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Discussion Starter #1
My '03 Sonoma A/C will blow fine and strong when it's first turned on but after a while (time varies, could be 5 min or 25 min) the air comes out very weak no matter the fan speed and I have to turn the A/C off to let it sort of reset before I turn it on again and it works normal for a period of time. On long drives, I repeat this process often. I also notice that sometimes when I turn on the A/C I hear a muffled "thump" from the accumulator. It is also noticeable when I turn the A/C on because the engine runs different and I can hear/feel that from the Compressor area. The clutch spins silent though when I checked the other day.

I swapped out the A/C clutch switch recently too and there was noticeable leakage from the accumulator at that point. It seems to have stopped since replacing the clutch switch and o-ring. But the other issues listed above are still persisting... Any ideas?
 

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Check that your vacuum lines aren't brittle, mine were brittle and torn apart and after replacing them the AC blew like it was meant to
 

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It sounds like you have a compressor that has gone out becasue the seals are worn out. Here is a guide to show you how to change the compressor out and vacuum down and recharge the system.

 

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Discussion Starter #4
Thanks. I was hoping it wasn’t the compressor, but all hoses look fine (no leaking, but frayed and worn). I’ll have to replace those hoses soon. Now I’ll add this to the “to do” list.
 

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The compressor has nothing to do with the volume of air coming out of the vents.
Is the water draining out of the evaporator case? Do you see any lines freezing up? The evaporator could be freezing up and blocking the air flow.
 

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4 or 6 cylinder? (controls /compressor are different)
 

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Discussion Starter #7
It’s a 4.3. I haven’t run the a/c in a while and haven’t checked the evaporation case. Likely won’t need a/c until next year. I’ll try to remember for next year
 

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94 4x4,01 Blazer
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your a/c kicks on when you run your defroster- its a year round thing- the thump is your temp selector door open/closing- low air after time is usually a sign of a blower motor getting hot/binding up- red neck fix- small drill bit with a bit of real grease to attract metal- drill tiny hole in the nipple on back of blower motor- using a 3-1 oil dripper- oil the bearing- or just replace the whole motor. additional check - pull the blower out and check/clean the squirrel cage and the area it goes into.and check your intake (under the cowl) for debris.
 

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Discussion Starter #9
your a/c kicks on when you run your defroster- its a year round thing- the thump is your temp selector door open/closing- low air after time is usually a sign of a blower motor getting hot/binding up- red neck fix- small drill bit with a bit of real grease to attract metal- drill tiny hole in the nipple on back of blower motor- using a 3-1 oil dripper- oil the bearing- or just replace the whole motor. additional check - pull the blower out and check/clean the squirrel cage and the area it goes into.and check your intake (under the cowl) for debris.
Thanks for the tips. With that info, I’ll probably just replace the blower motor. The odd thing is the air flow isn’t reduced when the defroster is on. Could it be something other than the blower motor?

Regarding the temp selector; should that be replaced? I’ve never heard the thump in any of me vehicles before.
 

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94 4x4,01 Blazer
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ok- that little tidbit told me more- chevymec was on the right path- your cooling coil is freezing up- think the gridwork in a freezer full of frost- your drain is plugged and or you got crap down in there- pull blower motor out -get a can of a/c coil cleaner- and apply to the cooling coil- and attempt to clear that drain- runs toward passenger side door jamb
 

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Look to the drivers side of the blower for leaves and nests stuck up in there while you have motor out. That can get real clogged up and restrict air flow. Might have to bend a piece of heavy wire into a hook to reach in far enough to get it all out if it's bad.
 

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Look to the drivers side of the blower for leaves and nests stuck up in there while you have motor out. That can get real clogged up and restrict air flow. Might have to bend a piece of heavy wire into a hook to reach in far enough to get it all out if it's bad.
wet vac,heater hose and duct tape are your friends when trying to clean an evap case.
 
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