'98 V6 A/C won't turn on

[Flyn67]

Hiya,

So, when I turn on the A/C, the A/C light comes on but there is no A/C. The engine does not come under load as normal when the compressor is supposed to kick on. The fuses are fine.

Before I start tearing things apart, or taking it to the shop, was wondering if anyone had the same issue or may have any suggestions. I could not find anything similar using the search.

Thanks.

[IBMDude]

Most likely cause is that you are out of R134 due to a leak somewhere. Since the compressor won't turn on and fuses (and belt?) are ok, you might want to try this quick and dirty trick to see if you are indeed out of R134. WARNING: I do not recommend doing this at all, but if you want to and it doesn't violate any codes etc. any in your area, make sure you wear proper safety goggles, gloves, etc. and I have never done it myself, just seen a mechanic do it as a quick check. Where the refrigerant line exits the condenser and goes to the receiver/drier, there is a cap labeled H (meaning HIGH Pressure - now you know the warning!). Remove the cap. There is a schrader valve inside (just like in your tires). Find a long pin to depress it very quickly and release it. If you hear a hiss, then it is not out of refrigerant. The next place to check might be the refrigerant pressure switch, compressor clutch, etc. I am way out of my depth in those checks and those might be best left to a good mechanic if you are just a weekend mechanic like me.
Hope this helps!

[proftomda]

First of all, can you hear the compressor engaging when you select the AC button on? It should be a "click" or "thunk" as the compressor clutch releases and compressor begins turning. Is the green light in the AC button on steady or flashing? A steady green light generally means that all is well within the AC system and you have at least enough freon in the system to engage the compressor. A flashing light means a defective speed switch in the compressor. Sometimes this can be remedied by ensuring the propper belt tension. Too tight of belt tension and causes a high load on your compressor and illuminates a flashing green light in your switch. If the light doesnt illuminate at all, you are low on freon for some reason.