I have a 2004 XL 4.6 that stopped blowing cold air!. When I was checking under the hood, I noticed that the compressor would lick in for a couple of second, then kick out. It kept this up as long as I had the engine running. Any ideas what could be causing this?

 

Lots of things can cause that. It could be a bad electrical connection, low/high pressure switch, thermostat, poor air flow across the thermostat, or expansion valve. You really need to hook some gauges up to it though and see whats going on.

 

Low refrigerant. Bad compressor clutch control switch.

Put a manifold guage set on the low-side and high-side ports, start the engine at fast idle, MaxAC, medium blower speed. Look for low-side cycling ~27psi clutch off to ~47psi clutch on with high-side near 200psi.
If the low-side pressures are not withing these limits, the pressure switch is bad and needs a replacement....an easy job and fairly cheap. A BWD unit from Advance Auto Parts works.

If the pressures on the low-side look good and the high-side pressure is low, the system needs refrigerant, R134A.

Of course the switch could be bad and the system low on refrigerant as well....the guages will tell the story.

You will want to check for evidence of refrigeration-oil leaks....the compressor shaft seal is a candidate as well as any of the connection fittings you can see in the system. If there is a major leak, then some serious AC maintenance is indicated, preferably by a pro.

 

Looks like a set A/C gauges are in my future!

Thanks,

Oh, and where would that pressure switch be located?

 

The switch should be located on the top of the accumulator/dryer cannister....at least it is on my '97; however, it may be located anywhere on the low-side plumbing.

 

I think i have these gauges figured out. The low side is cycling from about 20 to 40 and the high side just over 100. I'm guessing I need to add some .

Do any of these stop leak products work or would I be messing things up further?

Thanks

 

Here's the latest. I added a can (most of it) of r134a and the cycling reduced to about 10 sec on and 8 off. The readings on the gages were; low side: 40 on, 20 off, high side: 100 on, 125 off. Am I still low on refrigerant or should look at my switch? Ambient temp is 75 deg and the engine is running at idle. Thanks