AC issues - 07 Mazda 6i

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Folks:

Going to the well again here - hoping someone can point me the right way.

AC performance is really suffering lately.

Compressor seems to be short cycling. The shop manual I have says the low pressure can go to about 14 psi (at about 77 degrees).

I know it varies by model, but this seems really low. The cheap low pressure gauge is all over the place - drops down to around 25psi and clicks off. (It spikes, then drops as it runs).

I'm assuming with proper set of gauges, I need to look at the high pressure and see if it's hitting the high pressure cutoff?

Thanks!
 
My 07 Mazda6 did the same thing a few years ago. I have a fulls set of gauges. Pressure was a little off as I recall but it's been so long, I don't remember precisely by how much. I charged the refrigerant with 3 oz and it improved. A few days later, I added another 2 oz and its been perfectly fine ever since.



Ray
 
14 PSI is way too low. An R134a system should be 35-50 PSI at that ambient temp, high side 170-210. Sounds like you're undercharged.
 
Ray
[/quote]
Originally Posted by Chris142
Radiator fans working? Suction line cold?


Fans run, and the large pipe to the firewall is cold.

Outside temps dropped into the mid 70's, and the vent temp is below 40.

But, it seems that after driving for a bit the short cycling starts, and there isn't enough cold air at idle (say at a light).

I'm going to pick up some gauges and see what the real readings are.
 
> after driving for a bit...

That is when you need to test. You can't tell anything looking at it when it is working.
 
Well - I hooked up gauges and must not have tightened the high pressure line enough. Pretty good sized leak happened at the gauge - gas and lubricant.

But - the good news is that the system must have been overcharged, because the temp dropped.

90 degree day today, and the temp at the vents was around 37.

So - I think I luck-boxed my way into a fix. And I have a fancy set of gauges when my home AC dies.
 
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