A/C Troubleshooting

[Smoky1978]

Hey everyone

I have a 97 Explorer 5.0 AWD

I'm basically looking to make sure my findings are correct.

I am only using one of the gauges from the Freon refill kits

So this is what I have come up with so far. Fill the system with freon to I think about 250 on the gauge don't quote me. I turn on the A/C and the A/C clutch engages the pressure drops to 172 and the Clutch disengages. This continues. But no cold air.

So than I tried jumping the low pressure switch A/C Clutch stays engaged but the pressure ends up dropping to 0. No more freon. I did check there is pressure on the high side.

So my main question i guess would be am I looking at a leak or could it be something else? I tried following all the plumbing and i could not find anything dripping or wet at all. If there are any known spots for the leak? or should i just bite the bullet and buy one of those UV leak detection kits. Thanks in advance for your help

 

[ranger7ltr]

I would recommend renting or borrowing a proper set of gauges to monitor both the low and high pressure sides of the refrigerant system and charge only into the low side of the system...Using the "Cool in a can" solution is one of the tools that make A/C specialists busy as they are called Death Kit in a can...

The system will equalize pressure-wise when the compressor is not running... When it does have enough refrigerant in the system, assuming there is not another problem, you do not need to jumper the low pressure switch in the system...

But I DO question the numbers you are getting... If you read 172 psi on the low pressure side of the a/c system I would be very surprised and worried that there is a blockage somewhere inside...Was this gauge reading from the fitting on the accumulator [the black or silver colored "can" at the front of the black plenum on the passenger side or from a fitting on a thin line coming from the condenser on the drivers side of the engine bay?? With proper gauges you would see the pressures equalize with the compressor off then when the compressor is running the low side will drop into 20-60 psi range and the high side rise into the 175-300 psi range depending on the ambient temp at the condenser...

With the conditions you saw I believe you must have a gauge on the high pressure side and when the compressor engaged the refrigerant starts to flow...With the compressor running, if you saw 172 psi and then the compressor clutch disengaged, the system is trying to cool and the clutch will cycle on and off to move the refrigerant through the system to remove the heat it picks up at the evaporator inside your truck...When it quick cycles, there is usually not enough refrigerant to start and continue the cooling process but there is enough to close the low pressure switch and allow it to supply power to the clutch...With the "0" pressure you saw was that when the compressor clutch was engaged and then when the gauge drops to "0" the clutch kicks out? If so, that is a dead giveaway that there is not enough refrigerant in the system...

BTW the high side pressures will be 2.3-2.7 times the ambient temperature in a properly running system...A weak or dead fan clutch, missing fan shroud, dirty or clogged cooling system, and dirty or clogged condenser and/or radiator fins will slow the heat transfer from the condenser and degrade your a/c systems ability to function... Don't overlook these items as well...