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Ac Question That Has Me Baffled

dougg01

By dougg01
in Ask A GM Technician

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dougg01 Enthusiast

dougg01

Posted
Posted

Hate to ask an AC question, but this thing is weird.

 

Backstory - 97 Blazer (s-series) leaking from schrader (unknown) and won't stay charged. Ultimately I swapped in a new accumulator and the compressor from my Jimmy (known to be good). The Blazer showed some green (under blacklight) around the compressor so that is why I decided to swap. Added new Schraders.

 

Vacuumed three times just to be sure with no leakdown.

 

Added oil.

 

Added refrig.

 

Blowing crazy cold, pressures are great (idle and ~1,000rpm), and I'm happy. Blacklight doesn't show any leaks and I have clear windows on our humid mornings.

 

Yesterday I had cold air driving in from work. Stopped at Wally-world for a perscription and when I leave the parking lot I notice no cool air. Switch off/on and nothing. Great. It's 90-something, humid, and I am in work clothes being unhappy.

 

Get home...compressor isn't engaging. No click or anything. Jumper the pressure switch - still nothing. Check the relay - its fine. Swapped relay anyway for a spare. Checked fuses - some tarnish....nothing that would stop a connection. All the hoses are underhood temps. I showed ~100 on each side.

 

When the switch is engaged the tuning adjustments are made (noticeable) as if the PCM thinks the AC is turning. It returns to normal when the switch is off. I had power at the clutch switch.

 

I gave up for the night.

 

Went out this morning, tried the defrost, and I heard the thing cycle....!!! Checked pressure and it was a little low (no, I didn't have the jumper still in place) so I added a bit and the thing kept working fine. Argh. When I went to attach the hi-side hose before adding refrig I had some venting as I unscewed the cap. I didn't take the time to check static pressures - I was already late.

 

What gives...? I know that I'm no expert on this stuff, but c'mon, I followed the steps per usual and connected the dots. I don't care for getting hot on my commute, but I live in the hilly sticks and my windows don't clear in the mornings until I hit the main road even with the windows down if I don't have a defroster. That's bad news with the deer plotting to remove this truck from my ownership.

 

Help please.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

If you have power at the clutch, but no engagement, then you need a new clutch coil. It probably failed to operate after getting real hot under the hood while you were shopping. Next morning, it cools down & works again. Common problem.

dougg01 Enthusiast

dougg01

Posted
  • Author
Posted
If you have power at the clutch, but no engagement, then you need a new clutch coil. It probably failed to operate after getting real hot under the hood while you were shopping. Next morning, it cools down & works again. Common problem.

 

Clutch coil is something I can replace myself...? I ask because it's not something I've done. For me it's been the clutch works or it doesn't....new comp time.

 

I'll look.

 

thanks for the reply. The engine runs good temps, but yesterday it was quite hot outside and I ran it hard so the heat-soak when I stopped could have been rough if the part isn't up to par.

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

As long as you have the tools for pulling the outer plate off you can do it yourself. For the life of me, I cannot remember the proper name of the outer plate, but it is a press fit, and must be reinstalled with the proper clearance after changing the clutch coil.

BTW, there are a few parts in that area that can be replaced without buying new compressor.

dougg01 Enthusiast

dougg01

Posted
  • Author
Posted
As long as you have the tools for pulling the outer plate off you can do it yourself. For the life of me, I cannot remember the proper name of the outer plate, but it is a press fit, and must be reinstalled with the proper clearance after changing the clutch coil.

BTW, there are a few parts in that area that can be replaced without buying new compressor.

 

So, this is my DD and my spare is still on stands in the garage.

 

From what I can glean so far the clutch needs to be removed, then a snap ring, and pull the plate off to access the coil assy.

 

What kind of tool is needed to remove the clutch...? What about air gap on the clutch if I am not replacing it...?

 

New stuff to me, but I am not afraid. My AC unit is on top, drv side so it might be wise to leave it mounted so it doesn't wriggle on me.

 

Wonder if I can use the coil from my old compressor......

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