I'm putting this out there in hopes that on the off chance that any other poor soul who may be suffering from my disease (head up the rear end) will find this and have the same "aha!" moment as me, but with less time, money and energy as I did.

Basically, I purchased my 1994 Blazer back in April/May knowing that the AC was not functioning, and was told that it was because there was no condenser. I knew this could not be all of the problem, but it was a good deal and I wanted to learn AC work anyway. (HA!)

I won't go into all the details of my AC debacle, including the torn labrum, trip to the orthopedic surgeon, physical therapy, etc..........because 95% of what you need to know about AC self diagnoses is available via web searches and frankly the story is embarrassing. LOL

My ultimate frustration came from the fact that after having installed everything brand new with the exception of the compressor (which was working fine) and evacuating and properly charging the system with gauges, etc. I could not not get the darn thing to work. The problem was once I had enough refrigerant in the system to activate the low pressure switching and kick on the compressor, then the compressor pressure would get too high, thus activating the high pressure switch and killing the compressor. During this on and off cycle of the compressor I could feel the line going to the evaporator coil getting cold, so I knew in theory everything else was working.

I did search after search and tried everything short of a rain dance and voodooo. I was at my wits end. I even pulled the orifice tube (my thought was it was causing the pressure) and ran it like this for 2 days. What I got was "cool" air, but not cold air. In the mornings it was fine, but in the heat of the afternoon it would just seem cool enough to keep you from sweating. Not what I wanted after the $$$ I had spent. So I installed the gauges again and noted that pressure on the high side was low and the low side was high. They were not equal, but much much closer than they should have been. So off to the part store I go for $45 more of r134 and a new orifice tube. Same thing...too much pressure on the high end...cycling on and off of the compressor.....at this point I wanted to curl up on the garage in the fetal position and cry. My wife, who knows better, even suggest I pay someone to evacuate and charge the system.....um nooo...I will not be defeated.

So I go to bed that night feeling defeated a little less a man. Haha. I wake the next day and as I'm about to leave for work, I decide to take one more look at things and that's when it hit me.......the line going from the compressor to the condenser and the condenser to the evaporator were the same size fitting. I even bothered to check before I left (evacuating the $45 worth of r134). Off to work I go feeling better, perhaps I reversed the lines??? So I did a web search for "chevy condenser" and FINALLY found a picture that confirmed my fears. I had installed the condenser upside down which had lead to me installing the refrigerant lines incorrectly. Since the truck had no condenser when I bought it, and the lines had been cut by whoever removed the condenser, I had no idea. And apparently not enough sense to check first. I seem to recall doing something but this AC business started 2 months ago and was interrupted by 4 weeks of "no wrenching" when I tore the shoulder.

At any rate....I went home that afternoon, flipped the condenser, reversed the lines so that the evaporator line was attached to the orifice tube side of the condenser and VOILA.....no high pressure on the compressor and ice cold air in the truck.

When I had the high pressure issue I read post after post after blog after blog after how to article...etc. on everything imaginable that could go wrong with the AC system. There is just nothing out there that explains this problem at all. Everything points to the high pressure switch or the orifice tube being blocked. Neither was my problem. My problem was that I was trying to force the refrigerant straight from the compressor into the orifice tube, because I had the lines hooked up incorrectly, because the condenser was upside down.

Yes, I'm an idiot for not checking how to install the condenser when I bought the new one, but maybe me being an idiot and this post will save some poor soul some heartache later down the road.

 

Thanks 4 your post. I'd appreciate if you tell me which end must go to.... I have the same issue. I removed everything and I didn't pay attention whhere the lines were connected to.... On the condenser I see 2 fittings one upper and one down which goes to the evap and which to the compressor?

Thanks

 

Gotenks2......Sorry, going off memory here, but there should be two fittings, as you stated, one that is at a 45 degree angle to the condenser with a straighter section, and one that is sort of "Z" shaped, but the the "Z" straightened out. The one with the longer straight section will be where the orifice tube is located. If the condenser is still attached to the front of the vehicle, you probably can't see the orifice tube, but if it's out, you should be able to look down that straight section of tubing going into the condenser and see the orifice tube. Another way to think of it is that the orifice tube is about 3-4 inches long and it needs that much of a straight section plus an inch or so recess to fit it inside the tubing behind the fitting, so it'll be the fitting that has a 4-5 inch straight section immediately following it. This side goes to the evaporator. The "Z" shaped section will attach to your compressor line.

I hope this helps, please if not, let me know and I'll see if I can get some pics to help.

 

Thanks for your answer. Your condenser is different than mine. In mine both fitings are looking forward and both are straight but I saw a pic of the one you say and I think I connect them backwards too.

I installed everything new but my new compressor is making a horrible whining noise, and I think I'm getting too much pressure (50 psi at low pressure line and 250 ~ 300 psi at high line) with an ambient temperature of 85°). The air is blowing warm... when I accelerate it cools down a little bit but the compressor shuts off... (when the engine is at more than 1200 RPM the compressor shuts off every 3 or 4 secs)

I installed compressor, accumulator, orifice tube (I got the variable tube) all brand new. I flushed everything and I applied vacuum for 60 mins before charging R134a. My old compressor was colling fine but it had a leak on the back, that's why I replaced it.

Another thing. The new compressor came with 8 oz of PAG46 oil. I drained it and put 3 oz to the compressor, 2 to the accumulator, 2 to the evaporator and 1 to the condenser., but the original one used PAG150. I don't know if that could be the problem. THe other things changed was the orifice tube. THe original was the normal fixed tube and I put the variable since it's more recommended for severe climates but again I don't know if that's a big problem.....

Any ideas?

 

ohh I forgot to say that I have exactly the amount of R134a by weight. So it's not an overcharge of freon. 28 oz exactly and it's what the sticket on the hood says.