1997 Z71 A/C power issue

[Smokindog]

I had the compressor on my 1997 Z71 replaced a few years ago. After that replacement the A/C would only come on after the truck warmed up. I took it back and the dealer said one of the connectors had been cracked and was only making a solid connection after it heated up. They said they replaced it and all was well for a few years. It only took about 15 minutes to affect the repair while I waited so it must be a fairly accessible electrical connector. He described it as the pin getting pushed out the other end when reconnecting. UNFORTUNATELY, I didn't make the dealer show me which connector.

I recently had a new water pump installed and now the A/C is doing the same thing, typically coming on after I drive, park, and then go on to the next location.

I tried to follow the wires from the clutch (my guess from the dealer description years ago) but am having no luck.

 

The A/C works wonderfully once it engages. It's as though some metal in a power connector needs to sufficiently heat and expand to make a solid contact. Once that happens the air is cold and strong and consistent until the engine cools! That means my trip TO the store is usually uncomfortable but once I come out of the store and resume my errands I've got awesome A/C. Pretty predictable that way!!!!!

That's why I made sure to include the original diagnosis of a connector that was cracked allowing a pin to get pushed out when reconnected. I suspect when they replaced the water pump they had to disconnect this same connector while removing things and when they put everything back together the pin again was partially pushed out of position.

 

I need help locating the connectors in the electrical path to the clutch (or identify other connectors that may be the culprit). Pictures would be awesome as the wires go into the combination wire wrap bundles and I'm having difficulties tracing what I need.

[thx1138v2]

I don't have a '97 so I can't give you the exact locations. Generally there are three A/C switches under the hood that affect the A/C.

 

1. Clutch switch which you have found.

 

2. High pressure shutoff switch that turns the compressor off when a refrigerant over pressure condition occurs. I believe it is connected to the smaller aluminum refrigerant tube that goes from the compressor to the condenser coil by the radiator. The switch is at the compressor end of that tube. It could also be on the end of the compressor opposite the clutch. This one may be hard to see from the top, depending on how your compressor is mounted.

 

3. Low pressure shutoff switch that turns the compressor off when a refrigerant under pressure condition occurs. This one is usually at the A/C hose connection to the accumulator/dryer that's mounted on the firewall.

 

I don't think connector #3, near the firewall, would heat up much since it's quite a ways from the engine and usually just sticking out in the air. But connector #2, near the compressor, could get hot since it is near the engine and water pump. And you mentioned the water pump being repaired so that would be the first one to check.

[barry G]

the water pump is the only pulley that cannot align. you may now have a stressed out clutch engage.. but unlikely.

 

air bound, tiny amount, can do the delayed shutoff.

those should kick on all the way to near freezing when done right.

I fixed my own with a couple of refills at home with pumps and gauges before i got it.

 

my first attempt, it was doing what yours is doing now. Slightly polluted refill.

[arcasey]

It's been a while since I changed the water pump on my 96 but to the best of my knowledge there were no electrical connectors that had to be removed in order to replace the water pump. Mine was doing something similar to what you described and my mechanic fixed it by replacing one of the pressure switches and checking for proper refrigerant charge. Don't know which switch it was and it may have been both, I just can't remember.