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  #1  
Old 05-04-2012, 03:02 PM
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Default 2000 Bravada A/C issue 100lbs Low port

Bravada's had some issues with the a/c coming on for a min and then going off. Now that it is my only available car it's time to get it fixed. Today it was working fine on the way to work. After work it decided to blow hot air. I looked under the hood and noticed the clutch not engaging. While the a/c was "running" the low pressure port said 100lbs(in the red warning). Now did it read this because of the clutch not being engaged or is there possibly some type of blockage.

Last edited by cbierniat; 05-05-2012 at 09:16 AM. Reason: No response
  #2  
Old 05-05-2012, 12:27 PM
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oomph? usually clutch cycling is low charge, can be high too... 100 psi? if thats the low side reading with the compressor clutch off, and engine is hot, that is about right. if that with the comp running u r way way overcharged or have a blockage which i doubt. sounds like your low to me, low side system on should be between 30 to 50 depending on ambiant air temp. thats not a good way to charge by btw, only acurate way is to weigh in gas from system empty in a vacumne. now if its really that high, other than a blockage prob orfice tube? unlikley cause if that much debis in system then comp is blown up by then. only other things that cause high pressure when running is low airflow, either evaporator coil or condenser, plugged w crap, fan clutch just free spinning etc. a/c function is all about air flow, it just takes heat from 1 radiator and moves it to another.
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Old 05-05-2012, 12:29 PM
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sorry, 30-50 low side is system on high, clutch engauged. and i know i cant spell worth a damn lol
  #4  
Old 05-05-2012, 04:15 PM
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If I understand correctly, your AC was short cycling, now it doesnt come on at all.

The pressure at low side port with compressor off is a function of temperature only
assuming there is any refrigerant in the system at all. When it was short cycling pressure was probably dropping rapidly under 40 or so psi.
You read 100 psi static pressure so you are right the compressor clutch should be engaging.
First check the AC clutch fuse.
then
Remove the connector from the low side cycling sw on the accumulator and jump the wires in that connector, engine running - ac on. If clutch engages, then you have a bad switch. It can be easily replaced without losing refrigerant, just unscrews.
If nothing happens, disconnect the connector at clutch and ohm out clutch coil. Should read between 3 and 7 ohm or so.. lower means coil is shorted internally.
Fuse will blow when that happens.
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Last edited by pettyfog; 05-05-2012 at 04:25 PM.
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Old 05-05-2012, 07:37 PM
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Compressor kicked on so I jumped and hooked up the gauge... it read 17lbs on the low side.. The accumulator was ice cold and sweating..

I obviously need to add freon I will try and see what happens.
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Old 05-05-2012, 08:22 PM
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STOP!

Do not add freon till you replace that switch. If the accumularor started sweating quickly, th eswitch is probably bad, not the charge

And yes... you trust a NEW switch before you trust a gauge that cost a dollar to make.
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Last edited by pettyfog; 05-05-2012 at 08:58 PM.
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Old 05-05-2012, 09:08 PM
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So replace the low pressure switch and then retest the pressure? Then if needed add to 35lbs correct?
  #8  
Old 05-05-2012, 09:29 PM
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I told you.. DO NOT trust those CHEAP gauges.
Go by the new switch. Turn ac and blower on high, max cool. Vent temp should be 55-58 degrees. Once the temp is 70 deg on passenger floor well, compressor may cycle.
Low side line should be cool {refrigerator temp.. about 40 deg} to the compressor.
I have a good set of HVAC gauges and I go by performance, not pressure. I use gauges to troubleshoot. And to set it up if system has been opened.
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Old 05-09-2012, 10:03 PM
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Update...

First of all I would like to thank PettyFog for telling me not to trust my old cheap gauge. I remembered that I had found a way newer one over the winter. I retested it and found it was at 30psi and not 17 (same temp high 60s). I then replaced the low pressure switch suggested by Pettyfog. It has seemed to cure the problem and the a/c compressor stays on w/o shutting down anymore.

PETTYFOG I <3 You
Old 05-09-2012, 10:03 PM
 
 
 
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10, 1995, 2000, ac, air, blazer, bravada, bravda, chevy, conditioner, cycling, frequent, fuse, min, stops, works


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