Ok, I got the dome light working, and the horn. Now I move on the the non-working AC. The fan switch on the dash works, the AC light in the button lights up, but the compressor does not spin. I checked for voltage at the plug end for the compressor, and get no voltage. My other truck shows about 16V at this plug when the AC is on. Any tips on why it might not be getting juice? According to the fuse list, the AC and heat are on the same fuse, but I am thinking that is the dash fan, not the compressor. Thanks for any tips. Hal

Check the low pressure cut out switch. It is on the receiver dryer and they are a weak link in the system. With the AC on tap it with your finger and see if the clutch engages or you could jump the switch.

I am assuming the ac system is properly charged, jumping the low pressure switch with not enough freon and oil could damage the system.
Good luck

Brian

I looked around, found that switch. I think I should test system pressure before jumping the switch. I checked the caps on the refrigerant lines. When I loosened one black plastic cap, I heard a little momentary hiss, so it was holding some pressure back (Not its job). Inside the fitting under the cap is what looks like a tire stem valve. It had a very slight amount of green liquid on it. Is it probable that the refrigerant leaked out of this valve due to a poor valve seal? If I use a Napa kit to check coolant pressure and refill if needed, will the low pressure switch then let the compressor work (If the switch is good)? Will I get more speeding tickets because my truck is red? I know, too many questions. Thanks for any AC tips. Hal

You can buy the valves at an auto parts store and replace them, it's not a big deal if the system has leaked out. If the system is still holding pressure you will need to evacuate the freon before replacing the valve cores.

I would check the pressure in the system first, if no pressure replace the cores and draw a vacuum on the system and check for leaks.

If you have enough pressure I would try jumping the low pressure switch and re-evaluate your pressure readings and amount of charge. Be careful! Running an ac system with low freon and low oil charge is not good.

If it is the low pressure switch they are cheap and real easy to replace. I had one go out the other day so I pulled over and changed it in the parking lot.

Good luck

Brian

How do I know how much oil is in the compressor? How is it added if needed? Thanks.

To know the amount of oil in the system you would need to evacuate the system, flush it and refill with the correct amount of oil and 134A.

If your system is holding pressure and is still charged you should be fine.

There are three ways to add oil. You can evacuate the system and pour it in the receiver drier and put some directly in the compressor and rotate the compressor by hand to work the oil in. They also sell an oil charge that comes in a little can that has an ounce or two of 134a and several ounces of oil that is put in the system the same way you charge it with 134a, and they sell 134a cans that are mostly 134a with an ounce of oil.

If your charge is a little low you might consider buying the 134a can with an ounce of oil. If your charge is really low evacuate the system, find/fix leaks, flush system, replace receiver drier, orifice tube and refill with known quantities of oil and 134.

The main thing I do not want to see happen is you jump the low pressure switch only to find out that the low pressure switch was doing it's job and you burn up your compre$$or. You should be ok to jump it while testing it for short periods of time with out lasting damage.

I bought the Wally Mart pressure gauge/freon installer and checked the pressure in the system. It had about 6 to 8 PSI. I then installed a 12oz can of 134a (Had to jump the low pressure switch for about a minute). I then hooked the low pressure switch back up, and the compressor worked. It took the entire can, and the compressor cycled on and off frequently. I then installed another can, and the compressor ran more steadily, and the gauge showed it right on the line between green and blue. It now blows fairly cold air. I think it needs more 134a to get it into the middle of the blue section on the gauge....properly charged. Now to see if it lasts. Keeping my fingers crossed. Thanks for all of the info that you guys have provided so far! The Suburban is getting better day by day. Now onto a paint question. Hal