Another A/C Issue

[kanarmAN]

My father inlaw has a 98 x and the ac pump doesnt seem to kick on. Blower works on all positions. He also changed two relays under the hood? A mecanic at murlins said it there wasnt proper pressure compreser wouldnt kick on? The ac worked just fine intil it just started blowing warm. lol makes perfect sense. Any info is greatly apreciated..Don

 

[drdoom]

All I know, is that my brother told me A/C systems have a Low Pressure Switch, and when the charge is low, the compressor will not kick on. The switch is located on the accumulator, it has wires going to it. Years ago, my compressor would not kick on, so I added a can of R134A and it started working...for a while. Then it would leak down, so I took the UV light, and determined the the accumulator was bad. So then I GOOGLES it, and found enough info to reinforce my "diagnosis". YMMV
Best wishes.

 

[Lube]

All I know, is that my brother told me A/C systems have a Low Pressure Switch, and when the charge is low, the compressor will not kick on. The switch is located on the accumulator, it has wires going to it. Years ago, my compressor would not kick on, so I added a can of R134A and it started working...for a while. Then it would leak down, so I took the UV light, and determined the the accumulator was bad. So then I GOOGLES it, and found enough info to reinforce my "diagnosis". YMMV
Best wishes.

^Truth here.
One thing to remember, if you have a refrigerant leak, you also have an oil leak. Oil in A/C systems circulates throughout the system with the refrigerant. You might get away with just recharging it, and not adding any oil...and you might not. Compressors aren't cheap, but oil is. Putting a 2 ounce bottle of oil in the system after you've found and fixed the leak is cheap insurance.

The real, proper fix here is to evacuate the system after determining where the leak is. I know the law says you have to recover the refrigerant, but the A/C police have been noticeably absent in my neighborhood. Blow the remaining refrigerant charge by hooking a hose to either the high or low pressure connection. Don't hold the hose so it will blow on you, or you could end up with a NASTY case of frostbite. Fix the leak, evacuate the system with a vacuum pump. You want as deep a vacuum as you can possibly get, 29.7" minimum. Make sure the system will hold vacuum by turning off the vacuum pump and closing the valves and watch the gauges (you are using a charging manifold, right? Harbor Freight is your friend). You should maintain vacuum for at least 30 mins with no drop to be reasonably sure there are no leaks. If vacuum drops AT ALL, you have a leak somewhere that still needs fixing. Now, charge the system with the recommended amount of refrigerant. A kitchen scale is handy here, as I've seen cans of 134 that didn't have as much in them as the can label said they did. The gauges that come as a "charging kit" from the local parts store are only useful as a doorstop, and don't tell you much, if anything, useful about the state of charge in your system. There are other variables that may be present that these "kit" gauges don't take in to account.

Common leak points are:
Any mechanical joint in the system.
The Schraeder valves in the high and low pressure charging connections.
The compressor shaft seal.
The compressor case seal (where the 2 case halves meet).

Good luck!

 

[kanarmAN]

Thanks Thats great info at the very least if we take it to a shop? We have a heads up.

thanks again