Please Help On A/c Problem

[RX300MS]

Greetings, everyone.

Our 99 RX300's AC started not working about 4 days ago. I went to the auto zone and bought a can of R134 and put it in. I bought the kit with pressure gauge so I was able to read the pressure. However when I charge it, I might have added a little bit more (the reading says it's in alert range). That was yesterday. Today I took the gauge and tried it again. At first the readings was in the alert range. Then it dropped to green area (which means it's good). So I think I did not put too much of R134 in.

But apparently, adding 134 did not work. If I turned the car on and put the AC to max (with air mode to be circling), the AC turned on for about 2, 3 seconds, and then the circling air light turns off along with the AC. It's very weird to me, as I tend to think that the AC light should be off.

Could anybody explain me why it's doing this? I think I should take it to the pros, but would like to know what's happening first.

Thanks very much!!

Ryan

[rlin78]

Greetings, everyone.

Our 99 RX300's AC started not working about 4 days ago. I went to the auto zone and bought a can of R134 and put it in. I bought the kit with pressure gauge so I was able to read the pressure. However when I charge it, I might have added a little bit more (the reading says it's in alert range). That was yesterday. Today I took the gauge and tried it again. At first the readings was in the alert range. Then it dropped to green area (which means it's good). So I think I did not put too much of R134 in.

But apparently, adding 134 did not work. If I turned the car on and put the AC to max (with air mode to be circling), the AC turned on for about 2, 3 seconds, and then the circling air light turns off along with the AC. It's very weird to me, as I tend to think that the AC light should be off.

Could anybody explain me why it's doing this? I think I should take it to the pros, but would like to know what's happening first.

Thanks very much!!

Ryan

You might still have a little bit too much pressure in the system, is the AC compressor fan running or not? If it is not running or runs and then shuts off right away, that means the high pressure sensor is preventing it from running to protect the system. You need to "properly" reduce the pressure to normal pressure, then enjoy the cold air. Let us know how it works out.

[RX300MS]

Well, I heard that it's very tricky to let some out, it might damage the valve and also dangerous. I don't know what I should do now. May eventually take it to a shop.

The AC comes on with big fan noise for about 2, 3 seconds and then shuts itself off. Sounds like what you said about the high pressure.

I will let you know what happens next.

Thanks so much!!

[rlin78]

Well, I heard that it's very tricky to let some out, it might damage the valve and also dangerous. I don't know what I should do now. May eventually take it to a shop.

The AC comes on with big fan noise for about 2, 3 seconds and then shuts itself off. Sounds like what you said about the high pressure.

I will let you know what happens next.

Thanks so much!!

If you do it on the low side, it is not dangerous. Use the side where you added the R132A. Using the high side can be very dangerous, I have no proof of that because I am too chicken to try it. :)

Not to name any names to protect the innocents ;) , I know someone that had the same symtoms and he used a phillips screw driver to relief the pressure until the fan would continue to run. AC was blowing very cold. It is up to you, you can save your money or take it to a shop. I am not encouraging you to take a chance, you should "always" trust a licensed tech to work on your car...:whistles: Warning, reliefing your AC using the method mentioned here is illegal in most states, and should be discouraged. You could also be fined a large amount of money.

[wwest]

Well, I heard that it's very tricky to let some out, it might damage the valve and also dangerous. I don't know what I should do now. May eventually take it to a shop.

The AC comes on with big fan noise for about 2, 3 seconds and then shuts itself off. Sounds like what you said about the high pressure.

I will let you know what happens next.

Thanks so much!!

If you do it on the low side, it is not dangerous. Use the side where you added the R132A. Using the high side can be very dangerous, I have no proof of that because I am too chicken to try it. :)

Not to name any names to protect the innocents ;) , I know someone that had the same symtoms and he used a phillips screw driver to relief the pressure until the fan would continue to run. AC was blowing very cold. It is up to you, you can save your money or take it to a shop. I am not encouraging you to take a chance, you should "always" trust a licensed tech to work on your car...:whistles: Warning, reliefing your AC using the method mentioned here is illegal in most states, and should be discouraged. You could also be fined a large amount of money.

In "max cool" position the compressor should run unless:

A) The dual function pressure switch indicates a system pressure so low as so the compressor would be damaged due to low/no refrigerant flow. Clearly NOT what is happening here.

B) As the compressor runs the refrigerant pressure on the high side increases to a maximum level at which time the compressor clutch circuit is opened due to the other function of the same pressure switch. As the liquid refrigerant is metered to the evaporator core and boils away the high side pressure declines to the point wherein the compressor is again cycled on..

You may have a blocked metering valve to the evaporator.