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A/C line freezing


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#1 blackbird2001

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Posted 09 July 2012 - 05:31 PM

I've been having a problem with my a/c after driving for an hour, the air coming from the vents is very light even at max blower speed. After the car is off for a while, the a/c works fine, cold and strong as always. It happened today and I looked under the hood and there was frost on the a/c lines. I decided to run a blow dryer to defrost it and sure enough, the air was coming out the vents like normal. What is causing this? I have to fix it cause I'm taking 2 long drives this month and can't be without air on these trips! Thanks in advance. It's an 01 V6

#2 Boyer

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Posted 10 July 2012 - 09:17 AM

Usually if the evaporator is iced over, you're either too low of a charge or there is too much of a blockage at the orifice tube.

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#3 djfirebird93

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Posted 10 July 2012 - 10:12 PM

ok, i'm so confused here as to what the "evaporator" is. I thought the evaporator is the thing by the firewall, the thing that the orifice tube goes into, and the silver thing that sits next to the battery and what holds the low pressure fitting is called the Receiver/Dryer, or so I thought. The silver thing on mine always has condensation on it, but is never frozen over.
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#4 Boyer

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Posted 11 July 2012 - 12:09 PM

ok, i'm so confused here as to what the "evaporator" is. I thought the evaporator is the thing by the firewall, the thing that the orifice tube goes into, and the silver thing that sits next to the battery and what holds the low pressure fitting is called the Receiver/Dryer, or so I thought. The silver thing on mine always has condensation on it, but is never frozen over.


You're right, but it's very possible that the evaporator can ice over, restricting the cold air flow, it'll still be cold, just not much air flow.

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#5 GaryDoug

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Posted 11 July 2012 - 12:45 PM

I have heard that the Variable Displacement valve in the compressor can be defective causing the system to "over-cool" and ice over. I don't have much knowledge here, just know that the later Firebirds (96-02) have the VDOT style compressors to control refrigerant flow instead of using clutch-cycling (CCOT)
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#6 Knightfire83

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Posted 14 July 2012 - 01:23 AM

Seems the thing to do would be to put a gauge on the low side and see where your pressure is at. Probably a bit low.

#7 blackbird2001

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Posted 14 July 2012 - 09:12 AM

Pressure and refrigerant are normal. Plenty of water drainage so there seems to be no blockage. Someone suggested the inline filter might have blockage? Anyone know where that is so I can replace it? Is the filter the same as the orifice tube?

Edited by blackbird2001, 14 July 2012 - 09:34 AM.


#8 djfirebird93

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Posted 14 July 2012 - 12:54 PM

Yes, the filter is the orifice tube.
My bird is a working progress. New Marshall engine-forged pistons, upgraded rockers and stronger rods/bearings. Rebuilt transmission. New LSD. I wish money grew on trees :)




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