Hi all,
I've been having a problem with the A/C in my 1999 Ranger 3.0L for some time now. With the help of this forum, I've tried all I can to resolve this, and I'm running out of luck so it seems.
The problem is the compressor sometimes cycles like it should and other times it wont at all. I've determined that the compressor is not frozen up, the system has a good charge I think (45psi on low side measured today), and I've replaced the clutch cycling switch. I've also applied a good amount of dielectric grease in all the connections (low and high side switches and compressor connector).
To add some detail about the problem, a few nights ago it was cool and rainy and of course my windows fogged up. I turn on the defrost and the compressor didn't click on, so no defrost. The night before it worked fine. This is not the first time this has happened either. Before to fix it all I did was apply the dielectric in the connections. Today, the conditions here in central KY is bitter cold, 26F, 76% humidity, and the dew point is 20 degrees. Does theese conditions affect the operation if the A/C. I mean would it being so cold make it not work? By jumping the low side pressure switch the compressor comes on, then when I plug it back into the switch it works normal, cycling every minute or so for about 6-10 seconds. When I turn the truck off, and start it back, nothing....it doesnt work again. I've let it idle with the defrost/acon, and it won't cycle.
I've got a couple 12oz. cans of r134a but the gauge on the hose says 45psi and thats right at the top of the filled area, so I guess that means it's charged good???


Any advice, help will be greatly appreciated. Sorry for the lengthy post.

Thanks,
Chris

 

I can think of a couple things that would cause this and they're all electrical. the pressure switch does exactly what it sounds like. If the system pressure is good then the switch will open and allow the system to turn on. If you switch is faulty then it may be getting stuck. I'm not 100% on this but you should have a 3 wire switch. Short the outside lines together and the switch should remain open/on and allow the compressor to work normally (if the jumper you use to short the connections starts to spark or get hot then remove the jumper line immediatley). If nothing changes then your switch is probably not at fault. the only other thing I can think of is a bad power wire going to your compressor. Remove your wires and check them one by one with an ohmeter. If a wire looks suspect then replace it. Aside from that I can't offer any other suggestions.

 

45lbs is at the top of the fill range. Normally these systems need to be around 30lb low side to operate normally.

It would help to know your high side pressure.

The condenser temp will be lower with low outside(ambient) temps. Rule of thumb is <> 130/160@60*ambient. The system will still work even at your 26* temp.

The somethimes works normally, sometimes doesn't is indicative of an electrical intermittent. This could be anywhere in the system. If you are getting voltage to one side of the low pressure switch any time the system is turned on, this would indicate the problem is from the switch to the compressor. If not, the problem is from the switch back to the voltage source for the controls.

This system also has a high side pressure switch. Make sure it is not triggering early.

There is a separate A/C forum on this board. Post there and you can possible get more help. jd

 

The owners manuals ('95 and '96) I've looked at says the A/C compressor won't come on in the defrost position if the outside temperature is below 50 degrees fahrenheit. Check your owners manual.

Good luck.

 

Yep, checked mine and thats what it says too. Guess I'll wait till it warm up and see if the problem (if there is any) is still there.


Thanks for all your help!


Chris

 

If you do find you're still having a problem, I'm going to need to know BOTH the low and high side readings and the outside ambient air temperature while the compressor is running... You may have a restriction somewhere or just a crapped out compressor.

 

Thanks...If I still have problems when it warms up a bit, I will get a manifold gauge and give the readings.

Thanks again,
Chris