Did I screw up my A/C system?

[Maverick1701]

so I checked my low pressure and it was around 35psi so I added most of the can and it upped it to around 37-40ish.
(if should be 45psi)

I was driving around w/out much of a change....that is until I switched my a/c over to the vent mode and I felt the engine work a little.
I checked pressure on the low side again and it had spiked well into the red zone on the gauge...once I switched back to max a/c it was back down to 37
Is this normal?!?!?!

on max it still blows cool air (about the same temp as before) and the same psi

When i click it over to vent my pressure climbs to 140psi where it plateaus and remains at 140psi

Any ideas?

[metallitera]

when u say vent, do u mean A/C OFF, or OUTSIDE air with A/C ON as opposed to re circ inside air?

when A/C is OFF i believe the pressure equalizes throughout the system, thats why you only go off readings while system is ON.

someone correct me if im wrong.

[elibenson]

Correct! When the compressor is not running (vent mode or off), the high and low sides equalize. It will end up being about 140-180ish on both sides. As soon as you click the compressor on, it will drop down on the low side, and up on the high side.

About the running pressure, 37-40 is a little low still. R134a is picky about the pressure it runs at. A little high or a little low will both be less efficient than having the exact amount for your particular application.

45 psi on the low side is good if your ambient temperature is 80 to 85 degrees. If you are in South Texas at 104 ambient temp, the low side will be 60ish.. There are charts that detail what ambient temp and what pressures are normal.

[Maverick1701]

Originally Posted by elibenson

Correct! When the compressor is not running (vent mode or off), the high and low sides equalize. It will end up being about 140-180ish on both sides. As soon as you click the compressor on, it will drop down on the low side, and up on the high side.

About the running pressure, 37-40 is a little low still. R134a is picky about the pressure it runs at. A little high or a little low will both be less efficient than having the exact amount for your particular application.

45 psi on the low side is good if your ambient temperature is 80 to 85 degrees. If you are in South Texas at 104 ambient temp, the low side will be 60ish.. There are charts that detail what ambient temp and what pressures are normal.

PHEW! That is GREAT news.... I saw that needle going up and up and all I could hear was $$$$$$$$$

As long as it is doing what it should....that is good news

The info on the can says for 100*-110* (south-east tx) the psi should be 55 but but I am still at 37

[Jarrod B]

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[elibenson]

I threw out some numbers from memory, so they may not be exactly on the money..

Sounds like you need another can of refrigerant..

[ghostang93]

That next can of refrig you throw in, you might grab one that has the dye in it. That ways you can use a black light to check for leaks a bit better. Don't know who needs the A/C more, you in the high heat of TX or me with the high humidity of FL, either way its sucks without it.

Dave D