ehuron

AC system completely replaced (original GM, non reman parts). Will only get fairly cold on highway but hardly even cool in traffic. Compressor replaced twice and orifice twice. High side reads correct, but low side stays at about 60lbs indicating possible blockage. But, can't find one. I did see an orifice available for this car that was forty two dollars, expensive but needed?

Bob in Elliot Lake

I'm not an auto a/c guy, but I am a refrigeration mechanic (mostly grocery stores). I would expect a restriction in the system at the oriface to cause low suction pressure, not high, unless the restriction is between the port where you are measuring pressure and the compressor. Is there a filter/drier between the low side pressure port and the compressor? If so I would suspect that. When I get a chance later today, I'll look at a drawing of the a/c system for clues.

Bob in Elliot Lake

I tried to find a diagram, found a couple but not much detail about the components. If your compressor is actually running, and your measuring high low side pressure, there either has to be a restriction of some sort between the pressure port where you're reading the pressure and the compressor, or the compressor has failed. I did find one reference to the accumulator referring to it as an "accumulator / drier", as I said, not unusual for a drier to plug up, but it looks from the diagrams I did find that the accumulator drier is up stream of the pressure port so that shouldn't be the problem. A good a/c tech should be able to identify a restriction quite easily if there is one, or a bad compressor. Sorry I wasn't more help, but without seeing it hands on so to speak, it's difficult

Bob in Elliot Lake

Are you doing this work yourself? If so did you pull an adequate vacuum on the system to ensure there's no moisture or non condensables (air) in the system before adding refrigerant?

Pounder

maybe this will help ???

ehuron

we change the orifice yesterday. no change, but will have to check on the filter/dryer where you mentioned. The dryer is new but doesn't mean it isn't faulty, even though it is oem gm.

ehuron

NOT myself. I have an auto ac person doing the checking. He also did the installation of the entire system. I was and am there for all the work. Yes, he does have all the equipment. With every check he has pulled the vacuum down as far as could be done. We've added the right amount of freon, gone just a little more, and just a little less each time. Still can't get the low side below 60-61 lbs which keeps the vent (vents) temp no less than 64-65 degrees. Should be about 44-46 degrees. We have changed the orifice but not the dryer, which is new.

ehuron

Thanks, but my ac guy has all of this on his diagnostics discs. We even put in a new radiator with double the capacity. Guess we might have to change the new dryer and the evaperator also. Other than that, we are baffled. Again, all parts are gm and not remans, though, that doesn't mean one or more aren't faulty.

Bob in Elliot Lake

I would still look between the pressure measuring port and the compressor. A restriction in the evaporator should cause low pressure, not high. When you figure it out, let us know, I'm curious

ehuron

I guess we're going to have to start changing other new parts, like the evaporator. The compressor has been changed twice. Man, I was hoping this had happened to other vette owners who had replaced their entire ac system, and had an answer. When we get it working, I'll let you know.

Remow2112

I had a similar problem. Freeze you out on the highway and was mediocre at best in town. In my case the evaporator fins were mostly blocked by years of junk getting stuck in them.

In my case I was changing the radiator so I ordered a new evaporator and it now works much better. From your symptoms it almost has to be the evaporator since your gauge is off on the low side.


HTH,
Dan...

ps. I have a 98 and rebuilt my ac except for the evaporator. Kicked myself when I discovered the problem. Lived with it until radiator started leaking and did them both.

ehuron

I believe you are exactly correct. I was under the assumption, when I had everything replaced, that they replaced the evaporator also. I found out today that they only flushed it. I also found that on my (1998 C5) that flushing it is usually fine, but you must back flush it also. Because of it's location it is set at an angle so that junk and oil accumulates at bottom. Back flushing will take care of that (I hope) but the final flush has to be from the proper direction. We are going to suck it dry tomorrow and do the flushing. With a little luck that will solve the problem. But I am now 99.9% sure it's at the evaporator. Thanks for making me sure that that is the origin of the issue.

redzg

I think you guys must be talking about the condenser? The evaporator is inside the dash, no?

ehuron

Yes. We tracked the problem back to the evaporator. And yes, it's in dash, and yes, it's going to be expensive. Not only that, I broke the adjustment rod on driver side headlight assembly. Unless I can find something, that's going to be expensive. And yes, I'm still going to keep the car no matter.

redzg

"I'm still going to keep the car no matter"
Could not be in greater agreement!

domenic tallarita

Neal, cheyymans 77. I am going to start a thread and use your belt on pulley theory. Great and makes sense. Compressor leakes are a C2 problem. One caused by exactly what you pointed out about the pulley being off set by a over tightened belt. Off set causes 2 part seal to move on face as you said.
Thread will be NCRS.


Dom

USAZR1

This is a C5 forum, not C2 or C3.

Vetteman Jack

Closed and moved to C5 Tech.