I have Honda Accord 2002 SE. Today my a/c was blowing not as cold as it used to be, so I checked refrigerant level. It was high in red and I decided to discharge it pushing on the high end port. Somehow I emptied it down to zero pressure, so I filled it again with refrigerant to normal pressure for this weather...And this made it worse, ac started to blow heat! (sounds like magic, but true) Eventually, it gets back to outside temperature and gauge reads zero again.

So why when my car has refrigerant it blows hot air? Did I break the physics of the universe?!

  • Also, question is that normal for high pressure port to blow air? Like pshhh Jun 25, 2016 at 4:44
  • 1
    do you mean the valve is leaking?
    – Ben
    Jun 25, 2016 at 12:27

2 Answers 2


No, you didn't break the laws of physics. In fact, you confirmed them. If you "refilled" the refrigerant in the system from cans without pulling a very strong vacuum, you still have regular air in the system, and it will not cool. You are also subjecting the internal components to moisture, and that's bad.

AC refrigeration emptying and refilling is not a do-it-yourself project. You need special equipment to refill the system properly (full vacuum for 24 hours followed by pressurized refilling and lubricant). The good professional mechanics will check for leaks and fix them.

Topping off some R-134 occasionally (no more than once a year) is okay, but more often means you need help from someone with experience.


If the "gauge gets back to zero" at any time, on either the low or high side, you have a leak. Perhaps a very large one. The gauge should never read zero, unless ALL the refrgerant has leaked out.

When you discharged the high side, are you certain the schrader valve core in the port re-seated? Or that debris hasn't ended up under the conical seal, allowing a huge leak?

(This happens to be the common spot for a great number of A/C system leaks.)

No, it's not normal for the high pressure port to blow "air", refrigerant, or make any kind of pshhh noise.

There is a special tool, not unlike the ones used on tire valve stems, for removing the schrader core from the port(s) and replacing them. Both the tool and the new valve core are very inexpensive.

Also, sometimes they just get loose, and need to be re-tightened to seal properly.

It is possible (this is just an old man's guess) that you had poor cooling because the gauge indicated it was too high pressure, and the high-limit switch cut out the A/C. By discharging the high side, you may have inadvertently created a leak on the port which can no longer hold pressure.

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