AC not working, clutch disengage after 5-7 sec

[monster_ford]

I have a Mercury Mountaineer -02 and the AC is not working.

Been reading a lot of threads here on the forum about the problem, but wanted some (hopefully) questions answered.

My AC clutch engage/disengage every 5-7 sec. The answer around the forum seems to be that its low on pressure.
But the previously owner took it to a store and they filled it and did not found any leek. (A professional store that only deals with auto ac) last year in may.

Is there anything else that could be creating this problem?
(It feels like a wast of money to check the pressure again and get the answer that its OK, but maybe its the only way to go?)

Is there a way to check if the low pressure switch is working properly?

 

[blueoval9erlifer]

Last May was a year ago so it could be low. In the evaporator canister area there is a plug that if you take it off you can take a short piece of wire and short the two across. Im not sure which two wires you want to do it to but by doing this it eliminates the high and low pressure switches to where it will make the pump run if there is enough freon to kick it in.

My 1st suggestion is to look around someone usually offers a free A/C CHECK and then they will tell you what it will cost to fix it.
Also always make sure that you are washing out your condenser and radiator yearly. This will make a huge difference in how much it cools and how hot your vehicle runs. My friend who runs a garage always tells me that 75% of his A/C business is taking his garden hose and washing out the condenser. because people are too stupid or lazy to do this.. Just make sure not to use a pressure washer because you will mess up the fins on the condenser..

Hope this helped.

 

[JoshMcMadMac]

You need a set of pressure gauges to properly diagnose, but it sounds like low refrigerant. If the previous owner had to have it "filled" then there is a leak; the refrigerant has to go somewhere. The easiest check would be to put a gauge on the low-pressure side and watch it as the compressor engages. I would guess you would see the gauge needle fall until the compressor cuts out on low pressure, the needle rise until it resets, and repeat.

 

[rocco123]

I agree that sometimes you have to bypass the switch to get it to take a charge

 

[monster_ford]

Ok thanks for the advice and help!

I will take it to a AC store and let them have a look.

I understood it from the previous owner that he did not have a working AC and took it to a store and they drain and refilled the system, but that did not make any different, it was not working then either.
The owner died so I have only talked to his child, and he did not know for sure.

When the clutch engages there is a little vibration that I can feel when my hands is on the front of the car and a small "pyyysch" sound. Maybe thats normal?

 

[Donystoy]

I am just in the process of repairing the A/C in my 2002. I found the leak in the side of the receiver drier (aluminum cylinder) that is in front of the engine air filter housing. It was leaking about 2 inches up from the bottom behind the insulation. Acid in the oil over time will corrode these from the inside out. This is frequently caused by improper evacuation during a previous service. I strongly advise anyone who works on their own systems to at a minimum ask some one qualified for advice or better yet take it to a shop that specializes in automotive A/C.

There is no economics in continually dumping in refrigerant only to have it leak out. Also as soon as the refrigerant starts to leak out the return temp. to the compressor steadily increases. This lack of cold suction gas will over time also result in lessening the life of the compressor. As the refrigerant charge gets lower, the low side safety switch will start to operate causing short cycling lessening the life of the electric clutch. There is also the danger of getting liquid refrigerant on your skin or worse yet in an eye. This can happen while undoing a fitting or explosive discharge due to an overfill.

Not to scare anyone but I worked in this industry for 34 years and have seen it all.