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Topic: Air Conditioning Question

in Forum: C3 Cooling and Heating Systems

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Air Conditioning Question (1/5)
6/2/13 7:14pm

corvettedave
Former Member
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Evansville`, IN - USA

Vette(s):
1972 Convertible, ontario orange, ps/pb/pw/air conditioning and 31,000 original miles.

Joined: 6/25/2007
Posts: 46

OK, let's see if this makes sense. In restoring my 72 convertible with factory air I bought all new components (condensor, POA, Evaporator, Compressor, Expansion Valve and dryer) except my hoses. They looked OK and I kept them.

I switched to the new 134A freon and charged the system. The system is holding a charge and the low side reads 30 psi and the high side reads 150 psi. The problem I'm having is the compressor is frosting up on the outside.

This can't be normal and I'm not getting any cool air. Any sugestions? Thanks David.

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Re: Air Conditioning Question (2/5)
6/2/13 8:26pm

Adams' Apple

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20129

What?! The compressor is frosting up?!? That's a first!
Not cooling at all, or just not cooling enough? 30 low and 150 high sounds like ya need a wee bit more freon to begin with. Sometimes, low refrigerant will cause the evaporator to freeze up...
Maybe Terry(my7T1) has more insight...

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Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

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Re: Air Conditioning Question (3/5)
6/3/13 2:03pm

corvette440hp

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Joined: 7/2/2006
Posts: 8205

At 32 degrees (evaporator) you would be seeing a 36.77 gage pressure. You need more refrigerant to get your pressure up. You also should charge with about a 2,000 rpm engine speed and your fan speed on high

|UPDATED|6/3/2013 11:03:39 AM (AZT)|/UPDATED|

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corvette440hp

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Re: Air Conditioning Question (4/5)
6/3/13 1:40pm

Adams' Apple

Yeeesh Larry...you'd need to be Neo in the Matrix to figure that out.....just looks like a bunch of 'puter code.... LOL

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Re: Air Conditioning Question (5/5)
6/3/13 1:55pm

my7t1

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Dorr, MI - USA

Vette(s):
71 Colonnade Hardtop Coupe Torch Red with black interior originally L48 built to push around 360hp

Joined: 8/21/2002
Posts: 2581

Ok, well having been in the AC business now for 40 years I have to say that I don't remember seeing this, but doesn't mean I haven't, but in my senile mind don't remember. Here's my take. You have a restriction. Why in the compressor is the question? First guess would be that its flooded with oil. Is the discharge line cold coming out of the compressor? Shouldn't be. When you charged it did you hook up at the suction line at the compressor, and put stuff in without the engine running? If so that could be why the compressor is flooded. Make sure you don't have too much oil in the system. When charging a system the first time make sure you turn the compressor around 15-20 time by hand to move the oil away from the compressor head. Actually depending on ambient temp. you pressure readings aren't bad. That's what kinda baffels me. Normally with a restriction your suction side will go down to ground zero.

Anyhoo, some stuff to check fer what its worth. Feel free to PM. Even leave phone number and I can give you a ring. "T"

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