Bizarre ac behavior

[1998_K1500_Sub]

When you re-install the (new) compressor, first check to see if it sits flat (doesn't rock) on the four mounting pads. If it rocks, find a way to shim it or otherwise make it sit flat. Why? If it rocks and you tighten it down, it'll put a twist in the body that works to break the seal in the middle of compressor.

I've got a GM TSB around here somewhere that makes this claim, I didn't make it up myself

 

[someotherguy]

When you re-install the (new) compressor, first check to see if it sits flat (doesn't rock) on the four mounting pads. If it rocks, find a way to shim it or otherwise make it sit flat. Why? If it rocks and you tighten it down, it'll put a twist in the body that works to break the seal in the middle of compressor.

I've got a GM TSB around here somewhere that makes this claim, I didn't make it up myself

I've heard this one before and it makes sense, considering the design of the HT6 compressor case, its seal, and how it mounts. The TSB would be nice to have here as reference, if you can dig it up.

If it does rock, it would seem that putting the compressor on a known very flat surface to see if it is capable of mounting flat would be my first step, then adjust either the compressor or the mounting bracket if needed.

If it's the compressor I wouldn't be surprised as who knows what happens to them through their journey of removal, core process, reman, resale. Tossed around in bins of cores along the way, shipped several times, rebuilt.. imagine if simply the case halves aren't assembled with 100% precision then they could never mount perfectly flat, leading to premature failure.

If it's the bracket, plenty of care needs to be taken to be sure you get it sanded/ground down perfectly flat on all 4 points. You don't want to go crazy on it, tiny little bit at a time, checking your work frequently before continuing.

Richard

 

[Ranger550]

Stop where you're at. Take the compressor back to where you got it, explain everything up to this point and get your money back. Buy a better-quality compressor from a reputable brand. After that compressor ran with no pressure, I wouldn't trust it.

I second this advice!

 

[drdoom1337]

I've been issued a full refund from the online merchant t I bought it at. They didn't ask for the compressor back either as they couldn't issue me a replacement.

I will still do a full vacuum test on it as the clutch does engage now when I jump the low pressure switch. I guess I just didn't have enough r134 in the can to kick it on.

If it is in fact bad, I will order an ac delco or Delphi unless someone can recommend a better solution. I know the 4440 sanden used to be a standard but I only see knockoffs now.

 

[L31MaxExpress]

I've been issued a full refund from the online merchant t I bought it at. They didn't ask for the compressor back either as they couldn't issue me a replacement.

I will still do a full vacuum test on it as the clutch does engage now when I jump the low pressure switch. I guess I just didn't have enough r134 in the can to kick it on.

If it is in fact bad, I will order an ac delco or Delphi unless someone can recommend a better solution. I know the 4440 sanden used to be a standard but I only see knockoffs now.

I ordered my Sanden directly from Sanden in Wylie, TX. Be sure to order their oil if you go that way. The SP oil they specify is more difficult to find than the genuine compressor. I do not regret the Sanden at all. It is smooth, quiet and cools extremely well.

 

[1998_K1500_Sub]

I've heard this one before and it makes sense, considering the design of the HT6 compressor case, its seal, and how it mounts. The TSB would be nice to have here as reference, if you can dig it up.

If it does rock, it would seem that putting the compressor on a known very flat surface to see if it is capable of mounting flat would be my first step, then adjust either the compressor or the mounting bracket if needed.

Here's one reference relevant to the "trueness" / "flatness" of the compressor mounting bosses. The Sanden "SD Compressor Service Guide" (attached) on pg. 9, Section 6.5.2 Mounting Ear Deflection, speaks to the requirement.

I still swear that I've read similar requirements in a GM TSB(s), but I haven't found one yet in my archives.

 

[L31MaxExpress]

Here's one reference relevant to the "trueness" / "flatness" of the compressor mounting bosses. The Sanden "SD Compressor Service Guide" (attached) on pg. 9, Section 6.5.2 Mounting Ear Deflection, speaks to the requirement.

I still swear that I've read similar requirements in a GM TSB(s), but I haven't found one yet in my archives.

I swear I have seen one from GM as well.

I have resealed a couple of them. It is not twisting that causes them to leak. It is aluminum corrosion. You can polish out the corrosion, reseal them and the success rate is pretty decent, but I do not like the design compared to the Valeo or Sanden replacements I have used. The Valeo compressor kit cost me $189 in 2005 when I installed it and it worked flawlessly for years. The last 2 summers it ran on the old 350, it started knocking. It never got worse and never stopped functioning. When I pulled the system down the screens were clean on the orifice tube. I rebuilt the ac system while I had the system torn open anyway.