AC Troubleshooting - Clutch Engages Then Turns Off Immediately

[redrangerbluemiata]

Howdy folks,

Trouble with the AC system in my 2002 Ranger XLT w/ 4.0L SOHC. Pictures of the gauges are attached, don't know if I did that right. When I turn the cabin switch to "AC" I get 13V at the relay. Clutch engages and pressure spikes for about half a second, then it goes off again. Leading theory is a clogged orifice tube after doing some research on other threads here, but I wanted to post the gauges to see if anyone had a better idea. Low side too low, high side too high.

 

[pjtoledo]

low is too low? from a 2005 manual, should be the same for a 2000.

I'm not an AC guru, I'll let the experts comment on the readings.

 

[RobbieD]

Common symptom, and the most likely cause, is a low refrigerant charge.

The compressor engages, and the low side pressure drops enough to open the low pressure switch, which cuts out the compressor.

I don't have the specs for your year, but the low gauge going below 20 as the high gauge spikes indicates the low charge scenario.

 

[redrangerbluemiata]

low is too low? from a 2005 manual, should be the same for a 2000.

I'm not an AC guru, I'll let the experts comment on the readings.

View attachment 143895

View attachment 143896

Thanks for these, I was having trouble finding good tables online. If I am reading this right, then low side at 72F should be between ~27-46 psi, when the compressor is on my low side gauge drops to 16 psi. High side should be ~130-230 psi and mine spikes to ~240 psi then the compressor cuts off. Sounds like I'm tripping a high pressure cutoff switch?

You said these are from the manual? Previous owner lost the manual, I outta pick one up.

 

[redrangerbluemiata]

Common symptom, and the most likely cause, is a low refrigerant charge.

The compressor engages, and the low side pressure drops enough to open the low pressure switch, which cuts out the compressor.

I don't have the specs for your year, but the low gauge going below 20 as the high gauge spikes indicates the low charge scenario.

I also thought low refrigerant so I started throwing another can in before I got the gauges, and refrigerant started spewing out of the pressure relief valve. I think because charge is good, then the next thing would be a blockage in the system (clogged orifice tube).

 

[RobbieD]

Make sure that you're not trying to add refrigerant to the high side! Low side only; the pressure relief should not have opened when you tried adding some.

Just off the top of my head, I think a blocked orifice would overpressure the low side.

@pjtoledo posted pages from his shop manual, not owner's manual.

You really should look at getting a shop manual for your truck, especially with working on something like the A/C.

 

[redrangerbluemiata]

Make sure that you're not trying to add refrigerant to the high side! Low side only; the pressure relief should not have opened when you tried adding some.

Just off the top of my head, I think a blocked orifice would overpressure the low side.

@pjtoledo posted pages from his shop manual, not owner's manual.

You really should look at getting a shop manual for your truck, especially with working on something like the A/C.

I definitely added to the low side only when the relief valve opened. I didn't even know where the high side port was until I got the gauges yesterday. I had the relay jumped so the compressor was on while I was filling.

Low pressure on low side, high pressure on high side (to the point of opening pressure relief) to me indicates that refrigerant can flow from the low side to the high side but gets blocked trying to complete the cycle from high side back to low side.