Hi everyone!

Early last summer, I charged my a/c in my 2002 Blazer with a can of 134a freon. It has worked great up until about a week ago. When I put the gauge on, it's reading in the red, which says can be mechanical problems.

Now about the same time, my service engine soon light came on, and I do what every other girl would do....I took it to Auto Zone. They said it was the 02 sensor on bank2. Could this have anything to do with the a/c? I don't want to put any more freon in if that's not the problem.

Thanks in advance!
Joanie

 

O2 sensor is NOT related to the AC.

When you put the gauge on, was it on the high side port, (next to the PCM) or the low side port, (on the accumulator)? What was the psi reading when the compressor turned on? What was the psi reading when the compressor turned off?

 

Hi Captain Hook,

Thanks for replying. I'll be honest. I'm not sure which port I put it on, but it sat on a fat round thing (simply because it was the only port this gauge that came with the 134a can would snap onto). When the compressor was on, it got up to 150, when it was off, it was around 35.

 

The "fat round thing" sounds like the accumulator. But I'm not as knowledgeable as the Captain is.
I'd listen to him & try what he suggests (given him more rep points than anyone).
Normally in my view a charge canister can only go on the port it was meant to go on.

 

As Rottidog mentioned, you were on the low side port, on the accumulator. On this type of AC system, the only way to know how much refrigerant is in the system, is to drain, evacuate, and then install the proper amount. There is no "dipstick". If the system is over or under charged by just a few ounces, cooling efficiency drops. If it's overcharged, it can do serious damage to the compressor, lines, etc. Draining removes most of the refrigerant, evcuating applies a vacuum and removes all remaining air & refrigerant. Refrigerant pressure and temperature are almost the same in the system... (50psi = 50 degrees). If the underhood temperature was 150 degrees, both low and high side ports will show approximately 150psi, when the AC is turned off. Before the system is turned on, both high and low side pressures are equal. The clutch cycling switch is on the accumulator, it constantly monitors low side pressure and cycles the compressor on and off to keep accumulator pressure between 22psi and 42psi when the system is on. When the compressor turns on, high side pressure rises and low side pressuere drops. When low side reaches 22psi, the cycling switch turns off the compressor. Pressure rises on the low side, when it reaches 42psi the cycling switch turns the compressor on and the cycle repeats. When the system is on, low side pressure should cycle between 22psi and 42psi. Maximum high side pressure, while the compressor is on, varies greatly for a number of reasons, it can range anywhere from 150psi to 350psi or more. Best to always use two gauges simultaneuosly so you can monitor both high and low side pressures.

 

Ok, I understand. Is draining and evacuating something that needs to be left to the experts, or could I do it myself?

 

requires a special machine