A/C temp

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Tnplumber

Tnplumber

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My car 72 Swinger 318 with factory A/c was converted to 134a by a A/c repair shop at some point. It has a slow leak somewhere in the A/c system. I refilled the system today until it began blowing cool air. The outside temp was 81 and very humid. Inside the car, with the A/C on it was blowing cool at between 55-58 degrees, while idling. It is equip with a two speed blower motor. When driving the car, the A/c doesn't seem to be cool enough, at least by modern car standards. Does that reading at the A/c vents sound like it is cooling properly??

Thanks

Scott
 
Should be about 10º cooler. Check the heater control valve in the heater hose to make sure it is closing all the way. If it isn't working properly it will keep the A/C from getting cold enough.

Chrysler A/C systems were designed to blow between 38-42º, but I don't remember what year cars that applies to.

Good Luck!

George
 
George R said:
Should be about 10º cooler. Check the heater control valve in the heater hose to make sure it is closing all the way. If it isn't working properly it will keep the A/C from getting cold enough.

Chrysler A/C systems were designed to blow between 38-42º, but I don't remember what year cars that applies to.

Good Luck!

George
Click to expand...

thanks George, I'll give that a look.

Scott
 
If its blows colder with less air flowing from your motor then your core might be clogged. I had the opposite happen with a heater core years ago. With the fan on the lowest speed the air would be hot but as it moved more air it god cooler and cooler. Took out the core and it was plugged up with all kinds of gunk. I wouldnt think it would happen with freon or 134a but I thought I would throw it out there.
 
Your system wasn't designed for 134a. To fully charge the system would bust hoses, etc... The only way to use 134a is to use less of it.
If you know what a fixed orifice tube is, yor system doesn't have that either.
Your system does however have a screen at the line in or high pressure side of your expansion valve similar to the one on a fixed orifice tube. This is a stack of cone shaped screens and should be removed , cleaned, and reinstalled. All you can do is move as much of the gas as possible in the older systems. It will never perform like a true 134a system or get as cold as r12 did.
 
Also your condensor was not made for r134. It will never cool as well as a modern parallel flow condensor.
 
When converting to R134, you should only fill the system to about 80% of the original R12 capacity. Hight side pressure should be about 2.2 times the air temperature in front of the condensor. As the outside humidity rises, the high side can be increased to about 2.5 times the temperature.

Another helpful thing is to hold the engine speed at your normal highway cruising rpm, 3000 rpm for 4cyl, about 2500 rpm for 6 cyl and some where near 2000 rpm for a v-8. at these speeds, check to see if the compressor short cycles (A/C fan on high, windows open, with warm outside air). If it does, you can add freon until the compressor stays on. Low side will be 20-30psi, high side at the 2.2 to 2.5 times the outside air temp in front of the condensor. Do not use the rpm method on a cool or cold day, like 60 degrees or less. At the lower temps, the A/C will short cycle due to the cooler air blowing across the evaporator.
 
I fought mine (72 Dart) for 3 yrs finally pulled everything out and bought an aftermarket and will be getting a sanden compressor with new hoses and all other parts, I want some COLD air.
 
The temp will be higher sitting and idling than when cruising. When sitting, the condensor gets hotter; when cruising, the air flow is cooling it.
 
134a sucks ive hated it for a long time ,you can stilll buy 12 a little costly bout 25 $ a can but the air is alot better colder at idle another scam the government sent forth on us freon put a hole in the ozone BULLS@@t. just like gas prices wall street scam the wall street convicts passing paper to jack up prices
 
dartman340ta said:
134a sucks ive hated it for a long time ,you can stilll buy 12 a little costly bout 25 $ a can but the air is alot better colder at idle another scam the government sent forth on us freon put a hole in the ozone BULLS@@t. just like gas prices wall street scam the wall street convicts passing paper to jack up prices
Click to expand...

totally agree
 
I went with the kit from Classic Auto Air, on a hot humid day, 38 degrees out of the far left vent, colder closer to the evaporator. What is really nice over the stock unit is the Sanden compressor, you don't even know it's engaged at idle and underhood is far cleaner than the stock system.
Don
 
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