My 96 LT1 that I purchased about 2 years ago has never had the a/c work since I have had it.

I recently learned that it is probably low on freon and as a safety mechanism the a/c does not cycle to protect the a/c equipment.

What do I need to do at this point?

Does the a/c system need to be vacuumed?

Can I recharge the system with straight freon, no oils or seal fixes?

I am hoping to hear from an a/c guru or someone who works at an a/c shop, but any knowledge is better than where I stand now.

Never worked on a/c system so I do not want to f%&* it up.

It is a real nice car and I want to make sure everything works as it is suppose to. I may sell it in the near future, but I want to fully enjoy it and provide the new buyer with a great car. Besides I live in Humid Houston, TX so you know its gonna get hot sooner or later.

 

does the light for your AC flash when you turn it on? if so its probably low on freon or doesn't have any. you can get a freon gauge from any auto parts store and see if it has freon, while running the car hook the gauge up, if it is very low, or no pressure at all you need a charge, go buy some 134a turn the car on with the ac on running full blast and as you are charging it your compressor should kick on, if it doesn't kick on you have other issues.

 

I am under the impression that I need to disconnect the battery first, then jump the connector by the orifice tube, reconnect the battery, turn the car on, and only then will the a/c work in order to recharge it or get a pressure reading.

I am probably wrong, but I am just checking.

 

There could be several different issues causing your A/C problem. The first thing I check is an open low refrigerant pressure switch caused by low/no refrigerant in the system. With the ignition key OFF, I disconnect the R134a refrigerant low pressure cutout wiring connector from the switch (of course, leaving the switch in the refrigerant plumbing) and jump across the disconnected wiring harness connector terminals with a short piece of wire. This simulates refrigerant pressure in the system and will allow the refrigerant compressor to run if the problem is low/no R134a in the system. I start the engine and set the air conditioning control to ON. If the compressor clutch engages and the compressor runs, the system is low on R134a refrigerant and needs to be charged. I only run the compressor long enough to verify operation, as it can be damaged by extended operation without refrigerant in the system. I shut off the engine, remove the jumper wire and reconnect the low pressure cutout. As Daniel stated, R134a recharge kits can be purchased at most auto parts stores and most have comprehensive instructions. Of course, if your system is low on refrigerant, the leak should be found and repaired for a permanent fix.

 

Thanks, I will try that this week end.

Is it ok to do this without suctioning out the system first?

Hooking up the car's a/c system to a vacuum machine.

 

Yes, you can do this witout pulling a vacuum on the system. TYPICALLY the system is only dehydrated (all air and moisture removed) by connecting a vacuum pump and placing entire system into a vacuum, after the plumbing has been opened to the atmosphere for something such as removing and replacing the refrigerant compressor.

Let us know how it goes!

 

Definately don't run the compressor very long - I'd rather hook up a gauge to it as a way to tell if it's out of refrigerant - if there is pressure then jumper and check the compressor function for a second - the connection can be jumpered/removed with the engine running as that's a "normal function" that the system does when running.

FWIW - I've had a couple of old cars that tended to leak out a little refrigerant over time - I "fixed" a couple of my personal A/C systems by using the "refrigerant with stop leak" stuff - one was too far gone and my current '98 beater truck looses about a can a year through the compressor shaft seal - which a new compressor, dryer, orafice, etc. is around $300 for the parts, a can of refrigerant is $6... I'll keep throwing refrigerant at it until it leaks out quicker than a can a season... From what I can tell it works if it's an o-ring, hose crimp, or pinhole leak - it just won't seal compressor shaft seals or major leaks.

If you find it low then you might try the stop leak stuff - some hate it but I've had OK luck with it and if the system eventually fails I flush it out with the chemicals and change the oil charge in it anyhow so I'm not worried about any adverse side effects.

Just don't keep putting the stop leak stuff in over and over if it continues to leak - it's either going to work with the first treatment (2 cans if you're almost completely out of refrigerant) or it won't work and mechanical repair is going to be needed...

 

Does it leak oil out the front compressor shaft seal since that is where it leaks the freon?

Yeah, that stop leak won't fix a front compressor shaft seal leak since the shaft spins. That stuff works for things that don't move or spin.

My 89 started slinging some oil out the front compressor shaft seal after I pulled the frisbee and put a new belt on. So, I quit using the A/C for the time being. I'm thinking about pulling the A/C fuse so I can run my heat during winter without the clutch being engaged so it won't sling oil. Never did understand why the clutch engages for heat, but I'm guessing it wouldn't hurt anything for it not to.

 

The refrigerant carries the lubricating oil with it so wherever there is a leak there usually is an oily residue... If the compressor shaft is leaking slow it usually has a stain around the compressor and on the bottom side with dirt/dust adhered...

Your compressor won't engage if the low pressure cutoff switch is not tripped - it saves the compressor if the refrigerant leaks out. Of course if it's the front shaft seal you can try and replace it (factory air has all the parts) but I've never had good luck with that as a DIY repair... a reman compressor is what I've always put in it to fix that problem...

 

If you don't see an oily stain of a suspected leak anywhere but you still lose refrigerant, It's more than likely one of the schrader servicing ports.
Sometime in the 90's GM started using a new style on the Hi side, these are notorious for leaking. They take a special socket to remove(double square) and the system has to be evac'd to replace them.

 

The AC clutch engages on other cycles other than "cold mode" to keep oil on the shaft's carbon seal at regular intervals....this "preserves" the compressor seal's life by keeping at least some oil on it so that the next time the compressor engauges it isn't isn't totally "dry" for the first few seconds of engagement. People often wonder why their compressor seal fails even though never run their AC- it is because most of the seal damage can occur before the seal gets oil. It is a good idea to run the AC/heater/defroster at regular intervals to keep the shaft seal coated in oil.

 

Ok, thanks. Doesn't sound good for the guys who store theirs away for the winter. I'll keep it disconnected for the winter as it does leave a splatter under the hood. And connect it every so often to keep the seal from drying out and getting worse than it already is.

 

Once they leak it doesn't matter and eventually it'll spit out enough oil so that nothing is lubricating the compressor. Nor would I run a compressor with a leaking shaft seal because it will groove the shaft. You can service the seal for 50 Bucks assuming the shaft isn't shot. You won't know until you take it apart. There are better double lip seals too which can sit for years and not fall apart. You do need to rebuild (ie, fix the compressor and replace the Accumulator) because you don't really know how much oil is in it and it takes the full 8 ozs to keep it all together.

The '89 doesn't engage the compressor for Heat - only Auto, Defrost and Bi-level.

Get the oil off the hood so it doesn't leech through and eat up the paint.

 

I usually run the heat on the "Bi-level" as it blows better. I would set it to "Auto" but for some reason with heat in that setting, it just does defrost. I'll use the heat on the ECON or HTR setting for winter so the compressor doesn't engage.

I'm just not gonna use the A/C. Don't want to spend $600+ on it. Might could get by just replacing the seal, but who knows. Plus it still has R12, so it would be even more costly to switch over to R134 to replace all the seals, flush it, orifice, etc.

 

I'd take it to a shop. LT series A/C compressors are unique, low production items; a compressor plus clutch alone can cost nearly a $1,000. It is not like experimenting on the old Chevy sedan with a can of freon in one hand and a beer in the other. Trust me on this one.

 

Well, they're not that unique. '88 through '96 use the Nippondenso 10PA20C Compressor. In '92, or for the LT motors, the Manifold is reversed and the hoses come off the front. Unfortunately, in spite of being used for 8 years, a new one from A/C Delco or your Dealer is going to run around $500 plus a clutch if you want to replace that too. You might save a few Bucks reusing your Manifold, but you'll need a new o-ring or gasket. Buy a shim kit if re-using the clutch. Earlier C4's used a Harrison R4 but the quality is in the Nippo and the brand is used in the high end stuff - Lexus, Mercedes, Porsche, etc - so that may explain the pricing. I'd stay away from Discount Auto Parts rebuilds. Their reputation is horrible and last "new" one I bought at Auto Zone was crap out of the box.