500rpm and the pressures while operating at these conditions.

 

Have you vac'd your system? I was having similar problems, after all said and done with my a/c. Vac'd it down, r134 seems to contaminate very easily.

 

Yea you need to give it a good vacum. You will clear the system and be able to tell if you have a leak or a clogged line filter.

 

Yes, that's what I meant when I said I "pulled it down." It never lost pressure, and seems to be sealed. It held 25Hg vacuum for a couple hours the first time I did it. I also ran it at 1100 rpm with the AC on high for over an hour the first time I was trying to recharge it. The 2nd time I let it go trying to charge for only about 20 minutes after I realized it wasn't doing anything. I have a big, high-volume fan hung off the grill guard blowing through the condenser to make sure it gets plenty of airflow during the charging process.

I left the gauges connected after I gave up yesterday to check them again this morning and it held pressure all night - 80lbs on the low side a 50 on the high. It doesn't seem to bleed across when I open both valves. I have a thermometer, but never even bothered checking temp at the outlets because it is obviously nowhere near what it should be - slightly cooler than ambient, at best.

I'm charging it with propane for now, because I'm not interested in wasting a fortune in refrigerant on troubleshooting and don't like the idea of a 134a conversion.

My un-educated guess still says compressor or possibly something clogged up in there somewhere...

 

How about the condenser? Is it clean with good air flow? It does seem like compressor issue, but check the simple stuff first, right?

 

If your pressures aren't equalizing, you have a restricted orfice tube,or a TXV(thermostatic expansion valve) malfunctioning.

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If you apply pressure to the highside(discharge or liquid)line only,you should see a rapid rise in pressure on the lowside (suction) gauge,until the reaching the point of equalization. This should happen within a couple of minutes,generally faster.

 

I did not know why, but it seemed odd the pressures did not equalize after shutdown. I'm going to try that and see what happens. Would an expansion valve problem jibe with the low pressures I was seeing while trying to charge it?

 

I agree with only1. the expansion valve is probably sticking. If your pressures aren't equalized then something is sticking. Also the pressures should coincide with your ambient air temp.

 

Yes,TXV's can partially restrict causing problems such as what your seeing. I also noticed that your using Propane as an alternate for R-12 for the moment. Be aware of this....If it's not a purified propane specifically for refrigerant,it will contain moisture.All it takes is for a spot of moisture to pass thru the orfice in the TXV and freeze,creating a partial to full restriction. This is something to consider,but it will not cause a system not to equalize,given enough time for the ice pellet to thaw in the TXV.