'98 AC Compressor Not Working

[2500HD4x4]

Two weeks ago, I bought some NAPA AC refrigerant recharge for my AC. I recharged the AC as instructed, the AC blew cold air and I was satisfied. The truck sat for a week, then upon returning, there was no cold air. I found that the compressor was not engaging at all.

Before recharging the system, the compressor would start, then soon after stop, and continue this start / stop cycle. I assumed this was because the refrigerant was low.

The first day after I recharged the system, the compressor would stay on and blow cold air.

Now, the compressor does not come on at all, and no cold air. The end of the compressor spins easily, but never locks via the clutch. The clutch is relatively new, so I do not think that is the issue. All of the fuses are good, but I am not sure how to check the relay.

Any thoughts would be greatly appreciated.

Thanks.

[jocat54]

You need to check the pressures with gauges, if it is to low the compressor won't engage. You can junprer the low pressure switch on the acummulator to see if compressor will engage, but don't run it to long with switch jumpered. It really sounds like you have lost to much of your charge.

[Bob B]

Same thing happened to my 97. After it lost the new charge, I discovered both valves were not sealing properly.
The low side is a Schrader like the tire valves but better? quality. Easy to replace. The high side has a ball inside and you need to replace the whole stem still easy and wasn't too expensive.
But the caps are important to be there also for extra sealing.
I replaced both caps as the o-rings inside them were cracked.

Bob B

[2500HD4x4]

Thanks Bob. I noticed that one of my caps is not seating well, and has a bad o-ring. I plan on replacing both of the caps as you did. Did you also replace both fittings? If so, what material cost, and labor time was involved?

Thanks again for the help.

[LastOne]

Auto parts stores(Advanced Auto in my case) sell the replacement valves and new caps for around $9.