a/c not cooling
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Cruising
Joined: Jan 2016
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a/c not cooling
my a/c is not cooling. i replaced the accumulator, vacuumed the system to 29.5. waited for 3 hours, no leaks. also converted to r134, new o'rings. added freon and the compressor came on. put in 2.25#'s and suddenly the gauges became hot and the pressures were 110 on low side and 450 on highside. the compressor kept cycling but the air in the car was still hot. i am not sure of the problem. can u help?
Thread Starter
Cruising
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Safety Car
Joined: Sep 2004
Posts: 3,953
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From: Mission Viejo CA
It looks like your high side safety switch, which normally would never actuate, is cutting off your compressor. This safety switch opens the compressor circuit at about 400 psi! Your low side should be less than 80 psi, even with the car parked, engine off and cool.
Race Director
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From: Lansing MI
Melting Slicks
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From: Palmdale CA
Wow! this is gnarly.. 
I hope your at least wearing safety glass's
R134a should run at about 30-35 psi low side. <28 psi and the Evap will ice up, so you need to monitor this while charging.
The rule of thumb for the high side pressure is Ambient x [2] + [10-20%]
example; 100° day = 240psi at the High side (Condenser) so you also need to monitor this as well!
The above pressure's will only work if there is adequate air flow across the Condenser, and it is properly sized for R134. The rule of thumb is to charge at 70% of the factory R12 specification, and then slowly add about one ounce at a time until the center vent discharge temperature reach's it's coldest point, should be somewhere about 80% of the factory spec.
I don't know what the safety relief valve is set for on the back of the compressor, but I have a hunch you about set it off.. this would have been real messy..
I hope your at least wearing safety glass's
R134a should run at about 30-35 psi low side. <28 psi and the Evap will ice up, so you need to monitor this while charging.
The rule of thumb for the high side pressure is Ambient x [2] + [10-20%]
example; 100° day = 240psi at the High side (Condenser) so you also need to monitor this as well!
The above pressure's will only work if there is adequate air flow across the Condenser, and it is properly sized for R134. The rule of thumb is to charge at 70% of the factory R12 specification, and then slowly add about one ounce at a time until the center vent discharge temperature reach's it's coldest point, should be somewhere about 80% of the factory spec.
I don't know what the safety relief valve is set for on the back of the compressor, but I have a hunch you about set it off.. this would have been real messy..
Thread Starter
Cruising
Joined: Jan 2016
Posts: 12
Likes: 0
a/c not cooling
i'm lost n the terminology of high side safety switch. any other name?
Thread Starter
Cruising
Joined: Jan 2016
Posts: 12
Likes: 0
a/c not cooling
Wow! this is gnarly..
I hope your at least wearing safety glass's
R134a should run at about 30-35 psi low side. <28 psi and the Evap will ice up, so you need to monitor this while charging.
The rule of thumb for the high side pressure is Ambient x [2] + [10-20%]
example; 100° day = 240psi at the High side (Condenser) so you also need to monitor this as well!
The above pressure's will only work if there is adequate air flow across the Condenser, and it is properly sized for R134. The rule of thumb is to charge at 70% of the factory R12 specification, and then slowly add about one ounce at a time until the center vent discharge temperature reach's it's coldest point, should be somewhere about 80% of the factory spec.
I don't know what the safety relief valve is set for on the back of the compressor, but I have a hunch you about set it off.. this would have been real messy..
I hope your at least wearing safety glass's
R134a should run at about 30-35 psi low side. <28 psi and the Evap will ice up, so you need to monitor this while charging.
The rule of thumb for the high side pressure is Ambient x [2] + [10-20%]
example; 100° day = 240psi at the High side (Condenser) so you also need to monitor this as well!
The above pressure's will only work if there is adequate air flow across the Condenser, and it is properly sized for R134. The rule of thumb is to charge at 70% of the factory R12 specification, and then slowly add about one ounce at a time until the center vent discharge temperature reach's it's coldest point, should be somewhere about 80% of the factory spec.
I don't know what the safety relief valve is set for on the back of the compressor, but I have a hunch you about set it off.. this would have been real messy..
Race Director
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From: Lansing MI
Safety Car
Joined: Sep 2004
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From: Mission Viejo CA
Instructor
Joined: Jul 2007
Posts: 130
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From: Goshen IN
When your talking "cooling fan', is that the small shrouded fan(30amp fuse) down in front of the engine clutch cooling fan?
Last edited by Rmodeler; Jul 15, 2016 at 07:58 PM. Reason: clarification