A/C malfunction
 

I just bought my mom a 2003 Ranger XLT 4.0. We thought the A/C didn't work, but today was particularly hot so we had it on just to blow air at us, and after about 5-10 minutes, it actually started blowing ice cold. I thought at first that maybe the compressor clutch had been stuck, and after we turned off the engine, then back on again a few minutes later, it was back to not working until around another 10 minutes driving. I looked at the clutch with the engine running, and it seems to be fine, it just wasn't kicking on. I THINK it's some kind of sensor issue, but I'm not sure, after I flicked the connector at the back of the compressor, the clutch kicked in and was blowing cold again, though it might have been coincidence.

Any ideas?

Nobody?

That connection is the first place I would start looking, could be dirty, corroded or loose.

I had a similar problem with my AC . It ended up being a dry rotted vacuum line. Anytime I got on the throttle to much the AC clutch wouldnt click on.

It's probably low on refrigerant.

As I said, when it finally kicks on, it's ice cold, it seems like it's not getting the signal when to turn the compressor on. So like Supercab said, when I'm feeling better I'm gonna clean and fiddle with the connectors see if that fixes the issue

Low on refrigerant will be COLDER than at normal levels.....................................why?

Because the system works by the cooling effect of Expanding gases.

The compressor does just what it says, it compresses refrigerant which heats it up
Then the compressed refrigerant travels to the expansion valve where its allow to EXPAND into the evaporator, which causes the cooling effect.
When refrigerant is low it can expand MORE, so ICY COLD, this can also cause freeze up, ice forms on the outside tubes and in the evaporator, this blocks air flow in cab vents


There will be two pressure switches, high pressure and low pressure, in the engine bay

Low pressure switch prevents compressor from running when refrigerant is low so compressor doesn't burn out, it needs the oil in the refrigerant to stay lubed
High pressure switch prevents "blow outs" in case of a blockage in the system, i.e compressor stays on until weakest fitting "blows out"

Since the pressure in the AC system changes with outside temperatures, the engine bay heating up could cause low pressure switch to close allowing compressor to run until it opens again, and it would be ICY COLD

You can use an OHM meter to test if a switch is OPEN or CLOSED, they should be Closed, 0 ohms between the 2 switch terminals is what you should see

I had a similar experience with our 2003 4.0. I swapped the A/C relay with the fog light relay and now the compressor kicks in right away. And the fog lights work too, so I'm assuming it was a dirty connection at the relay.

I'll give that a look tomorrow, thanks for the idea