A/C Clutch not engaging

[schiker]

Yeah, mine is leaking down as well the cooling is getting weaker and weaker. I might try one more can and hopefully get me through the dog days of summer and get it fixed next spring.

 

[DennisG01]

Yeah, mine is leaking down as well the cooling is getting weaker and weaker. I might try one more can and hopefully get me through the dog days of summer and get it fixed next spring.

If it was just me, I'd do the same thing. But... we've got a vacation coming up in 2 weeks (500 mile trip, one way).... wife, and two small kids... you get the picture!

 

[WarWagon]

Sigh... If it was mine I would just shotgun the SOB. However as you have a 98, your hoses may be good. I usually wind up replacing the compressor, hoses, accumulator and orface tube. And in most cases the condenser. After all when it is 115 out and the AC has failed for the 3rd time in a row...

Common leak points are: High side valve, hoses, compressor, and cracks on the condenser. Every connection has an o ring in it and can be suspect as well.

If it turns out to be the compressor: pay the extra for the accumulator and orface tube to be changed as well. Your system will work better - I just changed a nearly brand new compressor for debris caught in a valve from the last owner going cheap and not doing this when they changed the compressor. Also get a "new" compressor not rebuilt. Trust us - "NEW"!

 

[3500GMC]

A good thread for AC, so here goes...

All is well on oil and 'freon'... Switches are good, 2.5 pounds system capacity. I drew it down, charged 'er up. Kicks right on. COLD too.

Now heres the question: What's it mean when you have to tap the AC clutch with a wrench or something to get it to kick in... is it obvious that I need a new 'clutch'? Is there any 'fixes' other than a new clutch?

It will cycle on and off (via ac control) several times no problem. But every now and then the clutch will kick off and never re-engage unless I tap it with a wrench.

Wiggled the connector at the ac clutch while it should have been engaged, and notta.

 

[WarWagon]

If it has voltage at the compressor coil and the tap kicks it in... The air gap is too big. Remove the nut on the compressor shaft, 14mm. Rent a compressor clutch tool and attempt to move the outer clutch in to the compressor to reduce the air gap - as long as it isn't dragging when hot you are fine. If the clutch will not move in remove the clutch with the tool and remove the spacer washer. The reinstall the clutch and set the air gap close. Install the nut.

 

[3500GMC]

You are on to something there. I remember having the opposite happen with the Camaro, started dragging. It's like those three thin metal blades distort after time.

Off to look for an exploded view of the assembly...

Here is the 'gap'. It does look a little wide.

 

[handcannon]

WarWagon

Going by what you say and the pics that 3500GMC posted, what should that air gap be?

I've got a 97 Astro van that has AC problems. When the motor is cold and underhood temps are low I can get cold air, but as underhood temps go up the AC quits blowing cold air. I'm just wondering if wear has increased the gap to the point that the AC clutch is starting to slip as it heats up and maybe expands that gap.

Don

 

[THEFERMANATOR]

WarWagon

Going by what you say and the pics that 3500GMC posted, what should that air gap be?

I've got a 97 Astro van that has AC problems. When the motor is cold and underhood temps are low I can get cold air, but as underhood temps go up the AC quits blowing cold air. I'm just wondering if wear has increased the gap to the point that the AC clutch is starting to slip as it heats up and maybe expands that gap.

Don

Clutch air gap should be about .010-.020 of an inch, but on used clutches I just remove shims until it will just let the pulley spin freely while still hearing the plate just touch(usually about .005). remove the nut on the compressor shaft and remove the plate and take some shims out until you get the required air gap. Some clutches require a puller to remove the plate to get to the shims. I don't have a GM compressor here to look at to see if you need a puller or not and what kind of puller if one is needed.

 

[handcannon]

Thank you. I will check it out.

Don

 

[WarWagon]

The gap in the picture above is simply extreme.

As the coil gets hot the resistance goes up and the magnetic field is weaker. Thus, a cold compressor can kick in where a hot one will not. Check the clutch hot to make sure it is not dragging. Also if you hear it dragging but the gap appears to be ok, replace it as it is warped. It will drag and overheat the bearing or worse, slip and burn up quickly.

 

[3500GMC]

As the coil gets hot the resistance goes up and the magnetic field is weaker. Thus, a cold compressor can kick in where a hot one will not.

I think that's exactly what's happening. Each time the clutch fails to engage, a tap on the spring/clutch plate will start the A/C. The system works great other than this stupid problem. Cold cold. Fog the windows cold.

 

[Allenm33]

Noticed my AC wasn't blowing cold (this was the first time I had it on this season), so I pulled over and saw that the clutch is not engaging. When I got home I removed the 2-wire plug (on the AC), cleaned the connections and re-plugged the connector back on (actually unplugged and plugged a few times). Still nothing.

I disconnected the plug and measured volts at the plug with the engine running and the dash button "on". The black wire measured a solid 14.2 millivolts, while the green wire's reading fluctuated wildly... between 300mv and 1.3v (the best that I could tell, anyway, as it was fluctuating rapidly).

I can move the clutch by hand, fairly easily. All battery cables/connections are clean and tight.

Am I correct in thinking that I should trace the wires (black and green)? Does anyone know right where they go? Chilton's does not cover the AC system.

Any other advice?

Mine is also not working. Seems no power to compressor and I jump it but clutch doesn't ingage. Where is the fuse for the ac?