QuestionHoping for the easiest fix, I just replaced the dash switches for the heater/AC and blower. Now the blower works OK but no A/C. My wife assures me that it would blow cold air now and then, but not lately. What's the next thing I should look at? Do these systems have a typical failure part? We have a '91 Jimmy that had the exact same problems so I'm guessing there's a common weak link. Thanks.
AnswerMerle,
Unfortunately until you have had your hands in the A/C world for a few years, there is no easy fix or troubleshooting. But I will lead you in the right direction as best I can. It may require a couple follow-ups on your part though.
The first thig I need you to do is to locate your low pressure switch. This is located somewhere on your low side line. Either directly mounted to a hard portion of the line itself, or on your accumulator. Your accumulator is an aluminum canister about the girth of a soda can with two hard lines coming from the top of it. It should be located on the passenger side of your engine compartment close to your strut tower. Once you locate your switch, unplug the harness from it and with the key in the run position (engine on or off) and the a/c switch and blower motor on, with an insulated wire jump the terminals inside the harness plug. When you do this you should hear a snap from your compressor clutch engaging. If you do, this tells me that either your low pressure switch is faulty and not closing the contacts when it should, or more likely, your refrigerant charge is too low to close the contacts in your pressure switch. If it does snap first check your refrigerant charge and have it charged if it is low.
If it did not snap, let me know, and I will give you the run down on the electrical system. You will need a multimeter to do the checks I give you in the next reply. But I believe that if you changed the controls already, wired them correctly, and your wife said that it used to cool occasionally you will find you have a low charge in your system. This will also mean that you have a leak in your system that should be found and repaired.
I have to say this so bear with me... DO NOT, DO NOT, DO NOT leave this switch bypassed for normal use. it is a vital safety component that protects your compressor and may cause serious damage to your compressor if left bypassed.
I hope I helped you a little, and if you need anything more, please let me know through a follow-up. Thank you for the question and good luck.
