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My A/C blows constant but i notice when it is hot out it seems not to be blowing very cold. When the sun goes down it feels really cold. I was told to re-charge with 134a refrigerant which i did. Someone said i might of had to use r-12, im not sure. What could this be please help. I live in Florida so its hot. Thank YOU
 

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You might need to replace the condenser, but I'm not sure. All of my bimmers had working AC, but I have had other cars which the AC was broken, and I ended up never fixing it.
 

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unless you are experienced with ac systems, i would suggest taking it to the experts. however, i can give you some advice.

1-turn the system on, and check the operation of the compressor clutch, and auxillary fan.
2-if you 'charged' the system, you would need to have r134a ports (can't get r12 without a license).
3-if you hooked guages to the ports (blue is low, red is high, can't get them mixed up) they should read ambient temp (+/- a few degrees F). once you start the system, the low side should drop and average 30 psi, and the high side should be about 100-120 F above ambient temp. however, it shouldn't climb above 250. run some cold water over the condenser (simulates airflow) to keep high temps down.
4-vent temp with max cooling setting should be about 38-45 F, low vent speed.

average cycling on/off for the compressor is about 8 times per minute max. faster than this usually indicates a low volume in the system. how low will vary depending on design of the system, but usually about 16oz or so. maybe even more. the only way to know for sure how much refrigerant is in a system is to fully evacuate and recharge with the proper amount of refrigerant. (for instance, a single 12oz can, full 30lb canister, and 1/2 full 30lb canister will all read the same pressure at rest, approximately ambient temp. a system that is full, 1/2 full, and about 1/4 full would all read close to amient temps at rest, but will have different cycling times and vent temps.)

one of the most common issues i have seen with diy'ers and r134a ac systems is overcharging. very easy to do, and the most common sign is higher high side reading and
low side reading, and of course, higher vent temps. rule of thumb is about 10 points higher vent than the average low side reading. (if the low side is cycling from 20-40, the avg = 30, add 10, and the vent temp should be about 40)

if the cycling is ok, and the pressures are within range, and cooling fans are operating properly, but the vent temps are higher, you may be looking at a possible blend door or airbox malfunction, and that is a different sort of diagnosis.

hope this helps. pm me if you have any other questions, or need clarification on this.

drivinfaster
 

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What about a high reading on low pressure side?

Im not sure if it the crappy $10 gauge/fill hose I have or some other problem, But when I put it on my low side, with the system running, I recall getting a ~70 PSI reading. I checked it last fall and decided to give up on it. The system is not as cool as it could be, but still works fine. Does this mean the previous owner has overfilled? A mechanic friend of mine said that the low side sometimes shows high readings on those cheap gauges until you get the right amount of freon in the system. Ever heard of that one?
 

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My A/C blows constant but i notice when it is hot out it seems not to be blowing very cold. When the sun goes down it feels really cold. I was told to re-charge with 134a refrigerant which i did. Someone said i might of had to use r-12, im not sure. What could this be please help. I live in Florida so its hot. Thank YOU
I have the same problem...When the sun goes down my A/C blows very cold. So cold that I can actually see frost on my windshield. However, when it is very hot outside and the sun is out its not as cold, but it still blows fine..Wonder what it could be? Anyone else experience this that has a solution?
 
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