Needing a new project to tackle before my exhaust gets here I decided to fix my non-functioning a/c. Long story short I came up with a few conclusions and a couple questions. It was slightly low on R134a, now it's good and its still not working. Tested both high and low pressure switches per jeep factory service manual; good. Tested all underhood relays and fuses; good. I know my blower motor works and can hear and feel the vents moving in the various positions. A/c comp. Clutch will not engage (spins free by hand) and the aux fan is not coming on either. Tested my efan and found out it's open. And that's when I stopped for tonight lol. I was wondering if the a/c clutch won't engage as a safety if the fan will not work. Also was wondering if any year efan will work in my 98 or do I need a 97+ fan. At this point replacing the bad fan is far more important than the a/c working but I was wondering if this could be a cause of the clutch not engaging or should I continue to diagnose the system further in the meantime. Thanks everyone

 

The compressor and e fan may be linked on your Jeep. Supply power directly to the fan, then the compressor, and see if they will engage at all either separately or together.

They may both be bad.

 

The fan is completely shot.. Tried isolating it and supplying power. Nothing. Ohms check it and it's completely open. Still have yet to check the a/c compressor tho.

 

Efan signal comes from the front temp sending unit - on the t-stat housing. It triggers the fan relay when coolant is hot - around 220 degrees.

AND - when the AC switch is turned on, it signals the PCM to increase idle - AND turns on the relay so fan runs regardless of temp.

But if freon is low, compressor still won't come until it's got about 22+ lbs in it - fan or no fan.
How did you determine it has enough?
1 can added statically isn't enough - it will only make it 12-13 lbs or less.

 

if ac compressor will not engage theres no way for you to now if the freons good?

 

I knew the fan was supposed to kick on with the a/c activated. And i initially suspected the charge was low so I hooked up refigerant gauges to it. It was around maybe 20lbs or so and filled it to maybe 35 (dont remember the exact numbers,this was a couple days ago now) and it still wouldn't activate so thats when i started troubleshooting the electrical controls and determined the fan is bad

 

THe jeep only holds like 2.00 lbs of r134a, but the static readings should be approximately room temperature on both low and high when the gauges are hooked up, for a proper charge.