AC cuts off over 45 MPH

[envisionelec]

Works perfectly at idle. Cuts off at 45 MPH, on the dot. It won't come back on until I'm idling.

I just replaced the cycling switch which helped it cycle regularly at idle. But that's only a small problem.

I have not checked system pressure because my thinking is that the pressure is greatest when the system is hottest which is at rest, not at speed. Flawed theory?

 

[MacMan]

Check the pressure. Maybe a simple re-charge is all that's needed.

 

[c good]

not really a flawed theory but doesn't apply in the case of our AC system unless something has gone bad ie fan clutch, fan call parameters etc. Pressures do go up in the system when it gets hot but there are systems designed to keep it in a general operating temperature/pressure range. You really do need to put a set of gauges on it before you go any further in your troubleshooting our you are just wasting time. Hi and low side Gauges are put on the system, AC is turned on high fan/max cold and an approximate RPM of 1500 to get a decent reading then go from there. HTH c good

P.S. If you have good 134 level, and it continues to cut out after 45 mph, it's probably not speed related, it's temperature related. If it cuts out only after it warms up then you've got the bad clutch coil assembly problem common on these models. Let us know what you find out and we'll go from there.

 

[envisionelec]

Ok - I put the gauges on and everything looked great: Low Side was at the top of "OK" but not into "High" at all. Blowing nice and cold. Got the engine locked into 1500RPM. By the time I came around to the gauges, the low side had dropped to the borderline "Too Low" area. I'd give you the PSI, but it was dark and I wasn't wearing my glasses (sorry...limited time). The high side remained good...then the compressor dropped out. The Low Side spiked up into the "Too High" and high side dropped to the border of OK and Too Low. I tried to get the compressor running again by jumpering the cycle switch, but I'm thinking there is a high side cutout that prevents operation. OR the clutch coil overheated.

I can give you more precise details tomorrow when the sun is out.

 

[c good]

What year and model do you own? Didn't see it in your profile. c good

 

[envisionelec]

What year and model do you own? Didn't see it in your profile. c good

Sorry, I hadn't set that up yet.

2002 Bravada

 

[envisionelec]

I figured it out. I used a wooden stick to press the clutch plate - and it engaged! I just barely tapped it. So it appears that I have the "air gap" problem. Is it possible to pull the shim out of the clutch without removing the fan and fan shroud?


I found this thread which might be helpful for finding parts: http://gmtnation.com/f23/ac-compres...lacement-parts-advice-[2002-envoy-slt-]-3034/

Clutch# is 100PV6. 100PV6 may have nothing to do with the coil assy. 100mm diameter clutch, 6 V-Grooves.

A company called Action Air shows a part number for a replacement clutch coil. It may not be a stock item.

This might be the same thing.

TRS105 might use the same clutch assembly. If someone can check on this, it would be greatly appreciated.

Exploded view.

Video.
I'll keep updating this thread with more information as I find it.

 

[c good]

The shims are #32 in your diagram. What "shroud" are you speaking of? great links BTW......

 

[envisionelec]

The shims are #32 in your diagram. What "shroud" are you speaking of? great links BTW......

The fan shroud. I'm not sure I'll have enough clearance if I leave the fan and shroud in place.

 

[c good]

I had a friend that owns an AC shop put the new(used)compressor in for me. I don't think he pulled the fan shroud, but what he did was R&R the compressor. Removing the front of the compressor(clutch/coil assembly) is a whole different animal. You'll have to take a look at it and see if you can get an air rachet up in there.

 

[envisionelec]

I am mechanically inclined, but I certainly don't prefer to wrench around on cars. That said, I finally got the courage to go tackle this problem...and I fixed it in 10 minutes. 5 minutes of that was finding something suitable to hold the clutch face still while I unbolted it. I grabbed a "pickle fork" (ball joint removal tool) and straddled the socket with the fork's "mouth" while pressing it against one of the rivets in the clutch face. There was but one shim installed, but the clutch did not rub when re-assembled.

Result? Perfectly cold air. And on a 100 degree day, it was welcomed.

 

[Sparky]

So wait, you got it off without taking the fan shroud and assembly out? If so I want to know how! I need to replace the pulley bearing on mine but given that I thought I had to remove everything to get to it I was waiting until I had the time, funds, and parts necessary to do a major overhaul of my cooling system.

 

[c good]

Sweet.....glad it worked out.

 

[envisionelec]

So wait, you got it off without taking the fan shroud and assembly out? If so I want to know how! I need to replace the pulley bearing on mine but given that I thought I had to remove everything to get to it I was waiting until I had the time, funds, and parts necessary to do a major overhaul of my cooling system.

Well...I just explained how I did it.

I think if you want to replace the bearing you need to fit a puller in there - which probably won't fit without taking the fan out. But nothing is keeping you from trying!

I removed the clutch face by hand - no pulling. It was a little worn, but not gouged or grooved. It was getting dark, so I didn't get a clear look at the friction material. It was so easy that I figured I'd take it apart later if it didn't work.

 

[Sparky]

I meant how did you get to it in the first place? from below? I can't even reach down to the pulley from the top with the fan in the way I don't think.

I don't mean to sound stupid but I can be somewhat dense at times

 

[envisionelec]

I meant how did you get to it in the first place? from below? I can't even reach down to the pulley from the top with the fan in the way I don't think.

I don't mean to sound stupid but I can be somewhat dense at times

I'm an engineer, so I tend to be logically-driven. I reached from the top down. I'm 6' 3" and my wingspan is 6' so I often take my ability to stretch/reach for granted. There is a steel tube which blocks access from the bottom, so top-down was my only option without further disassembly.

 

[Sparky]

Ah OK. I'm 5' 11" and while I have a good reach that's a bit of a stretch for me to get down there and be able to get any leverage on anything. I knew about the tube because I looked from underneath, but I thought maybe I was just missing something. I'll just do it all at once like I originally planned then.

I'm an engineer also but more on the electrical side of things.

 

[envisionelec]

I'm an engineer also but more on the electrical side of things.

I'm a EE...it's also "more on the electrical side".

 

[Sparky]

Then I guess you're quicker than I am. Sometimes it takes me a while to figure out the best way EET here.