AC and defroster problems

[rbsteve]

With the warm weather coming around, there must be alot of AC related questions....please allow me to throw mine into the mix...

When i turn on my AC, nothing happens, the compressor clutch doesnt turn on, obviously no cold air comes out of the vent and the engine cooling fan doesnt turn on.

Also of note, when i turn my defroster on, neither of the cooling fans turn on. Are these two problems related ?

I have checked the 3 big fan relays under the hood and also the AC CLU relay by passing 12V over the 85-86 pins and hearing a distinct "click". Also i measured the resistance across the other two terminals and it went from open circuit to around 40-50 ohms.

Does anyone know what could be causing this, and why my fans dont turn on?

Thanks a bunch

-Steve

PS 98 GP 3.8 Not s/c with digital climat control.

[BNaylor]

Best thing to do is check the refrigerant charge at the low side port. If low the compressor will not turn on due to the hi/lo pressure switch sensing low refrigerant level. Problem sounds related because the PCM looks at the signal from the pressure switch to turn on the engine cooling fans in addition to monitoring engine coolant temperature.

[richtazz]

I agree with bnaylor. Be careful using one of the cheapo generic guages from Auto-Zone/Advance. They are not very accurate, and don't compensate for ambient temperature (which affects what the correct pressure should be at any given time). Spend a few extra bucks and get one that has a chart for ambient temperature compensation.

[rbsteve]

A couple of years ago I bought a refil kit that came with a can of refrigerant/oil/leak stopper and a hose with a built in gauge. It may have not been the most accurate, but after i refilled it, the needle was in the higher side of the green zone and the AC had worked fine for 2 years...until now.

I just bought another refil can, attached the hose and measured the pressure without trying to add refrigerant. It came up low, so i tried squeezing some refrigerant in, but i could tell it wasnt flowing.

How do you add refrigerant if the compressor isnt running ? And if the level is that low, does it probably mean i have a large leak and isnt worth trying to add more ?



-Steve