A/C pressure readings? 96 Lexus LS 450


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Old 03-15-08, 08:47 PM
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A/C pressure readings? 96 Lexus LS 450

Car wasn't cooling right... Guages read 20psi low side and 215psi high at 75F. Put in three cans of 134a low side went to 28psi and high to 275 at 75F. System didn't seem to suck the freon like I'm used to. I was wondering what the system should read? I was thinking 35-45 on the low and 150-170 on high. Kind of conerned since the high side is so high and the low doesn't seem to be rising much. Inside air temp was at 40F now with the system on max and the windows up.
Thanks...
 
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Old 03-19-08, 08:05 PM
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Originally Posted by 65GTO
Car wasn't cooling right... Guages read 20psi low side and 215psi high at 75F. Put in three cans of 134a low side went to 28psi and high to 275 at 75F. System didn't seem to suck the freon like I'm used to. I was wondering what the system should read? I was thinking 35-45 on the low and 150-170 on high. Kind of conerned since the high side is so high and the low doesn't seem to be rising much. Inside air temp was at 40F now with the system on max and the windows up.
Thanks...
65,
The fact that you were already getting 215psig on the high side at 75F ambient should have been a red flag to not add any refrigerant! At that temp, using the (2.5 x ambient) formula, your ballpark high side should be about 190psig to 200psig, so you were right in there before adding the three cans.

Actually your original numbers looked pretty good before you added the refrigerant. It's possible the heater core is adding heat and that's why your not cooling properly.

There's a lot more to check in MVAC than just the refrigerant level! Right now by adding three cans you're probably WAY overcharged!

At this point if I were you, I would recover the charge, pull a vacuum, and then recharge by weight according to the A/C sticker on car. At least that way you'll know you've got the charge right and if it's still not cooling properly, you can start looking for other problems..........

Good luck,
Phil
 
 

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